Tiêu chuẩn Việt Nam TCVN13521:2022 national Standards TCVN 13521:2022 for Residential and public buildings - Indoor air quality parameters

NATIONAL STANDARDS

TCVN 13521:2022

RESIDENTIAL AND PUBLIC BUILDINGS - INDOOR AIR QUALITY PARAMETERS

Foreword

The TCVN 13521:2022 is developed by the Vietnam Association of Civil Engineering Environment, proposed by the Ministry of Construction, appraised by the Commission for the Standards, Metrology and Quality of Vietnam, and publicized by the Ministry of Science and Technology.

RESIDENTIAL AND PUBLIC BUILDINGS - INDOOR AIR QUALITY PARAMETERS

1 Scope

No.

Parameters

Acceptable limit

Unit

Measurement/analysis methods

PM2.5 dust

µg/m³

ISO 16000-37:2019

PM10 dust

100

µg/m³

AS/NZS 3580.9.7:2009

AS/NZS 3580.9.6:2003

Lead (Pb)

1,5

µg/m³

TCVN 6152:1996

Carbon dioxide (CO₂)

1000

Ppm

TCVN 10736-26:2017

Carbon monoxide (CO)

mg/m³

ppm

TCVN 7725:2007

Formaldehyde (HCHO)

100

0,08

µg/m³

ppm

TCVN 10736-2:2015

TCVN 10736-3:2015

TCVN 10736-4:2015

Total volatile organic compound (TVOC)^a

500

µg/m³

TCVN 10736-5:2015

TCVN 10736-6:2016

Nitrogen dioxide (NO₂)

100

µg/m³

TCVN 10736-15:2017

Sulfure dioxide (SO₂)

100

µg/m³

TCVN 5971:1995

TCVN 7726:2007

Ozone (O₃)

100

pg/m³

TCVN 6157:1996

Total bacteria in the air

- Public building

- Residential building

1000

1500

cfu/m³

NIOSH Manual of Analytical Methods 0800

Total moulds in the air

- Public building

- Residential building

500

700

cfu/m³

TCVN 10736-16:2017

TCVN 10736-17:2017

TCVN 10736-18:2017

TCVN 10736-19:2017

TCVN 10736-20:2017

Radon

- New building

- Existing building

< 100

< 200

Bq/m³

TCVN 10759-4:2016

TCVN 10759-5:2016

TCVN 10759-6:2016

NOTE: Limit value of air quality parameters (other than radon) under Schedule 1 that is applicable to public buildings shall be mean value for 8 hours working in a day; that is applicable to residential buildings shall be mean value for 24 hours in a day. The radon limit shall be the mean value of 3 consecutive months.

Number of storey occupied in a building

Percentage of storeys randomly selected for sampling (%)

Less than 5

80 % of the storeys^a

From 5 to 10

70 % of the storeys^a

From 11 to 20

60 % of the storeys^a

From 21 to 30

12 storeys or 50 % of the storeys^a, whichever is higher

From 31 to 40

15 storeys or 40 % of the storeys^a, whichever is higher

From 41 to 50

16 storeys or 35 % of the storeys^a, whichever is higher

Exceeding 50

18 storeys or 30 % of the storeys^a, whichever is higher

NOTE:

Specimens under Schedule 2 will ensure 90% of reliability if the specimens are collected from at least 1 storey among the 10% number of storeys with the highest indoor air quality parameters.

^a This value is rounded to the nearest integer.

Appendix A

(Reference)

Exposure control - Ventilation

A.1 Ventilation flow

For the purpose of designing HVAC for comfort, minimum outdoor air flow required for any occupied building space shall be calculated in accordance with the TCVN 5687:2010. Outdoor air flow for occupied building space under TCVN 5687:2010 has already taken into account occupant load in fire prevention principles of buildings, odor dilution requirements for odor of humans and human activities, odor of pollutants from construction materials, furniture, and interiors.

A.2 Outdoor air flow required according to hygienic requirements

Outdoor air flow delivered indoor in accordance with environmental hygiene requirements for air-conditioned rooms shall be calculated so as to dilute hazardous substances and odor exuding from human body, furniture, and interior. In case of insufficient conditions for calculation, outdoor air flow delivered indoor may be determined per occupant or floor area under Schedule A.1 below.

Schedule A.1 - Standard outdoor air flow delivered to air-conditioned rooms in comfort mode in accordance with environmental hygiene requirements

No.

Type of room

Area

m²/person

Required outdoor air flow

Note

m³/h.ng

m³/h.m²

Hotel, motel

Bedroom

Regardless of room area

Living room

Corridor

Meeting, conference room

Foyer

Office

12 - 14

Lobby

1,5

Dormitory

Bathroom

Infrequent use

Dry-cleaner

Restaurant and diner

Dining room

1,4

Café, snack room

Bar and cocktail counter

Additional smoke extraction system required

Kitchen (cooking)

Odor control system required. Total outdoor air flow delivered must allow minimum extraction rate of 27 m³/h.m²

Theater, cinema

Auditorium

0,7

Special ventilation required to remove negative effect of stage set-up, pyrotechnics, fog, etc.

Corridor

0,7

Studio

1,5

Ticket booth

1,6

Training facility, school

Classroom

Laboratory

3,3

Additional information under dossiers on laboratory

Conference room, training room

3,3

Library

Assembly room

0,7

Music theory room, singing room

Corridor

Storage unit

Hospital, infirmary, convalescent home

Patient room

Examination room

Operating room

Post-mortem examination room

Air from this room must not be delivered to other rooms

Physical therapy room

Dining room

Security room

2,5

Sports, athletic competition, and recreational building

Bleachers

0,7

Competition room

1,4

Indoor ice-skating rink

Indoor pool with bleachers

Greater air amount might be required to control humidity

Ballroom

Bowling alley

1,4

Public areas

Corridor and household article storage unit

Shop house row

Store

Lounge

1,5

Smoking room

1,5

Smoke must be extracted and not circulated

Special store type

Barbershop

Beauty supply store

Clothing, wood article store

Flower shop

Supermarket

Coach station, railway station

Waiting room

Terminal (indoor)

Administrative and office building

Office

8 - 10

Seminar room, conference room, boardroom

Waiting room

Residential building

Bedroom

8-10

Living room

8-10

NOTE: The area in m²/person means the actual area required for a person in a room

[Source: Appendix F of TCVN 5687:2010 Ventilation-Air conditioning - Design specifications].

A.3 Ventilation characteristics

Quantity of air exchange must be of significant importance for indoor air quality. Proper indoor ventilation is paramount for health and comfort of occupants and protection of property. In respect of modern buildings such as high-rise apartment buildings and office buildings with closed windows, ventilation might be insufficient which accelerates concentration of indoor pollutants. As such, mechanical ventilation of occupants or HVAC system is necessary. However, excessive ventilation may cause loss of comfort and increase energy consumption.

Construction regulations prescribe ventilation requirements for control of humidity and other contaminants. Measurements relating to ventilation conditions shall permit verification of whether these requirements are met in practice. Knowledge pertaining to ventilation conditions is paramount in analyzing causes of unsatisfactory indoor air quality. As such, sampling and analysis of indoor contaminants should best be accompanied by wind measurements through which emission rate of contamination sources can be determined.

A.3.1 Use method

Methods relating to the use of tracer gas technique for determining air exchange rate [TCVN 10736-8 (ISO 16000-8)] and air change effectiveness.

A.3.1.1 Air exchange rate

Air exchange rates (as an indoor ventilation parameter) can be defined by determining the local mean ages of air (and its inversely proportionate effective local air exchange rate) in the building. Local mean ages of air in a zone of a building indicate the average age of air containing pollutants in a zone of the building and are closely related to air exchange time of that zone.

Concentration of a pollutant from indoor sources of continuous emission increases proportionately with ages of air indoor. As ages of air in a space decrease, concentration of pollutants also decrease. See TCVN 10736-8 (ISO 16000-8) for a detailed description of relevant procedures and measures.

A.3.1.2 Air change effectiveness

Ages of air determined by tracer gas technique can be used for calculating air change effectiveness in air-conditioned or mechanically ventilated buildings. This value illustrates level of ventilation relative to level of ventilation achievable in an ideal piston volume. Air change effectiveness is defined by comparison between age of air in occupied space of the building and age of air in perfectly ventilated condition. In respect of complete mixing system, air change effectiveness equals 1. Methods for measuring air change effectiveness in air-conditioned or mechanically ventilated buildings can be consulted under ANSI/ASHRAE 129-1997 (RA 2002).

Appendix B

(Reference)

HVAC system maintenance

B.1 Inspection of HVAC system

HVAC system must be visually inspected for cleanliness. Recommended inspection frequency for primary parts of HVAC system is specified under Schedule B.1 below. The frequency of inspection and cleaning can be increased depending on the environment, mechanical ventilation conditions, and human factors. Schedules under Appendix B are also used to select methods and necessary input data and provide reference to other documents.

Schedule B.1 - Recommended interval of HVAC system inspections

Parts of HVAC system

Inspection interval

Heat exchanger

6 months

Air supply ducts

12 months

Return air ducts

12 months

Hygiene inspection shall be conducted in a way that does not disturb settled dust, exacerbate microorganism or other debris to an excessive manner that negatively affects indoor environment.

AHU, other parts of HVAC, and air ducts must undergo hygiene inspection. Minimum percentages of systems and parts that must be inspected in different scenario are specified under Schedule B.2.

Schedule B.2 - Parts recommended for inspection

Scenario

System to be inspected

Part to be inspected

Periodic inspection

10% of similar equipment system

• Outdoor air intake

• AHU

• Primary duct

• 10 % of branching duct

Defect found during periodic inspection

100% of similar equipment system

• Outdoor air intake

• AHU

• Primary duct

• 10 % of branching duct

In response to complaint

100% system(s) serving affected area

• Outdoor air intake

• AHU

• Primary duct

Branching duct

B.1.1 Internal surface inspection for HVAC system

Two internal surface tests can be conducted to indicate whether the system is capable of producing pollutants to indoor air:

a) Thickness of settled dust;

b) Vacuum test.

All recommended tests shall be repeated within an interval of at most 12 months. Proposed points for testing and minimum number of test points are specified under Schedule B.3.

Schedule B.3 - Proposed point for tests

Total air duct length of each system

Test points

Minimum test points

The first 300 m

1 test point per 50 m

3 points for the whole system

> 300 m

1 test point per 100 m

Mean values shall be calculated for all test points of each HVAC system. Result of the calculation shall be used for determining whether system cleaning is necessary.

B.1.2 Situations that warrant HVAC system cleaning

HVAC system must be cleaned where cleanliness test results of the system indicates that the system has been contaminated or that efficiency of the system is reduced due to pollution build-up. Conditions of HVAC system that warrant cleaning are specified under Schedule B.4.

Schedule B.4 - Conditions of HVAC system that warrant cleaning

Conditions of HVAC system

Definitions

Pollution of HVAC system

• In case of significant build-up of substances that are not supposed to be present in HVAC system (e.g. dust, dirt, debris) and microorganism growth which is visible.

• Where HVAC system produces visible dust particles to occupied space or produces more dust particles in indoor spaces.

Reduced efficiency

Where parts of HVAC system are affected, congested, or covered with filth build-up which reduces system efficiency, reduces air flow, or causes other conditions that significantly impairs design goals of the HVAC system.

HVAC systems must also be cleaned if internal surface test results indicate a level of build-up higher than the recommended level. Build-up limit at which HVAC system cleaning is recommended is specified under Schedule B.5.

Schedule B.5 Build-up limit at which HVAC system cleaning is recommended

Type of system

Surface dust build-up limit

Test method

Extraction

6 g/m²

Vacuum test

180 µm

Build-up thickness test

Circulation

1 g/m²

Vacuum test

60 µm

Build-up thickness test

Supply

1 g/m²

Vacuum test

60 µm

Build-up thickness test

Appendix C

(Reference)

Indoor air quality, work productivity, and health

C.1 General definitions

Despite existing scientific publications pertaining to indoor air quality, work productivity, and health, they have not been included in existing standards or laws. Connection between exposure to indoor environment and work productivity is still being extensively studied even when evidence regarding the effects of certain exposure on work productivity has been recorded. This Appendix provides a summary of science articles published regarding this topic and reaches a general analysis for buildings of reference ^[60].

During information interpretation, the following provisions must be taken into account:

a) Buildings of reference are located in different climate zones; very few buildings are located in tropical climate;

b) Specific effects of different conditions of indoor air quality (e.g. ventilation and temperature) on individuals accustomed to the tropical climate have not been analyzed from raw data.

C.2 Summarized analysis of buildings of reference

Indoor environment quality that does not meet acceptable level is related to the increase in symptoms of SBS, respiratory diseases, sick leaves, and reduction in work productivity. Calculations indicate that poor indoor environment quality may lead to higher energy, air-conditioning, and ventilation costs and that solutions for improving indoor environment quality will yield a higher effectiveness if costs for health or work productivity improvement are also taken into account.

Indoor environment quality is broader than indoor air quality as it also includes air quality, microclimate, light, acoustics, etc.

Initial models for quantifying benefits to health and work productivity as a result of improved indoor environment shall be presented on the basis of published analysis of previous buildings. Construction experts may choose building design and operation in a manner that takes into account effect on health and work productivity. These include quantified relationship between ventilation rate and short sick leave, ventilation rate and work productivity, perceptible air quality and work productivity, temperature and SBS. These details indicate a correlation between SBS and work productivity.

C.2.1 Ventilation rate and short sick leave

Ventilation helps reducing concentration contaminants in indoor air. Insufficient ventilation accelerates the rate of infectious respiratory diseases ^{[58],[43],[66]}.

C.2.2 Ventilation rate and work productivity

Ventilation affects work productivity indirectly and directly via its effect on short sick leave as a result of infectious diseases. This has been proven by data of 5 studies at appropriate workspace (working speed at telephone center, which is the duration of each call used as a measurement for work productivity) that has been adjusted, standardized, and weighted ^{[46],[45],[63],[64],[68]}; 2 studies in controlled laboratory environment (involving speed and/or accuracy of simulation of office work productivity) ^[42],[66]; and 1 study conducted at education institutions (utilizing the Swedish Performance Evaluation System for reaction time)^[53]. Tendency towards productivity increase where ventilation rate is increased to approximately 16 L/s-person at 90% reliability and to approximately 14 L/s-person at 95% reliability.

C.2.3 Perceptible air quality and work productivity

Evaluation of perception is an integrated measurement of air quality perceptible to human senses (olfactory nerves and facial nerves). The level of olfactory perception can be evaluated by trained or untrained test groups. Test groups are preferably untrained in which members shall evaluate whether air quality is acceptable or unacceptable throughout 8 hours of working in a day. Percentage of group members deeming air quality as unacceptable (unsatisfactory air quality) shall be used as air quality perception index. This data is apparently more sensitive than air quality evaluation via the use of frame of reference.

Laboratory studies ^{[65],[66],[67],[48],[42]} suggest that work productivity (where simulated office tasks include document drafting, complementary tasks, logical thinking) decreases proportionately with percentage of group members dissatisfied with air quality. However, it is unclear whether a lower air quality perception index is related to work productivity or whether a parameter of other factors in the building is in a causality with work productivity. Air quality perception index is affected by a number of factors. This index largely depends on contamination sources and ventilation flow as well as temperature and humidity.

C.2.4 Temperature and work productivity

Evaluation of 26 studies containing data from various administrative divisions suggest a relationship between indoor air temperature and work productivity ^[39].

C.3 Work productivity and SBS

C.3.1 Unacceptable indoor air quality and SBS

Studies have suggested that SBS is related to building characteristics and indoor environment. Risk factors identified for SBS include air conditioners ^[59], lower ventilation index and higher CO₂ concentration ^[58],[66], higher ambient temperature ^[49],[50], higher concentration of VOC ^{[61],[40],[41]}, dust and vapour excess in HVAC system ^[51], and humidity-related issues in buildings ^[57].

The followings have been discovered via reports of studies pertaining to popularity or severity of SBS and work productivity measurement.

a) During field study, objective evaluation of work productivity is negatively affected by SBS in office environment ^{[54],[55],[63],[64]} and in academic environment ^[52],[53];

b) During laboratory study reports, objective evaluation of office work productivity is negatively affected by SBS ^{[42],[48],[56],[65],[66]}.

The 2 studies that use objective productivity data indicate a relationship between productivity and SBS. Niemela and associates ^[55] propose that, based on data from a telephone center, an average reduction of 7,4 % points in weekly occurrence of central nervous system symptoms correlates to a 1,1% increase in work productivity decrease. Tham and Willem [64] reports a linear correlation between intensity of average score of nervous disorders and average conversation duration at a telephone center. Conversation duration that is improved (shortened) by 5% over 10 points will affect intensity of symptoms. Intensity of symptoms is measured by visual analog scale (VAS) from 0 to 100.

C.3.2 Temperature and SBS

Studies have reported correlation between a more humid temperature and a higher rate of occurrence or severity of SBS symptoms. 3 studies reporting severity of SBS symptoms have been conducted on-site in buildings without reported issues ^{[50],[63],[62]} and 2 studies have been conducted in laboratories ^[44],[47].

C.4 Summary

Data above indicate the effect of indoor air quality and conditions of buildings related to health and productivity of employees working indoor. Quantitative estimation of level of ventilation, temperature, and perception evaluation relating to work results and health can be conducted. Existing data indicate a relationship between SBS symptoms and work productivity reduction. Reliable analysis functions related to correlation of SBS symptoms and work productivity or sick leave will be valuable due to great number of existing data related to building design and operation and rate of occurrence of SBS symptoms.

Appendix D

(Reference)

Guidelines on attaining acceptable indoor air quality

D.1 Design

Indoor air quality is a result of design solutions achieving relevant factors which include more than just ventilation speed, ventilation characteristics, and air-conditioning. During building design and construction phase, relevant factors under D.1.1 through D.1.4 must be taken into account. Building design and construction consist of architectural design, insulation design for enclosing structures, sunlight blocking for windows, HVAC system. Design solutions shall be so determined that acceptable air quality is provided throughout normal building operation.

D.1.1 Location of building

D.1.1.1 Environment of building location

Environment of building location greatly affects indoor quality of the building. Careful consideration must be taken to minimize negative effect of nearby environment.

D.1.1.2 Outdoor air quality

Quality of outdoor air introduced to buildings must conform to regulations on ambient air quality. Where this is not feasible, consideration shall be taken for outdoor air treatment before introducing outdoor air indoor. Outdoor air purifiers of HVAC system must be able to meet parameters of outdoor air supplied to indoor spaces under Schedule 1.

Where concentration of ozone in outdoor air increases, consideration shall be taken for adoption of filtration techniques in order to reduce concentration of ozone in indoor air.

Location of outdoor air inlets must be determined reasonably, not in areas with wind curls, areas with possible pollution in order to maximize indoor air quality.

D.1.2 Indoor air contamination source and contaminant control

Pollution of heat, dust, toxic chemicals, microorganisms and moulds in indoor air is caused by indoor sources of pollution such as: indoor activities, construction materials, interiors, furniture, paints, adhesives, carpets, domestic animals, and outdoor pollution sources infiltrating enclosing structures. See Appendix E for control of indoor air contamination sources and contaminants. See Appendix F for control of contamination caused by construction materials and interiors. See Appendix H for control of indoor bacteria and moulds.

D.1.3 Ventilation characteristics

Outdoor air flow supplied to air-conditioned rooms in accordance with hygiene requirements shall be calculated in details so as to adequately dilute toxic substances and odor of human body, construction materials of interiors, and furniture. In case of insufficient calculation conditions, outdoor air flow supplied to rooms may conform to air flow per person or per m² of floor area in Appendix A. In addition to ensuring air exchange rate (or ventilation flow), requirements pertaining to distribution of fresh air and circulated air for acceptable indoor air quality must be met in occupied spaces depending on occupants’ need, adequate fresh air must be provided depending on occupants’ worshipping needs. Where ventilation efficiency must be determined, information pertaining to ventilation characteristics (such as air exchange rate and efficiency) shall be determined in accordance with Appendix A.

D.1.4 Nature and occupancy of buildings

D.1.4.1 Flexibility

Design of buildings and equipment system shall remain flexible to accommodate small changes in building use. Effects on indoor air quality should be assessed on a periodic basis.

D.1.4.2 Type of construction materials

Interior construction materials directly affect indoor air quality. Caution must be taken in selection of interior construction materials (see Appendix F).

D.1.4.3 Building cleaning

Adequate hygiene conditions must be constantly maintained in buildings as poorly maintained interior and furniture may negatively affect indoor air quality. Removal of contaminants via frequent and reasonable building cleaning may improve indoor air quality.

D.1.4.4 Airtightness and pressure difference

Design of enclosing structures must minimize infiltration of pollutants via enclosing structures from outside. Pressure differences between zones of buildings must be controlled so as to prevent unwanted spread of pollutants between zones.

D.1.4.5 Air cleaning

For the purpose of achieving acceptable indoor air quality, air cleaning must always be considered a vital part of a good HVAC system.

D.1.4.5.1 Air filters providing circulated air and mixed air

Two stages of air filtration include:

a) Pre-stage filters: Primary air filters of at least medium capacity shall be installed to protect secondary air filters of HVAC system.

b) Main-stage filters: Secondary air filters of a higher capacity shall be installed to protect building occupants from PM2.5 dust. Where outdoor air is delivered directly to occupied spaces (e.g. pre-cool outdoor air system), a combination of pre-stage filters and main-stage filters shall be adopted.

D.1.4.5.2 Monitoring pressure changes

Devices monitoring pressure changes may be outfitted with AHU to monitor conditions of air filters and accurately determine if replacement is required.

D.1.4.5.3 Other air cleaning techniques

Other air cleaning techniques for improving indoor air quality may be considered when appropriate. Potential benefits should be taken into consideration and weighted against potential safety and health risks.

D.1.4.6 Building occupancy

Occupancies of buildings must be taken into serious consideration as activities in the buildings will directly affect level of pollution of indoor air. For example, indoor air quality in office buildings is affected by exhaust of office interior, furniture, office supplies, and stationery such as photocopy machines and printers. Similarly, indoor air quality of food establishments is usually affected by humidity, smoke, odor caused by cooking, and smoking odor infiltrating from smoking rooms to other rooms.

D.1.4.7 Occupant number

Number of occupants in a space (occupancy density) must be taken into consideration for the purpose of designing HVAC system. Changes to number of building occupants must be taken into full consideration for the purpose of determining ventilation flow and the ability to replace air on a daily basis in each zone of the buildings.

D.1.4.8 Consideration for operation and maintenance of HVAC system

For the purpose of designing HVAC system, consideration must be taken in respect of operation and maintenance of HVAC system (see TCVN 5687:2010). Adequate and safe means for accessing parts of HVAC system that require regular maintenance must be provided.

D.1.5 Smoking areas and non-smoking areas

D.1.5.1 Separation

Smoking shall be prohibited in residential spaces, work spaces, study spaces, and public spaces. Smoking areas shall be physically separated from non-smoking areas by walls, partitions, and airtight doors.

D.1.5.2 Sign

Visible signs shall be installed in areas where tobacco smoke presents or may present. Signs should be located outside of each smoking area at visible location and at each entrance to said smoking area.

D.1.5.3 Pressure

Air pressure in smoking areas shall be lower than that of other areas.

D.1.5.4 Ventilation rate

Smoking areas must benefit from increased ventilation and/or air relative to equivalent non-smoking areas. Minimum ventilation flow of smoking areas can be mandated.

D.1.5.5 Air transfer

Air extracted from smoking areas must not be delivered or transferred to non-smoking areas whether by natural ventilation or mechanical ventilation.

D.1.5.6 Exhaust

Exhaust from smoking areas must be extracted outside in a manner that it cannot enter any non-smoking area.

D.2 Construction phase

D.2.1 During construction phase

During construction phase, the following measures must be taken to minimize potential pollution of indoor air environment.

a) Interior construction materials (such as carpets, furniture, soundproofing, etc.) and parts of HVAC system must be preserved and adequately protected from contamination during construction;

b) Plastering, welding, woodworking, painting, etc. activities must be carried out in a way that minimizes contaminants in indoor air. Measures must be taken to prevent dust contamination on the inside of ventilation ducts.

D.2.2 Before occupants reside or work at new buildings

a) Ventilation ducts must be cleaned (e.g. removing contaminants via mechanical cleaning) so as to remove all contaminants left in the ducts.

b) Indoor air must be cleaned so as to ensure that concentration of VOC and other contaminants conforms to Schedule 1.

c) Indoor surfaces must be clean and dust-free;

d) Amount of air entering a building must equal amount of air exiting the building.

D.3 Repair and renovation

For the purpose of repair, renovation, and upgrade of existing buildings:

a) Repaired, renovated spaces must be effectively isolated from other areas;

b) Materials and repair, renovation process must be determined so as to minimize pollution emission as best as possible;

c) Interior construction materials (e.g. carpets, soundproofing materials, ceilings, etc.) and parts of HVAC system shall be properly preserved and protected from contamination;

d) Fabrication and installation (such as welding, construction, woodworking, painting, etc.) should be carried out in a way that minimizes contaminants in indoor air;

e) Contaminants in ventilation ducts must be completely removed;

f) Measures must be taken to minimize the concentration of VOC and other contaminants in indoor air below the acceptable limit (Schedule 1);

g) Amount of air entering a building must equal amount of air exiting the building.

D.4 Operation and maintenance

Before a new building or an existing building that has been refurbished enters into operation, HVAC system therein must be tested so as to verify that its design and installation are capable of achieving acceptable indoor air quality. The entirety of HVAC system must not contain any construction debris and dust and must be cleaned prior to operation. All parts of HVAC system in buildings must be maintained in accordance with guidelines under Appendix B.

D.5 Indoor air quality control program

Specific indoor air quality control program must be developed in order to attain long-term goals (see Appendix G).

Appendix E

(Reference)

Contamination sources and contaminant control in indoor air

E.1 Selection of indoor contamination control solutions

E.1.1 Available solutions

There are many ways to reduce contamination in indoor air. Ventilation is commonly seen as a feasible solution as it can simultaneously reduce the concentration of all contaminants originating from indoor sources. However, ventilation is not always the best solutions. Whether a solution is selected instead of other solutions depends on several factors, including: characteristics of contaminants, origin of contaminants, effect of contamination on human, practicality, and relative economy (initial costs and operating costs).

The following solutions should be adopted to eliminate or minimize occupants’ exposure to contaminants in indoor air.

- Source control (see E.1.2):

a) Eliminate sources of contamination;

b) Replace with contamination sources that are less damaging or produces less odor;

c) Change source(s) of contamination to reduce the rate at which contaminants are emitted;

d) Manage contaminants at each position (see E.2);

e) Separate occupants from potential contamination sources;

f) Improve local ventilation, for example: via local gas extraction (in case of local contamination sources);

g) Employ air handling unit to reduce contaminants locally.

- Ventilation (see Appendix A):

a) Improvement of air exchange effectiveness, e.g. via adoption of ventilation system - mixing and displacement;

b) Adoption of appropriate air cleaning system;

c) Personal protection requirements.

These solutions are not mutually exclusive and may require combination with other solutions. Adequate ventilation will always be required regardless of approach.

E.1.2 Source control

E.1.2.1 Removal

Removal of a contamination source means to completely remove a contamination source as it is unnecessary in buildings. For example, relocate material storage units or technology procedures or prohibit certain activities (e.g. smoking tobacco, using cleaning liquid) when not needed. In some cases, eating and drinking may generate a significant source of pollution and may need to be limited at least temporarily if not spatially.

E.1.2.2 Replacement

Where pollution sources are required in buildings in any form, consideration shall be taken to employ materials or equipment that emits pollutants at a lower rate. Examples regarding possible solutions are provided below:

a) Materials of low pollution emission should be used indoor of buildings, as basic structure, furniture, technical system, and materials for building cleaning;

b) All new buildings shall be so designed to minimize unacceptable odor, increase separation distance to pollution sources as much as possible, and ensure economic feasibility;

c) Pollution sources in ventilation system or air-conditioning system must also be reduced, including by controlling intake of contaminated outdoor air via air intake;

d) Frequent cleaning and maintenance of indoor equipment and furniture are also important for the purpose of odor reduction.

E.1.2.3 Adjustment

Adjustments can be made to an extensive pollution source in order to reduce emission rate. For example, emission rate of materials changes depending on time, temperature, and humidity. Adjustment to materials in buildings (and ventilation of spaces at a higher flow) before occupation may reduce emission rate following occupation.

E.2 Local pollutant management

E.2.1 Separation

This provision relates to isolation of occupants from local pollution sources or contaminants. For example, in office buildings, it is possible to situate document storage units in areas separate from working areas of employees; separate areas for printers and photocopy machines can be prepared; and regulations on separation of smoking areas can be promulgated. Where such solutions are adopted, special attention must be paid to ventilation and airtightness in areas where contamination sources are located. Additional ventilation solutions are usually required in these areas.

E.2.2 Local extraction

Local extraction shall be close to contamination sources, such as: local extraction within vicinity of a photocopy machine or an area where chemical is used in order to reduce building ventilation demand. Double air curtains may improve air extraction efficiency.

E.2.3 Local air cleaning

Local air cleaning (filtering dust particles/contaminated air) can be adopted for the purpose of removing contaminants created in individual areas.

E.3 Dilution

E.3.1 General ventilation

Ventilation is the most popular approach to reduction of indoor contamination of buildings. Common strategy simply involves introducing outdoor air (commonly deemed fresh air) at calculated flow in order to dilute indoor contaminants.

This method is fairly simple: identifying contaminants present in rooms, identifying their effects on human health, and calculating permissible concentration of contamination. Indoor contamination sources, capacity, and permissible of concentration of contaminants shall be used in calculation of necessary outdoor air flow introduced indoor. However, dilution method may not be appropriate for some biological factors.

Where circulated air is used, general circulation system serving areas where similar industries are located must be taken into consideration unless circulated air is treated to meet acceptable quality.

E.3.2 Air cleaning

Air that has been cleaned prior to being introduced to an area helps reduce concentration of contaminants in the area. Circulation and ventilation flow may be cleaned individually and/or after being mixed. Where risks of exhaust air being drafted into ventilation flow, exhaust air cleaning also helps improve indoor air quality. Usually, this does not occur as air outlets and inlets are in separate locations so as to prevent mutual effect. However, exhaust air cleaning may still be required if outdoor environment surrounding outlets is negatively affected by exhaust air.

Air filters (with filter media) come in 2 types: filters for particle pollutants and filters for gaseous pollutants.

Different standards provide different recommendations pertaining to minimum efficiency of the filters but they are generally recommended for use as outdoor air filters in 2 levels: pre-stage filters and primary filters.

Appendix F

(Reference)

Control at source - Emission of construction materials

Interior construction materials may act as sources of indoor air contamination. In order to achieve indoor air quality goals pertaining to chemical exhaust, building designers should restrict the use of construction materials with high pollution emission. Construction materials with a lower emission must be selected as long as they satisfies all requirements under relevant law provisions, e.g. in terms of fire resistance characteristics, etc. This is extremely important where construction materials are used in great quantities within an area. Control of pollution emission from construction materials shall adhere to regulations under QCXDVN 05:2008 which prescribes emission of toxic substances from construction materials to ambient environment, protection of safety and health for individuals residing or working in buildings.

Due to limited choices of available construction materials and information, building design experts should utilize domestically available products and products of other countries or conduct emission tests on physical products where permitted.

In Europe, labeling programs have been implemented to control VOC emission from construction materials. Summaries of the aforementioned requirements for construction materials, flooring materials, and furniture are provided below (Schedule F.1).

Schedule F.1 - European labeling system for low-emission construction materials, flooring materials, and furniture

Labeling system

Classification requirements

The M1 label from Finland certifies finishing materials, fixtures, and furniture of office and residential buildings. https://cer.rts.fi/en/

Measurement of TVOC, CMR belonging to 1A and 1B, formaldehyde, ammonium, sensory-based emission acceptance must be conducted in environmental chambers. Test period of construction materials, fixtures, and furniture without covering is 28 ± 2 days. Test period of covered chairs is 3 days.

Limit values for construction materials and furniture: TVOC < 0,2 mg/m²h; VOC ≤ EU-LCI (µg/m³); Formaldehyde < 0,05 mg/m²h; Ammonium < 0,03 mg/m²h; CMR belonging to 1A or 1B < 0,001 mg/m³

GEV EMICODE from Germany for flooring materials, construction products, and surface finish products. https://www.emicode.eom/en/home

Material specimens are placed in stainless steel test chambers of 100 to 1000 liters in volume to conduct measurements, detect, and record concentration of VOC, carcinogens, and SVOC. Test chambers are constantly flooded with clean air to ensure complete air change after every 2 hours. Test chambers are kept at 23 ^oc in temperature and 50% of humidity. Measurements are performed after 3 days and 28 days by sampling and analyzing exhaust of test chambers.

Limit values of individual product are provided at https://www.emicode.com/en/limit-values/

GuT, European ecolabel applies to floor coverings. https://pro-dis.info/86.html

Inspection is conducted in 3 stages:

- Inspecting composition of prohibited toxic substances;

- Conducting emission test: requirement for woven fabric carpet: TVOC after 3 days aging in test chambers ≤ 500 µg/m³; or after 7 days aging in test chambers, VOC ≤ 210 µg/m³, VOC without LCI ≤ 85 µg/m³, R-value ≤ 1, SVOC (C₁₆-C₂₂) ≤ 30 µg/m³ and Formaldehyde <10 µg / m³

- Conducting odor test: circular specimens of 144 cm² aged at least 15 hours in airtight desiccators (approximately 2 liters in volume at 37 ^oC and 50% in humidity (humidity is adjusted by approximately 100 ml of magnesium nitrate)). A minimum 5 human test subjects (preferably 7 human test subjects) then evaluate odor intensity by quickly opening and closing desiccators. Odor intensity is given a score from 1 (odorless) to 5 (intensive). Intensity of odor produced by new materials must be < 4.

Nordic Swan ecolabeling program of Scandinavian countries

https://www.nordic- ecolabel.org/product-groups/

Ecolabeling program applies to floor coverings, indoor and outdoor partitions, furniture, and chipboard panels, threaded panels, gypsum panels, pressed panels, wooden panels.

Carcinogens, halogenated VOC, organic zinc compounds, phthalates, polybrominated diphenyl ethers, and substances causing mutation or harming human reproduction must not be present in soundproofing panels. Heavy metal must also not be present. Formaldehyde emission from finished products must be lower than 0,13 mg.m^-3 in indoor air.

Environmental chambers and emission chambers can be used.

Blue Angel labeling program of Germany.

https://www.blauer-engel.de/en/

This program labels the entire useful life of products, including flooring materials, furniture, and wall sheets. Auxiliary materials such as adhesives and covering materials are also included in program. This Program controls the emission of formaldehyde, TVOC, halogen organic substances, persistent toxic carcinogenic substances, mutagens, teratogenic. Tests conducted in standard environment chambers are necessary for certification of VOC emission from products. Emission requirements of flooring adhesives and other construction materials in test chambers are provided below.

Limit values:

3 day

28 day

TVOC (C₆ - C₁₆)

<1000 µg/m³ 10

<100 µg/m³ 10

TSVOC (> C₆ - C₂₂)

<50 µg.m^-3

C-substance

<10 µg m^-3 (total)

<1 µg.m^-3 (each substance)

Total VOC without LCI

< 40 µg/m³

Appendix G

(Reference)

Indoor air quality control program

G.1 Assignment of indoor air quality manager

Personnel experienced in aspects related to indoor air quality shall be assigned as indoor air quality manager who is responsible for developing and managing general indoor air quality program.

G.2 Development of indoor air quality dossiers of buildings

All existing documents and/or documents related to design, construction, operation, and maintenance of buildings and HVAC system are reviewed. Quick examination of the building (sample examination form under Appendix J) is conducted in accordance with indoor air quality measurement parameters under 4.2.

G.3 Handling of existing and potential indoor air quality issues

Contamination sources are identified; appropriate control measures defined under Appendix D are adopted.

G.4 Development and implementation of operation and maintenance plans

Plans for operation, backup maintenance, and irregular maintenance of HVAC systems and cleaning activities are developed and implemented.

G.5 Development and implementation of plans for specific activities

Procedures for renovating, supplementing, complementing, and altering occupancy of buildings, implementing insect control, and implementing other activities that may affect indoor air quality are developed and implemented.

G.6 Training building personnel pertaining to indoor air quality management

Personnel whose tasks and duties in regard to building management may affect indoor air quality must be equipped with knowledge relating to indoor air quality.

G.7 Communicating with building occupants about their role in maintaining acceptable indoor air quality

Building occupants must be informed about their activities that may affect indoor air quality and actions that they can do to maintain acceptable indoor air quality.

G.8 Development of indoor air quality-related complaint handling procedures

Coherent procedures for recording and handling complaints related to indoor air quality must be developed and made public to all building employees and occupants.

Appendix H

(Reference)

Information on indoor air contaminants, microbial pollutants, and mould handling guidelines

H.1 Common indoor air quality contaminants (see Schedule H.1)

Schedule H.1. Common indoor air quality contaminants

Indoor air contaminants

Common sources

Carbon dioxide

- Human exhalation

- Total combustion of materials

Carbon monoxide

- Partial combustion of materials

- Cooking fume

- Vehicle exhaust

- Tobacco smoke

Particulate matter/very fine particulate matter

- Partial combustion of materials

- Cooking fume

- Vehicle exhaust

- Tobacco smoke

- Interior particulate (paper, rug, curtain, fabric, interior furniture)

Formaldehyde/TVOC

- Wood furniture (plywood, chipboards)

- Organic cleaning agents, disinfectants

- Paint, lacquer

- Adhesives, glue, binders

- Aerosols, insecticides

- Cosmetics, perfume

- Fabric materials in carpet and wrapping

- Cleaning solutions

Ozone

- Ozone generator or ionizer

- Electrostatic filter

- Photocopy machine

- Laser printers

- Electric discharge

Mould

- Wet or damp carpet, curtain, wrapping

- Water leak (e.g. leak from condensation pipes via fissures, cracks)

- Condensation surface (e.g. poorly insulated gas/water pipes, interior surface that makes contact with moist air, evaporators, condensation trays, walls separating air-conditioned areas and non-air-conditioned areas)

- High humidity content environment

- Overwatered indoor plants

Bacteria

- Building occupants

- Stagnant water

- Decomposed food

- Insects, domestic animals

H.2 Causes of microbial contaminants of indoor environment

H.2.1 Bacteria

Dominant bacteria in indoor environment are gram-positive bacterial strains of Staphylococcus, Micrococcus, and Streptococcus emitting from the mouth, nose, and skin. Gram-negative bacterial can be diverse at time (e.g. Acinetobacter, Aeromonas, Flavobacterium, Pseudomonas) in the presence of significant sources of water such as: water trays, drain and saturated surface. Bacteria can also be found on biofilm developed on wet surfaces of heat exchangers. Thus, quick and effective maintenance of such system is important to prevent bacteria contamination.

Legionella pneumophila may occur as a result of damp aerosols spreading from sources of contaminated aerosols such as fountains, cooling towers, misting fans, showerheads, spa, Jacuzzis, etc. Regulations on community health environment (cooling towers, fountains) dictating frequency of bacterial measurement and permissible limit of Legionella must be developed.

H.2.2 Indoor mould

Moulds are classed as Fungi, unlike plants, lack chlorophyll, and sustain by digesting plant materials, using plants and other organic substances as sustenance.

Molds and fungi produce spores which can be easily distributed through the air. The majority of moulds found indoor comes from outdoor sources. They require the necessary humidity to develop and only become a problem in presence of excessive water, high humidity, or damp. Common indoor humidity sources that cause mould-related problem include waterlogged soil, damp soil, leakage from roof and water pipes, flooded basements, leakage from water pipes or condensation on cold surfaces. Showerheads and cooking fume may cause mould problems if ventilation does not suffice. Uncontrolled humidity can also act as a source of mould, especially in damp heat climate such as Vietnam.

Leakage should be repaired in a promptly manner; leaking equipment must be dried and cleaned or replaced within 24 hours. Materials that have been wet for more than 48 hours may facilitate mould growth.

Allergic reactions, similar to those of pollen exhibited in common animals, and irritation are one of the most common health problems in individuals sensitive to moulds. Possible symptoms are similar to the common cold and include skin rash. Moulds can also worsen asthma. Symptoms are temporary most of the time and can be treated by dealing with mould problems.

Each individual will react to mould infection in a different way. Individuals who are more vulnerable to moulds include: infants, toddlers, pregnant women, the elderly, individuals having respiratory diseases such as asthma, and or individuals having sensitivity issues or immunodeficiency.

H.2.2.1 Common indoor moulds

Common indoor mould spores are Cladosporium, Penicillium, and Aspergillus. Brief descriptions of these spores are provided below in Schedule H.2:

Schedule H.2 - Common indoor moulds

Cladosporium

Cladosporium is a type of outdoor mould and commonly found in nearby vegetation. Cladosporium cladosporioides and Cladosporium herbarum are species of phylloplane that appear in outdoor air at a high rate. In respect of indoor environment, Cladosporium spp. grows as secondary colonies on walls following primary colonies such as Penicillium and Aspergillus spp. Cladosporium is very common in damp construction materials.

Penicillium

Common species of Penicillium are usually found both indoor and outdoor. Various species of Penicillium cause damage to damp construction materials, including the Penicillium aurantiogriseum which is usually found in household bush.

Aspergillus

The species of Aspergillus is popular in damp heat climate. These species thrive on organic materials. Aspergillus is commonly present on construction materials. Aspergillus fumigatus is pathogenic and one of the main causes of aspergillosis.

H.2.2.2 Hidden moulds

Locations where hidden moulds may appear are walls behind furniture, thermal insulation, or cushion in ducts, pipes carrying condensation in AHU and roofing materials. Other locations include drywalls covered in vinyl wallpaper, wood panels, carpets which trap vapour and humidity.

H.2.3 Handling moulds

H.2.3.1 Mould pollution assessment

Mould pollution assessment should be conducted before any remediation task so as to identify:

a) Size of mould patches and/or humidity issues;

b) Damaged materials.

H.2.3.2 Remediation plans

Recommended remediation plans include:

a) Steps taken to remediate issues relating to water or humidity;

b) Steps taken to carefully cover and eliminate construction materials affected by moulds.

c) PPE and appropriate preventive measures are adopted.

H.2.3.3 Cleaning methods

Cleaning methods include:

a) Vacuuming wet dust on hard surfaces or cleaning carpets and covered furniture with steam;

b) Wiping and/or scrubbing with clean water and/or cleaning agents;

c) Vacuuming using HEPA filters after leaving to dry completely;

d) Removing damaged materials by sealing in plastic bags and later disposing as regular wastes.

H.2.3.4 PPE

Appropriate PPE should be worn to prevent inhalation of moulds and spores, contact with skin and eyes when cleaning.

When cleaning small areas (less than 3 m²), gloves, protective goggles, and N-95 masks are recommended.

In respect of larger contaminated areas, gloves, overalls, shoes wrappings, and respirators with HEPA filters are recommended. Protective goggles are required if half-face respirators are used.

H.2.3.5 Prevention

Appropriate preventive measures should be take to prevent the release of moulds into indoor environment and minimize mould exposure of repair personnel and building occupants.

Preventive measures are not required in small areas (less than 1 m²).

In respect of areas up to 3 m², polyethylene sheets shall be used to cover ceiling to floor to create containment space and maintain negative pressure in tandem with HEPA filters.

In respect of larger areas, two layers of polyethylene shall be required.

H.2.4 Preventing moulds in residential buildings

As a part of periodic maintenance, buildings should be inspected for areas damaged by water leakage and visible mould growth. Materials or areas damaged by water should be remediated as soon as possible (within 48 hours); building surfaces and furniture surfaces should be dried to prevent mould growth. Where any visible mould growth is observed, water/humidity sources that affect the growth must be removed then the mould growth can be eliminated.

Appendix I

(Reference)

Indoor air quality inspection guidelines

For the purpose of indoor air quality inspection and development of building indoor air quality dossiers, a four-step inspection procedures under Figure I.1 is recommended.

Indoor air quality inspection of existing buildings is recommended to be conducted once every 5 years in accordance with requirements of health and safety risk evaluation at residence and workplace.

In respect of new buildings and renovated rooms, indoor air quality should be inspected after construction and before operation.

I.1 Step 1 - Conducting quick general inspection

Quick general inspection of buildings and HVAC system shall be conducted by competent persons to identify irregularities. List of sample issues to be examined is provided under Appendix J and contain:

a) Layout drawings of buildings depicting details of all floors, locations of all cooling towers, and outdoor air inlets;

b) Diagraph of HVAC system;

c) HVAC system operation and maintenance schedule.

I.2 Step 2 - Collecting air sample and feedback from occupants

I.2.1 Measurement of indoor air quality parameters shall be carried out for 8 consecutive hours in public buildings and 24 consecutive hours in residential buildings. In respect of public buildings, sampling areas shall be measured under normal operating conditions where number of occupants equals 70% the actual occupant load. Where measurement in 8 consecutive hours or 24 consecutive hours is not feasible, alternative measurement method (where readings of half-hour measurements conducted 4 times per day in public buildings and 8 times per day in residential buildings) is also acceptable.

I.2.2 Feedback from occupants and management personnel of HVAC system pertaining to indoor conditions should be gathered. A sample questionnaire is provided under Appendix K which can be adjusted to practical demands.

I.3 Step 3 - Commencing data analysis

Indoor quality parameters shall be analyzed by comparing concentrations of contaminants with acceptable limits proposed under Schedule 1. The analysis must include investigation into possible scenarios when indoor air quality parameters are outside of recommended range.

I.4 Step 4 - Developing remediation actions

Based on measurement results, remediation measures shall be developed, implemented, and evaluated in terms of fulfillment and sustenance of acceptable indoor air quality.

Figure I.1 - Illustration of indoor air quality inspection method

Appendix J

(Reference)

Sample indoor air quality inspection form

Quick general inspection shall be carried out for all rooms, air-conditioning system, and ventilation system of buildings. The goal is to identify any irregularity. The form provided below should be considered a guidelines and by no mean comprehensive. Assistance from building managers shall be required when necessary.

1. Level of contact and comfort of occupants

1.1 Is indoor temperature controlled by air-conditioning units? Are the air-conditioning units installed in the right locations? Are they properly located after building renovation? Are they configured at the appropriate temperature? Are they calibrated on a regular basis?

1.2 Do occupants experience discomfort due to thermal radiation from exterior walls that receive sunlight? Or from other heat sources?

1.3 Is every position in the room ventilated? Is there any dead corner in the room? Smoke detector tubes shall be employed.

1.4 Do occupants sit directly below air diffusers?

1.5 Is the building being used in accordance with design occupancy? Is there any wall/partition added or removed? Does use frequency change?

1.6 Is any flexible pipe twisted?

2. Potential pollution sources

2.1 Does any device produce gas or smoke? If yes, are these devices outfitted with stand-alone exhaust extraction system? Does exhaust spread to outdoor spaces or into corridors or air-conditioning system?

2.2 Do furniture, objects, carpets, etc. produce noticeable odor? Is cleaning agent, insecticide, or other chemical used indoor?

2.3 Is any part of the building undergoing renovation? Does renovation work take place during working hours? Are air-conditioning ducts properly sealed to prevent infiltration to other areas?

2.4 Are there kitchens or pantries and cooking areas present? Are these rooms equipped with ventilation system?

2.5 Are buildings adequately cleaned? Are furniture, office supplies, shelves, etc. frequently dusted to keep dust content to a minimum? Are carpets cleaned frequently?

3. Air-conditioning and ventilation

3.1 How many air outlets and inlets are there in each room or area? Is each room equipped with at least one air inlet?

3.2 Are air inlets and outlets located in positions that allow optimal air flow?

3.3 Are air inlets and outlets obstructed by compartmentalizing partitions or structures?

3.4 Is air-conditioning system turned off at any time in the day?

3.5 Are air-conditioning systems turned off after office hours? Are there employees in the building after office hours?

3.6 Where are outdoor air intakes located? Are they closer to cooling towers of the building or cooling towers of adjacent buildings? Are they close to outlets from the kitchens? Are they located at street elevation or close to a parking lot? Are they obstructed? Are there nay heavy industry facility nearby? Are there any active construction work nearby? Is outdoor air moved indoor?

3.7 Are filters used? Are they adequate? Is by-pass system available? Are they replaced or maintained in a timely manner?

3.8 Are there frequent cleaning and maintenance schedules of air-conditioning system? Are all parts of air-conditioning system frequently checked for leak, defects, etc.?

Appendix K

(Reference)

Survey form for building occupant

1 Personal information

1.1 Gender: Male / Female

1.2 Age:

1.3 Number of years working in the building:

2 Environment conditions

2.1 Year in which the building is built:

2.2 Type of building: office/shopping center/school/other

2.3 Grade of building

2.4 Type of office: Closed / Open

2.5 Carpeted floor: Yes / No

2.6 Papered wall: Yes / No

2.7 Infiltrated by tobacco smoke: Yes / No

2.8 Infiltrated by vehicle exhaust: Yes / No

2.9 Number of occupants in your room: _________________________

2.10 What is the type of air-conditioning unit at your working position?

Centralized air-conditioning unit / Localized air-conditioning unit

2.11 How is your working space illuminated?

Fluorescent light / Non-fluorescent light / LED light

2.12 Please state whether you work with or near the following devices:

Photocopy machine: Yes / No

Server: Yes / No

Air purifier: Yes / No

Other equipment (please specify: _____________________ )

2.13 How often do you have to wear extra clothes?

Frequently / Occasionally / Never

2.14 Does the air feel heavy?

Frequently / Occasionally / Never

2.15 Does the air reek of foul odor?

Frequently / Occasionally / Never

2.16 Are surfaces covered by visible moulds? Yes / No

2.17 Is there dust build-up in air inlets and outlets? Yes / No

3 Profession specific

3.1 Number of hours per day you work with computer at workplace: _______________

3.2 Evaluate the stress you feel at your working conditions:

Physical stress: Low / Moderate / High;

Mental stress: Low / Moderate / High;

Cooperation tendency in work: Low / Moderate / High

3.3 What is your type of job?

Management / Specialization / Secretary / Documentation / Other (specify: ___________ )

4 Health complaints

4.1 Please state your health symptoms at workplace in the past month:

Nasal congestion: