Is indoor air quality (IAQ) a health and safety concern?Indoor air quality has become an important occupational health and safety issue. Energy conservation measures instituted in early 1970's often led to reduced intake of outside air and increased the potential for build-up of internally generated air pollution.
People working indoors often experience symptoms such as headaches, shortness of breath, coughing or nausea just to mention a few. However, it is rarely possible to prove that these symptoms are related to a particular indoor air contaminant. In fact, building occupants are simultaneously exposed to a wide range of indoor air contaminants.
What are the common causes of IAQ problems?IAQ problems result from interactions between building materials and furnishing, activities within the building, climate, and building occupants. IAQ problems may arise from one or more of the following causes:
- Indoor environment - inadequate temperature, humidity, lighting, excessive noise
- Indoor air contaminants - chemicals, dusts, moulds or fungi, bacteria, gases, vapours, odours
- Insufficient outdoor air intake
What are indoor air contaminants?Here are examples of common indoor air contaminants and their main sources:
- Carbon dioxide (CO2), tobacco smoke, perfume, body odours -- from building occupants.
- Dust, fibreglass, asbestos, gases, including formaldehyde -- from building materials.
- Toxic vapours, volatile organic compounds (VOCs) -- from workplace cleansers, solvents, pesticides, disinfectants, glues.
- Gases, vapours, odours -- off-gas emissions from furniture, carpets, and paints.
- Dust mites -- from carpets, fabric, foam chair cushions.
- Microbial contaminants, fungi, moulds, bacteria, -- from damp areas, stagnant water and condensate pans.
- Ozone -- from photocopiers, electric motors, electrostatic air cleaners.
What symptoms are often linked to poor indoor air quality?It is common for people to report one or more of the following symptoms:
- dryness and irritation of the eyes, nose, throat, and skin,
- headache,
- fatigue,
- shortness of breath,
- hypersensitivity and allergies,
- sinus congestion,
- coughing and sneezing,
- dizziness, and/or
- nausea.
People generally notice their symptoms after several hours at work and feel better after they have left the building or when they have been away from the building for a weekend or a vacation.
All of these symptoms, however, may also be caused by other factors, and are not necessarily due to poor indoor air quality.
What are some related health issues?Occupants of buildings with poor IAQ report a wide range of health problems which are often called Sick Building Syndrome (SBS) or Tight Building Syndrome (TBS), Building-Related Illness (BRI) and Multiple Chemical Sensitivities (MCS).
The term sick building syndrome (SBS) is used to describe cases in which building occupants experience adverse health effects that are apparently linked to the time they spend in the building. However, no specific illnesses or cause can be identified.
Building-Related Illness (BRI) refers to less frequent (but often more serious) cases of people becoming ill after being in a specific building at a certain time. In these cases, there is usually a similar set of clinical symptoms experienced by the people and a clear cause can often be found upon investigation. Legionnaires Disease is an example of BRI caused by bacteria which can contaminate a building's air conditioning system
A certain percentage of workers may react to a number of chemicals in indoor air, each of which may occur at very low concentrations. Such reactions are known as multiple chemical sensitivities (MCS). Several medical organizations have not recognized multiple chemical sensitivities. However, medical opinion is divided, and further research is needed.
Is air contamination the only cause of these symptoms?No. Feelings of discomfort and illness may be related to any number of issues in the total indoor environment. Other common causes may include noise levels, thermal comfort (temperature, humidity, and air movement), lighting, and ergonomics. It is important that all possible causes be investigated when assessing complaints.
Other OSH Answers documents on these topics include:
Why do only some people seem to develop symptoms?As with any other occupational illness, not all people are affected with the same symptoms or to the same extent. The more sensitive or more exposed people will often experience symptoms earlier than other people. As air quality deteriorates and/or the length of exposure increases, more people tend to be affected and the symptoms tend to be more serious.
Can a person become sensitive to IAQ contaminants as time passes?It seems possible. Some people may not be sensitive to IAQ problems in the early years of exposure but can become sensitized as exposure continues over time.
When should I start suspecting that IAQ may be a problem?When there is a problem with IAQ, people may experience various health conditions that are listed above. Since many of the symptoms are very similar to what we feel like when coming down with a cold or the flu (influenza), it is often difficult to say for sure if indoor air is the cause of the symptoms.
However, it would be prudent to investigate IAQ if people develop these symptoms within a few hours of starting the workday and feel better after leaving the building, or after a weekend or vacation. In addition, if many people report similar symptoms, or if all of the people reporting symptoms work in the same area of a building, air quality should be suspected.
Are there laws or guidelines for IAQ?Many Canadian jurisdictions do not have specific legislation that deals with indoor air quality issues. In the absence of such legislation, the "general duty clause" applies. This clause, common to all Canadian occupational health and safety legislation, states that an employer must provide a safe and healthy workplace. Thus, making sure the air is of good quality is the employer's duty.
Several organizations* have published recommended guidelines for indoor air quality. For example:
In addition, IAQ is implied in most building codes as design and operation criteria. Building codes in Canada and the U.S. generally refer to the American Society of Heating, Refrigerating, and Air Conditioning Engineers* (ASHRAE) Standard 62 "Ventilation for Acceptable Indoor Air Quality" (1989 or 1999 version may be cited), CSA International* Standard Z204-94 "Guideline for Managing Indoor Air Quality in Office Buildings", or other acceptable standards.
(*We have mentioned these organizations as a means of providing a potentially useful referral. You should contact the organizations directly for more information about their information and/or services.)
Why can't I use "regular" chemical occupational exposure limits for indoor air contaminants?It is not recommended that "regular" occupational exposure limits (e.g., OELs, TLVs®, PELs) be used to determine if the general indoor air quality meets a certain standard. Occupational exposure limits listed in health and safety regulations and the Threshold Limit Values® (TLVs) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) are intended as a guide to prevent illness or certain effects (like eye and nose irritation) in industrial situations. These limits may not be appropriate in office settings or for the home.
Occupational exposure limits use dose-response data which show the health effects of repeated exposure to one specific chemical. Similar data is not available for long-term, low-level exposures to a combination of contaminants as is the case for IAQ problems. Currently, there is not enough information available to predict the effects of exposure to several potentially harmful agents at the same time.
How do I investigate possible IAQ problems?Typicaly people will report that they are experiencing symptoms believed to be caused by IAQ. Unfortunately finding the source or cause can often be difficult. The steps taken may vary from situation to situation but will include:
- Investigate the ventilation system to make sure it is operating properly (e.g., the right mix of fresh air, proper distribution, filtration systems are working, etc.).
- Look for possible causes (e.g., source of a chemical, renovations, mould, etc.).
- Rule out common causes of the symptoms such as noise, thermal comfort, humidity, ergonomics, lighting, etc.
- Conduct a survey to help pin-point work conditions and practices (see below for a sample survey).
- Consider air testing by a qualified professional.
What is an example of a health survey that I can use to help identify if IAQ is related to reported problems?The following is a sample of a questionnaire that could be used to help identify if an office or building has an indoor air quality problem.
- Use this questionnaire in consultation with a health and safety professional or other expert(s).
- Modify or customize this questionnaire to address the conditions and work practices at to your workplace.
- Analyze the responses in consultation with an expert.
SAMPLE HEALTH SURVEY (Adapted from: "Indoor Air Quality Health and Safety Guide" Prepared by CCOHS)
1. What is your present job? __________________________________
2. How long have you been doing this job? ______________________
3. In the last year, did you experience any of the following health symptoms that lasted two days or more?
Health Symptoms | Yes, frequently | Yes, sometimes | No, never |
| Headache | | | |
| Nausea | | | |
| Dizziness | | | |
| Tiredness / fatigue | | | |
| Irritation of eyes, nose, throat | | | |
| Breathing Problems | | | |
| Stuffy or runny nose | | | |
| Sinus congestion | | | |
| Coughing | | | |
| Sneezing | | | |
| Wheezing | | | |
| Shortness of Breath | | | |
| Blurred Vision | | | |
| Difficulty in concentrating | | | |
| Other: | | | |
If you answered NO to all of these questions, stop here.
4. On average, when you notice the symptoms, how long have you been at work?
Less than 1 hour____ 2 - 4 hours ________ More than 4 hours _____
5. Are the symptoms at work _____ than when you are at home? (Circle one)
better / the same / worse
6. After work or the end of your shift, are the symptoms ______? (Circle one)
better / the same / worse
7. After a week away from work, are the symptoms ______ ? (Circle one)
better / the same / worse
8. Did the symptoms cause you to take time off from work? (Circle one)
Yes / No
9. How much do the symptoms interferes with the following:
Rank on a scale of 1 to 10 with 1 meaning "none", and 10 meaning "very intense"
A) your work: ____
B) your life outside of work: ____
C) your sleep: ____
10. Have you noticed any of the following conditions?
Physical Conditions | Yes, frequently | Yes, sometimes | No, never |
| Are there any unusual or unpleasant odours in the building? | | | |
| Does the air seem stuffy? | | | |
| Is the air dry? | | | |
| Do you get shocks from static electricity? | | | |
| Is the work area too warm? | | | |
| Is the work area too cool? | | | |
| Does the temperature vary from room to room? | | | |
| Is it drafty where you work? | | | |
11. Are you aware of any of the following contaminants are in your building or being produced nearby?
| ammonia |
| | asbestos |
| | carbon dioxide |
| | carbon monoxide |
| | fibreglass |
| | formaldehyde |
| | methyl alcohol |
| | microorganisms (such as viruses, bacteria, mildew or other fungi) |
| | mercury |
| | motor vehicle exhaust |
| | nitrogen oxides |
| | ozone |
| | paint vapours |
| | perfumes, hair sprays |
| | pesticides |
| | polychlorinated biphenyls (PCBs) |
| | radon and its decay products |
| | solvent vapours |
| | sterilant gases (such as ethylene oxide) |
| | sulfur oxides |
| | tobacco smoke |
| | others that you know about or suspect |
12. Do you think any of the following might be causing the IAQ problems?
| air circulation |
| | humidifier |
| | air conditioning |
| | temperature |
| | humidity |
| | noise |
| | illumination |
| | foul odours |
| | air circulation shut down on weekends and evenings |
| | irritants in the air |
| | outdoor contaminants entering the building (please specify) |
| | machinery/equipment (e.g. laser printers, photocopiers) |
| | smoking |
| | overcrowding |
| | dividers |
| | renovations |
| | pesticide spraying |
| | new furnishing/ carpets |
| | others (please specify) |
| | I don't know |
13. Please make any comments or suggestions about how your job affects you and how to correct any problems in your workplace.
What should I do if I suspect that I am ill from poor IAQ? If you think that you may be ill from IAQ problems, it is important to keep track of when you get your symptoms (aches, pains, headaches, etc.) and when they go away. This record will help your safety officer or health professional determine what the problem is related to. You may also wish to discuss you symptoms with your health professional to rule out any other medical conditions.
As with any other occupational health and safety concern, you can discuss your concerns with the health and safety representative, the health and safety committee, your supervisor, safety co-ordinator, industrial hygienist, or any other member of your company that is responsible for health and safety.
Your local government jurisdiction may also be able to provide information and advise on workplace health and safety.
Document last updated on February 9, 2006
Copyright ©1997-2006 Canadian Centre for Occupational Health & Safety
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