Indoor air quality has become an important occupational health and safety issue. In the past few decades, energy conservation measures have led to airtight building construction that can create problems with IAQ. Frequently the ventilation systems are set to minimize the amount of fresh air entering and circulating within the building. This restriction impacts indoor air by allowing a build-up of air contaminants within the building that are not properly removed.
People spend a lot of time indoors -- for example, many office workers will spend their entire working day inside buildings. 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.
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:
Here are examples of common indoor air contaminants and their main sources:
It is common for people to report one or more of the following symptoms:
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.
Many of these symptoms may also be caused by other health conditions including common colds or the flu, and are not necessarily due to poor IAQ. This fact can make identifying and resolving IAQ problems more difficult.
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.
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:
As with any other occupational illness, not all people are affected with the same symptoms or to the same extent. Some people may be more sensitive than others. Some people may be exposed to more contaminants in the building than others and they may 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.
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 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.
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, Health Canada has prepared a number of publications on air quality. In the United States, the Occupational Safety and Health Administration (OSHA) has compiled information on Indoor Air Quality.
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 62.1-2010 - Ventilation for Acceptable Indoor Air Quality (or previous versions), or other acceptable standards.
It is important to understand that most IAQ standards and guidelines are established to ensure the comfort of workers. So these values tend to be lower than regulatory values that are set to protect workers from possible health based hazards.
*We have mentioned these organizations as a means of providing a potentially useful referral. You should contact these organizations directly for more information.
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.
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:
Many people may play a role in helping to resolve an IAQ problem including the building owner, employer, property manager, and occupants. Who conducts your investigation will depend on your workplace, but in general, you should have one person who is the leader, and perhaps a small team, including a representative from the work site health and safety committee, or the union, if appropriate. The expertise of many other people such as health and safety or building maintenance personnel, and the experience of everyone in the workplace will all be important in finding the root cause of your IAQ problem.
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.
SAMPLE HEALTH SURVEY (Adapted from: Indoor Air Quality Health and Safety Guide, prepared by CCOHS)
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 July 4, 2011