Indoor Air Quality


The United States Environmental Pollution Agency (EPA) describes Indoor Air Quality (IAQ) as “the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants”. The perceived comfort experienced by occupants of an indoor environment can be influenced by parameters such as temperature, air movement and relative humidity, whereas the health of occupants can be affected by the presence and concentration of indoor air pollutants.

The World Health Organisation (WHO) provides guidelines for three groups of indoor air pollutants of concern to public health, namely biological indoor air pollutants, chemical pollutants and pollutants from indoor combustion of fuels. Poor IAQ occurs when these parameters are not in compliance with the respective regulated or recommended limits.

Health Effects Associated With Poor Indoor Air Quality

Occupants of indoor environments where poor IAQ prevails may experience symptoms such as headache; eye, nose, throat or skin irritation; fatigue; shortness of breath; hypersensitivity and allergies; sinus congestion; dizziness or nausea. Sick Building Syndrome refers to a condition where these health effects are experienced only when occupying the building, without a specific illness or cause being identified. Air temperature, air velocity and relative humidity may contribute to this condition.

Where a specific cause or illness can be identified as the cause of symptoms experienced, such as Legionnaires Disease, it is referred to as a Building-Related Illness.

Thermal Comfort

Air temperature, air velocity and relative humidity contribute to thermal comfort, which is obtained in an indoor environment when the majority of occupants perceive the thermal environment as satisfactory (not too hot, not too cold, sufficient air flow, etc.). When thermal comfort is not achieved, it may cause increased employee complaints and lower productivity.

Standards often utilised to assess indoor air quality at a workplace include The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) Standard 55 – 2010: Thermal Environmental Conditions for Human Occupancy, and ASHRAE Standard 62.1 – 2013: Ventilation for Acceptable Indoor Air Quality Standard. Parameters that will typically be measured when assessing IAQ will include Carbon monoxide, Carbon dioxide, Relative humidity, Air temperature and Air velocity.

Biological Indoor Air Pollutants

(WHO guidelines for indoor air quality: dampness and mould.)

Chemical Pollutants in Indoor Environments

Chemical pollutants which may pose a risk to the health of occupants of indoor environments and are known to have indoor sources include Benzene, Carbon monoxide, Formaldehyde, Naphtalene, Nitrogen dioxide, Polycyclic aromatic hydrocarbons (PAH), Radon, Trichloroethylene and Tetrachloroethylene.

Pollutants from Indoor Combustion of Fuels

A large number of households, mostly from low- or middle income countries, still rely on the combustion of solid fuel for cooking, heating and lighting purposes. Occupants of these households, which typically include children and the elderly may be exposed to the pollutants emitted due to combustion. Health effects associated with exposure may include respiratory and cardiovascular diseases and cancer. Emission rate targets was set by the WHO for particulate matter with an aerodynamic diameter of less than 2.5 µg (PM2.5) and carbon monoxide (CO), which is the two main products of incomplete combustion.

Control of Indoor Air Quality

Suitable control measures to improve IAQ in an environment will depend on the specific environment, and the pollutants that were identified to be present. As a minimum every indoor environment should be ventilated either naturally or mechanically in such a way that the air breathed by employees does not endanger their safety, and that the concentration of any harmful substance therein is kept below the prescribed limits.


  1. United States Environmental Protection Agency. (Accessed 31 January 2018)
  2. OSH Answers Fact Sheets: Indoor Air Quality. Canadian Centre for Occupational Health and Safety. (Accessed on 23 May 2017)
  3. WHO guidelines for indoor air quality: dampness and mould. Copenhagen, WHO Regional Office for Europe, 2009 (Accessed 31 January 2018)
  4. WHO guidelines for indoor air quality: selected pollutants. Copenhagen, WHO Regional Office for Europe, 2010 (Accessed 31 January 2018).
  5. WHO guidelines for indoor air quality: household fuel combustion. Geneva, World Health Organisation, 2014 (Accessed 31 January 2018).
  6. Environmental Regulations for Workplaces,1987. Occupational Health and Safety Amendment Act No 85 of 1993.Department of Labour of South Affrica.