Over the last decade there has been increasing awareness of indoor air quality issues in residential, commercial, and industrial environments. Increasing knowledge of air contaminants has indicated the importance of their influence on human health.

Indoor air quality is comprised of three factors: physical, chemical and biological. Health effects vary from acute to chronic and from mild to severe.

Physical Factors

The physical factors influencing indoor air quality include levels of particulates and the presence of asbestos.

Particulates such as dust can be irritating and cause short- and long-term effects. The majority of particulates are combustion products or particles released through physical disruption. Examples of particulates are coal dust, smoke, and road dust.

Exposure to asbestos through inhalation can result in long-term impairment of the respiratory system, cancer, and ultimately death. Other effects include a build-up of scar tissue in membranes surrounding the lungs, pulmonary hypertension, and immunological effects.

Chemical Factors

Chemicals of concern in indoor air include VOCs (volatile organic compounds), carbon monoxide, and ozone. These chemicals can cause:

• Eye, nose, and throat irritation
• Headache, nausea
• Nerve problems
• Cancer
• Biological Factors

The type and severity of the response depends greatly on the nature of the chemical and the sensitivity of the individuals exposed.

Biological Factors

The presence of certain types of bacteria and moulds in indoor air can pose a biological threat based on pathogenicity, toxicity, and allergenicity.

Airborne microorganisms, such as Legionella , are able to cause disease. Other microbes, such as Aspergillus fumigatus and Stachybotrys chartarum are able to produce toxins that cause deleterious effects. Numerous other species are able to induce allergic reactions in susceptible individuals.