Climate change will have a direct impact on indoor air quality by increasing exposure to indoor risks; and by amplifying the environmental determinants of indoor risks.
Exposure to indoor risks
- Due to changing weather and climate patterns (heat waves, cold spells, heavy rain and storms) people will spend more time indoors. This is particularly true in the case of more vulnerable population groups such as elderly people and children.
- Severe storms and flooding frequently result in power outages and the breakdown of heating and cooling systems, and may even force people to leave their homes. In combination with abnormal temperatures, power failures will contribute to thermal stress that can affect health and exacerbate discomfort in settings that rely exclusively on mechanical ventilation and air conditioning. The use of alternative sources of heating may increase the risk of indoor carbon monoxide poisoning. The relocation of families to temporary housing or emergency shelters may increase their exposure to indoor air contaminants in substandard constructions. Increased exposure to mouldy indoor environments among unprotected workers, first responders, homeowners and volunteers is likely during the restoration of damaged buildings after hurricanes, typhoons, tropical storms and flooding. The overuse of air conditioning during heat waves may lead to increased exposure to microbial contaminants that grow on the moist components in air-conditioning systems. Power outages will also affect the mechanical mitigation systems installed in buildings that are exposed to harmful levels of radon.
- Exposure to bioaerosols and VOCs will increase due to decreased ventilation and greater relative humidity as a result of inadequate building adaptation measures.
Amplification of environmental impacts
- Heat waves and droughts can be expected to lead to more wild fires, which will result in temporary huge increases in airborne particles and a substantial increase in gaseous air pollutants. These will infiltrate into the indoor air, increasing the risk of exposure.
- The intrusion of water into buildings due to flooding, or after storms as a result of failures in the building envelope and damage to water pipes, will increase dampness, facilitating mould growth on internal surfaces.
- Changes in temperature patterns and moisture levels will lead to an increase in the number and geographical distribution of disease vectors and indoor pests, requiring the more intense use of chemical pesticides and thus adding to the burden of persistent pollutants.
- Climate change will influence the concentration and toxicity of biological and chemical pollutants in the ambient air (e.g. pollen, allergens, ozone and particulate matter), which will increasingly infiltrate the indoor environment.