Air pollution is a mixture of natural and man-made substances in the air we breathe. It is typically separated into two categories: outdoor air pollution and indoor air pollution.
Outdoor air pollution involves exposures that take place outside of the built environment. Examples include:
- Fine particles produced by the burning of fossil fuels (i.e. the coal and petroleum used in energy production)
Noxious gases (sulfur dioxide, nitrogen oxides, carbon monoxide, chemical vapors, etc.)
Ground-level ozone (a reactive form of oxygen and a primary component of urban smog)
Indoor air pollution involves exposures to particulates, carbon oxides, and other pollutants carried by indoor air or dust. Examples include:
- Gases (carbon monoxide, radon, etc.)
Household products and chemicals
Building materials (asbestos, formaldehyde, lead, etc.)
Outdoor indoor allergens (cockroach and mouse dropping, etc.)
Mold and pollen
In some instances, outdoor air pollution can make its way indoors by way of open windows, doors, ventilation, etc.