An air emissions inventory is an accounting of the amount of air pollution emitted by various sources. Every year, Ecology and the local clean air agencies inventory facilities with air operating permits. This is called a point source inventory. Every three years, Ecology inventories many additional sources such as motor vehicles, wood stoves, outdoor burning, agriculture, and natural sources. Several inventory summaries are available below.

Associations between air pollution and a multitude of health effects are now well established. Given ubiquitous exposure to some level of air pollution, the attributable health burden can be high, particularly for susceptible populations.

Risk assessment provides a framework for combining and evaluating scientific data on source-to-health effects for contaminants that could potentially affect the health of human populations. It utilizes an integrated approach to hazard identification, dose response, exposure assessment, and risk characterization. Since the range of potential exposure scenarios is considerable, given the complexity of wood-smoke sources and emissions, there is a need for defining the critical characteristics for the key parameters leading to adverse health outcomes

The sentiment that woodsmoke, being a natural substance, must be benign to humans is still sometimes heard. It is now well established, however, that wood-burning stoves and fireplaces as well as wildland and agricultural fires emit significant quantities of known health-damaging pollutants, including several carcinogenic compounds. Two of the principal gaseous pollutants in woodsmoke, CO and NOx, add to the atmospheric levels of these regulated gases emitted by other combustion sources. Health impacts of exposures to these gases and some of the other woodsmoke constituents (e.g., benzene) are well characterized in thousands of publications.