Black carbon, also commonly known as soot, is a component of fine particulate matter (PM2.5). It is formed by the incomplete combustion of wood and fossil fuels, a process that also creates carbon dioxide (CO2), carbon monoxide, and volatile organic compounds. These particles can deposit deep in the lungs, potentially even reaching the bloodstream, due to their small size. Inhalation of black carbon is associated with a range of health issues, including respiratory and cardiovascular problems, and an increased risk of lung cancer.

Black carbon is also a top contributor to global warming because it is very effective at absorbing light. It exacerbates the warming of the air and surfaces in regions where it is concentrated, altering weather patterns and ecosystem cycles. It stays in the atmosphere for only days to weeks but significantly impacts the climate, snow and ice, agriculture, and human health. 

This winter, the Spokane Regional Clean Air Agency (Spokane Clean Air) is completing a study focused on identifying black carbon pollution “hotspots” in Spokane’s East Central and Chief Garry Park neighborhoods using federal grant funding. These areas, with their high population density and proximity to major traffic corridors, provide an ideal setting for examining local sources of black carbon.

By conducting this study, Spokane Clean Air aims to gain an understanding of the contributions of traffic and wood burning to PM2.5 pollution in Spokane County.

“This information will inform the design of the agency’s air monitoring network and provide guidance for current and future agency programs,” said Mark Rowe, Monitoring Manager at Spokane Clean Air. “We hope to use this information to reduce PM2.5 pollution in Spokane.”

Spokane Clean Air is using an air pollution monitor called an Aethalometer to conduct the study, which differentiates the proportion of black carbon particles emitted by traffic and diesel engines from that emitted by wood burning or other biomass burning. A portable PM2.5 monitor is operated alongside the Aethalometer which enables the comparison of black carbon and PM2.5 concentrations in the area.

The black carbon study builds on Spokane Clean Air’s existing initiatives to reduce pollution across Spokane County. These include programs such as school No-Idle Zones, the wood stove change-out program, and a past effort to reduce idling by supporting locomotive engine Hotstart retrofits to reduce diesel emissions.