Particulate pollution's origins affect its impact on climate and human health

Aug. 17 (UPI) -- The effects of particulate matter on climate and human health is dependent on the pollution's origin, new research showed.

The lifespan of particulates is highly variable. The length of time particulate matter spends in the atmosphere depends on when and where pollution particles are emitted.

Particulate matter -- car exhaust, factory soot, sulfates, aerosols and more -- is the deadliest type of air pollution. Studies have linked particulate pollution with a variety of human ailments, including lung disease, heart disease and cancer. One study showed particulate pollution is responsible for 5.5 million deaths annually.

But particulate matter also affects climate. Pollution particles reflect sunlight, cooling temperatures.

But not all particulate matter is created equally, and according to a new study, climate models have failed to account for the variability engendered by pollution's origins.

"Aerosols emitted in the middle of a monsoon might get rained out right away, while emissions over a desert might stay in the atmosphere for many days," Ken Caldeira, researcher at the Carnegie Institution for Science, said in a news release. "So far, policy discussions have not come to grips with this fact."

Particle pollution in Europe and North America has a larger impact on climate than particulates emitted in India, but data suggest aerosol emissions in Europe and North America are declining, while particulate pollution in India and Africa is on the rise.

"This means that the degree to which aerosol particulates counteract the warming caused by greenhouse gases will likely decrease over time as new countries become major emitters," said Carnegie's Geeta Persad.

Without particle pollution, global temperatures would be significantly warmer. Models suggests aerosols have neutralized roughly a third of CO2-driven warming since the mid-20th century.

Researchers hope their work -- detailed in the journal Nature Communications -- will inspire policy makers and regulators to pay closer attention to regional differences when crafting pollution mitigation strategies.

"Just as aerosols' climate effects are strongly dependent on source region, we also expect their health and other air quality effects to be dependent on their origin," explained Persad. "Moving forward, we want to understand this air quality piece and the implications it could have for optimizing local air pollution mitigation."