Washington , Nov 17: A new study by NASA has estimated that aerosol (particulate) pollution at ground level in the United States originates from regional sources and only a small amount is brought to the country from other parts of the world.

Aerosols are airborne particles that arise from both human sources such as burning fossil fuels, and natural sources such as fires, dust and volcanoes. They are also a major source of near-ground pollution.

Previously, researchers studying aerosols moving between continents focused primarily on tracking a single type of aerosol, such as dust or black carbon, or measuring their quantities throughout the atmosphere.

This left a gap in understanding where ground-level particulate pollution comes from.

But the new research, using an innovative global aerosol tracking model, has for the first time produced a global estimate of sources and movements of aerosols near the ground where they can affect human health and run afoul of environmental regulations.

"This is the first study to comprehensively consider the origin, composition and type of fine particles over the United States and connect them to both domestic and foreign sources." said Mian Chin, an atmospheric scientist at NASA's Goddard Space Flight Center and also the lead author of the study.

When the research was started upon, scientists set out to investigate how much and what types of aerosols were making the intercontinental journey into US shores.

For this, the research team employed the help of a computer model using known air chemistry and wind patterns to trace a region's aerosols (which included everything from fossil fuel and biofuel combustion, biomass burning, and volcanic sources, desert dust and sea salt) back to their sources.

"Using the model, we followed the path of aerosols to find out how much is local and how much is from outside a region," said Chin.

But the results of the study revealed something completely different.

The first finding of the research was that 65-70 percent of surface particulate matter in the eastern US originates from regional aerosol pollution from fuel combustion in North America. The research team also found that 30-40 percent of fine particulates in the western U.S. come from local pollution sources.

The model results estimated that just 2-6 percent of US surface fine particulates come from fuel combustion particles emitted outside of North America, including Asia and Europe.

It was also found out that about 50 percent of surface fine particulate matter in the western U.S. stems from a natural source: dust transported from Asia or from local deserts and organic aerosols from vegetation.

"Our results indicate that controlling regional pollution emissions will be the most effective and most responsible way to manage US air quality," said Chin. (ANI)