SCIENTISTS last week unveiled the most complete view of global air pollution ever assembled — moving pictures that chart concentrations of carbon monoxide as they pass over oceans and continents. The false-colour imagery was captured by a Canadian instrument on NASA’s Terra satellite.

The colour-coded images show reddish hot spots of carbon monoxide emissions rising from fires in the forests and grasslands of Africa, South America and the western United States. Wintertime monitoring of the Northern Hemisphere pointed up higher levels of air pollution caused by the burning of fossil fuels for home heating and transportation.

Carbon monoxide is a byproduct of burning organic matter such as wood, as well as incomplete fossil-fuel combustion. By tracking plumes of carbon monoxide, scientists can follow the movements of other pollutants such as nitrogen oxides that are produced by the same processes but cannot be directly detected from space.

NASA said data from the Canadian-built experiment aboard Terra — known as Measurements of Pollution in the Troposphere, or MOPITT — could give policymakers and scientists a way to identify major sources of air pollution.

While Terra travels around the earth 16 times a day in a pole-to-pole orbit, MOPITT detects carbon monoxide in the atmosphere at levels of two to three miles above the surface. At that level, the substance interacts with other gases and forms ozone, which is itself a greenhouse gas and a human health hazard. The pollutants may move upward to altitudes where it can be blown rapidly over great distances or they may move downward to the surface.

The readings from MOPITT were processed by a team at the US National Centre for Atmospheric Research, based in Boulder, Colorado. Researchers found that about half of the global emissions of carbon monoxide came from human activities.

“With these new observations, you clearly see that air pollution is much more than a local problem,” John Gille, MOPITT principal investigator at the Colorado centre, said in a written statement. “Much of the air pollution that humans generate comes from natural sources such as large fires that travel great distances, and affects areas far from the source.”

Gille said he was surprised to see a strong source of carbon monoxide in Southeast Asia, often generating a plume that spread across the Pacific to North America. He suspects that the plume arises from industrial sources as well as fires.

The Terra satellite, considered the flagship of NASA’s Earth Observing System, was launched in December 1999 from Vandenberg Air Force Base, California, atop an Atlas 2AS rocket. It began its scientific observations in February 2000. The $1.3-billion mission is due to last six years.

Wednesday’s release of MOPITT imagery came at the American Geophysical Union’s spring meeting in Boston.