As smoky air from Canada’s wildfires shrouds broad swaths of the U.S., here are seven facts you should know about measuring air quality.
"We can get very strong inversions in mountainous regions, for instance, and an inversion is very good at trapping pollutants down to the surface," said Joost de Gouw, a chemistry professor at the University of Colorado Boulder and a fellow at the Cooperative Institute for Research in Environmental Sciences. "So in a lot of areas – for instance, in Salt Lake City – the air quality is the worst in the winter because the airspace is trapped.
An inversion is when temperatures rise with height, with warm air sitting overtop of colder air below. Since cold air is denser than warm air, it is trapped near the Earth’s surface. Some areas will issue air quality burn bans when fireplace smoke could become an issue during strong wintertime inversions.Most people think air pollution comes from car exhaust or industrial production, and this is a correct assumption. Wood smoke from eitheror home fireplaces can also contribute to degraded air quality due to an increase in tiny particles in the air.
But the sources of air pollution have changed over the years, scientists say, because of some tighter regulations. "I would say 20 years ago, the top three were transportation/motor vehicles, power generation and industry," de Gouw said.
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