By Adam Vaughan
During the wildfire season in September 2020, the observatory is in Los Angeles.
Brian van der Brug is a photographer.
The area of the western US hit by the high co-occurrence of two air pollutants because of wildfires has doubled in the past decade.
In the past five years, historic forest fires have claimed lives, destroyed property and forced the abandonment of many homes in California and other western states. There is evidence that the human cost is much higher than the fires are close to.
Daniel Swain and his colleagues at the University of California, Los Angeles were interested in the role wildfires play in the increase in smoke and smog.
There are two types of air pollution that are linked to human health concerns, but they tend to peak at different times of the year. It is possible to see simultaneous peaks in the two pollutants if there is a significant level of wildfire activity in the western US. The health impact of a co-occurrence is thought to be more severe than that of a pollutant alone.
They looked at an area of the western US stretching from Washington in the north to California in the south and as far east as Montana and New Mexico. The area was divided into squares. They looked for extremes in the levels of both ozone and PM 2.5 using data they had previously gathered and new satellite data.
The number of squares that experienced the co-occurrence of the two pollutants more than doubled over the course of 20 years. In hot, dry summers there were many fires in the largest areas. Over a short period of time, it is a very large increase.
The number of people affected increased. 46 million people were exposed to pollutants on one day.
The cumulative harm to millions of people who are exposed repeatedly is very high and it is a public health crisis.
According to the study, an increase in atmospheric ridges of high pressure sitting in place is both driving the start of fires and worsening the impact of air pollution by trapping it.
The research shows how widespread the human health impacts are. Most of the people who are exposed to air pollution are not living in places that are threatened by fire. He says that people who are safe from fires are not safe from air pollution.
Science Advances has a journal reference.
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