On July 20, a curious haze enveloped the sky over the eastern half of the United States. The sunsets appeared redder than usual, the atmosphere seemed gray and dense, and the air quality deteriorated dramatically. People from Washington, DC, Pittsburgh and New York have photographed abnormal shades – only to find out that wildfires nearly 3,000 miles away are the cause.
When large fires are smoldering in the western United States, smoke can spread throughout the country, covering large populated areas. Recent research suggests that smoke from both western wildfires and local sources can be more harmful to residents of the eastern United States than many think.
For much of the past decade, researchers have found that about three quarters of all smoking-related emergency room visits and smoking-related deaths occurred east of the Rocky Mountains due to higher population densities. Hospital admissions for asthma were highest between April and August.
“Smoke is not only a problem for the West. We think there may be a lack of awareness in the East because you are not in the immediate vicinity of these large wildfires and they do not affect your daily life, ”said Caitlin O’Dell, lead author of the study and postdoctoral researcher at George Washington University.
Fires release a mixture of pollutants that, if inhaled, adversely affect human health. Researchers examined the effects of PM2.5 pollutant or particulate matter less than 2.5 microns in diameter. These tiny particles can enter the lungs and aggravate or lead to numerous health problems, from respiratory ailments to heart disease.
“We have conducted decades of research and have shown that air pollution damages our bodies. I think we should be concerned about inhaling wildfire smoke and its effect on our overall health, including cardiopulmonary adverse health effects, ”said Erin Landgut, who studies the effects of wildfire smoke on respiratory health at the University of Montana and did not take participation in the study. study.
The dangers of smoke from wildfires are relatively well understood in the West, where the sky is regularly hazy during the fire season. Landgut’s study found smoke from wildfires in Montana could increase the incidence of influenza in a few months in the state. Another recent study found that fine particulate matter in smoke from wildfires is associated with an increase in COVID-19 cases in California and the states of Washington.
As fire seasons have become more frequent in the West in recent decades, the eastern half of the country is also increasingly feeling the consequences.
On July 20, major cities including Washington, Baltimore, Boston and New York were hit by huge billowing plumes across the country. New York City had the worst air quality in 14 years.
“We predict that smoke or smoke fires will be the dominant source of these [PM2.5] particles in the United States by the end of the 21st century, ”O’Dell said. “We have an increasing threat to air quality and health from wildfires and smoke, and so we wanted to try to understand and quantify the health burden that smoke poses to the United States.”
O’Dell and colleagues at Colorado State University analyzed smoke and health data from 2006 to 2018. They used observations from satellites and ground-based instruments to obtain daily local PM2.5 estimates as well as track the location of smoke in the atmosphere. Using existing data on asthma emergency department visits, they compared the number of people who went to the hospital for asthma on smoky days versus smoke-free days.
The team found that in the West, where the concentration of smoke and particulate matter is higher as they are closer to fires, there is a higher percentage of emergency room visits for asthma on smoky days. In some years, smoking-related visits accounted for more than 1 percent of annual asthma visits.
In the East, the percentage of smoking-related annual hospital visits for asthma was lower, at about 0.3 to 0.6 percent. However, due to larger settlements in the East, the total number of smoking-related asthma hospital visits was higher, although the concentration of smoke particles was lower on average.
The exceptions were 2017 and 2018, when most cases of smoke-related asthma occurred in the West, as fires affected some of its major cities. Forecasts indicate that bushfire seasons like 2018, the deadliest and most destructive on record in California, may be more frequent in the future.
The health effects of prolonged exposure to smoke were also stronger in the East. The team found that about 6,300 additional deaths occur each year, with the majority occurring in the most populous states. Less than a third – about 1,700 – of deaths occurred in the West.
“It’s not surprising at all,” said Rodney Weber, an atmospheric chemist at the Georgia Institute of Technology who was not involved in the study. “A lot of smoke dissipates where it is difficult to detect.”
Weber said that people generally only notice smoke pollution in the East when the sky is foggy or the sun is red, but smoke particles can remain in the background at lower levels and pose a hazard.
Weber also noted that smoke from forest fires can carry potentially harmful organic molecules that can affect health. Research shows that organic molecules become more toxic as they become trapped in the air and age. Molecules oxidize and dissolve more easily in the human body, including the lungs.
“This smoke can be much more insidious because it can eventually spread over much larger areas. [and] expose large populations to a sufficiently toxic source, and this can last for quite some time, ”Weber said.
O’Dell and her colleagues studied several hazardous air pollutants in smoke in their study, but the team said further research with additional species is needed for a better understanding.
In general, researchers agreed that people should pay more attention to the EPA and local government air quality index and take personal measures to protect themselves from smoke pollutants, such as wearing N95 masks and strengthening air filtration systems.
“We need to start thinking about what we breathe inside our homes, not just outside, which means we need to start thinking about air quality filters – all this public awareness of our air quality,” Landgut said. “Maybe some of this research will just help gradually add to this conversation.”