While wildfires continue to scorch the land on the western side of the United States, smoke has spread far beyond the edges of the blazes.
Areas as far east as New York and Washington, D.C., have witnessed hazy, smothered skies, demonstrating that the health risks associated with air polluted by low-lying wildfire smoke are becoming an increasingly widespread concern.
The Dixie Fire in Northern California is the largest among more than 100 massive blazes burning in more than a dozen states in the West, a region beset by drought and dry weather that have transformed forests and brushland into explosive tinder.
"This is what we're calling the 'new normal,'" said Barbara Weller, a pulmonary pathologist and toxicologist in the research division of the California Air Resources Board (CARB). "The fires, they're going to be longer. They're going to be larger. They're going to be impacting more people."
Climate change is making sure of that with droughts and heat waves. A long history of fire suppression has also accumulated heaps of dead and dried vegetation that fuels larger wildfires.
And now, there are nearly 100 fires burning in the western United States. The Dixie Fire, currently the largest active fire, has burned more than 200,000 hectares and is still only about a third contained. In British Columbia, Canada, another 200 fires are burning.
But fire itself isn't the only danger.
When wildfires burn through natural landscapes and industrial structures, the resulting smoke carries tiny bits of liquid and solid particles from the burned material known as particulate matter. With enough exposure, smoke can cause immediate symptoms such as runny noses, scratchy throats, and watery eyes.
It's the particles on the finer end — 2.5 microns in diameter or smaller — that worry health experts the most, however. Once inhaled, those pollutants are small enough to penetrate deep into the lungs and can even reach the bloodstream. Studies have linked breathing in PM2.5 with health consequences such as lung disease, heart issues and early death.
Although PM2.5 can come from other forms of pollution, such as vehicle exhaust, research suggests that wildfire PM2.5 can be more harmful than non-wildfire PM2.5. Another recent study also linked PM2.5 from wildfire smoke to increased risk of COVID-19 cases and deaths. Given all those outcomes, researchers are only expecting the amount of wildfire PM2.5 to increase in the United States.
"Smoke exposure has become more and more of a concern and it's not just the fact that people are more aware of it," Weller told VOA. "It's just that there is more."
Growing need for protection and awareness
Departments and agencies are urging people to protect themselves as they increase monitoring and encourage practicing awareness of air quality.
"We're getting a lot more calls. You can tell people are really concerned and are definitely trying to figure out what they can do to protect themselves," Amy McPherson, a spokesperson for CARB, said to VOA.
In California, CARB also works on deploying portable air monitors to local air districts and health officers to measure PM2.5 during wildfires, explained Charles Pearson, who supervises the incident and air monitoring section of CARB. The monitors relate the particulate levels to a number on the air quality index, or AQI, which governments can then use to communicate the severity of air pollution to the public.
For smaller communities without their own air monitoring systems in place, that type of information can be critical for knowing when to warn people to stay indoors and minimize their exposure to smoke.
"Because the fires are so long … it's just keeping the monitors serviced, keeping the monitors running, that's kind of been more challenging in the past few years," added Pearson.
The longer and larger fires are causing communities farther away from the West Coast to confront the risks of smoke exposure also.
In early August, Denver's air quality ranked among the worst of major cities in the world, three days in a row, due to smoke from the Dixie Fire. In late July, meteorologists and weather services stations in cities along the East Coast such as New York City, Boston and Washington, D.C., reported smoky skies that appeared to be mostly coming from central Canadian fires.
"[Wildfire smoke] is not regulated by local agencies the same way that we regulate things like traffic or tailpipe emissions," said Sheryl Magzamen, a respiratory epidemiologist at Colorado State University. "Unfortunately, a lot of the protection for protecting our health is really up to us as community members to be aware of air quality alerts and warnings."
Poor air quality can compound other health and economic situations as well. Populations with pre-existing health conditions like asthma, without homes or access to shelters with clean air are especially vulnerable to exposure.
Even during a pandemic, "The health impacts from fires and health impacts from COVID could compound the health risks from both," said Tianjia Liu at Harvard University, who studied the effects of wildfire PM2.5 on last year's COVID-19 cases.
A global hazard
The far-spreading dangers of smoke are not an isolated threat. Human-induced climate change has contributed to a recurring pattern of fierce fire seasons around the world, according to climate experts.
Siberian wildfires have reached a size larger than all other active fires in the world combined. People in Greece and Italy have had to evacuate from the path of more blazes. Turkey's current fire season is the worst in its history.
"This is happening every summer now," said Magzamen, "Now that it's becoming this occurrence year after year, we have to start thinking about what the long-range health implications are."