2020 was one of the worst years for PM 2.5, as three record-breaking fires raged in the state and air quality alerts for the particulate matter were triggered on more than 110 days in Denver, Boulder and Weld counties.
“There's no question our patients notice it,” said Dr. Anthony Gerber, a pulmonologist at National Jewish Health in Denver.
Air alerts in recent years have prevented people with chronic health issues, like emphysema and bronchitis, from getting outdoors for regular exercise – something Gerber normally recommends to improve the health and lifespan of his patients.
“It’s a real double whammy,” Gerber said. “You take that away for four to six weeks in the summer and they might really lose ground.”
About a quarter of the federal Air Quality Index reports from sensors around Colorado in the last decade were Yellow, Orange, or Red – categories where outdoor air can start to harm sensitive people, like Gerber’s patients, all the way up to being unhealthy for all people.
A big contributor to days that were reported as worse than Green (or “satisfactory”) is ground-level ozone, a chemical reaction triggered by sunlight and heat linked to vehicle exhaust and industry. Though the state has failed to meet federal standards for the pollutant, data analyzed by KUNC shows ozone levels declining slightly.
Yet in the last five years, PM 2.5 levels have gone up significantly in Colorado as large wildfires have raged in the state and throughout the West. That includes California, where eight of the 10 largest wildfires in state history struck in the past three years. An investigation by NPR member stations in California and Stanford University’s Environmental Change and Human Outcomes Lab found that smoke from the blazes travels across the country, including into Colorado, a problem that has worsened in the last decade, with the number of days Americans are exposed to PM 2.5 rising dramatically.
Two Colorado State University researchers – Sheryl Magzamen, an associate professor of epidemiology, and Jeffrey Pierce, a professor of science – have studied the emerging trend for years, including evidence that wildfire smoke makes people sick.
“What we found is that smoke events increased risk of hospitalizations, especially for respiratory diseases like asthma, but for cardiovascular diseases as well,” Magzamen said. “We also found that increases in smoke are also associated with increases in asthma deaths and cardiac arrest deaths along the Front Range.”
PM 2.5 is super small – it stands for particles that measure 2.5 micrometers or less.
“It’s probably about one hundredth of the width of human hair,” Pierce said.
That means it can bypass the body’s defenses and travel into the lungs, not only interfering with breathing, but potentially getting into the bloodstream, leading to a host of health problems.
“PM 2.5 has been associated with low birth weight, especially from wildfires — there's a really interesting study that showed that,” Magzamen said. “Neurological disease, diabetes and end-stage renal failure, so the systemic effect of PM 2.5 is really scary.”
CSU researchers and doctors interviewed by KUNC say more studies are needed to understand the specific long-term health effects associated with wildfire smoke. Still, it is not just people with preexisting health issues that doctors worry about.
“The people who live close to these fires and people who are being exposed to this smoke more frequently may have some long-term health issues that we just don’t know yet,” said Dr. Jesse Johar, the Emergency Department medical director and chief of staff at Banner McKee Medical Center in Loveland. “So we're advising everybody to try to protect yourself and take whatever precautions you can if you have to be out on a smoky day.”
Johar said people should be careful about when they go outside and where they go if the air quality isn’t good, but they shouldn’t give up on going outside and getting the health benefits of exercise. Apps and websites with air quality alerts can help pinpoint the best places and times to exercise, he added.
“When there’s a particularly smoky day, you might check the area and say, ‘Hey, you know what, it's smoky here but actually in Greeley, it's not as bad today,’” he said.
KUNC found a lot of variability on a county level in the AQI data. Weld County, for instance, had 136 PM 2.5 days in 2019 and 129 in 2020. While also contending with a similarly high number of PM 2.5 days as Weld County, neighboring Boulder County had fewer days overall.
On hazy days, Jack Todd often asks himself whether it is safe to ride his bicycle to work in Denver and to run errands.
“It is tough. I ride every day and there are days that I question whether that's the smartest thing for me to do,” Todd said. “I choose to because I don’t want to make it worse. I don’t want to make the air quality worse by driving.”
Todd is director of communication and policy for Bicycle Colorado, an organization that advocates for bike riders statewide.
“We have been working for almost 30 years now to get more people on bikes and there are so many reasons for that,” he said. “It's better for our physical health, it's better for our mental health and it's better for our cities and our environment.”
He said sometimes he may work at home, wear a mask or ride slower so that he doesn’t breathe too heavily.
The pollution his organization is combating is contributing to climate change. In Colorado and throughout the West, models predict an increasing number of hotter and drier days, which can lead to more wildfires.
“It doesn't happen every year,” Pierce, the CSU researcher, said. “But then, of course, last year and this year have been really bad and, on average, it's increasing and I would suspect that when you average things over each decade, we will probably continue to see it get worse.”
PM 2.5 can be in the air even if you don’t smell or see smoke. Pierce and Magzamen found something counterintuitive in their research related to that. Hospitalizations in Colorado went up at an unexpected time – not when people were near the blazes, but rather when fires burned far away.
“One of our hypotheses is that that strong emergency response to the local fires actually kept people safe from the smoke as well, either through evacuation or sheltering in place,” Magzamen said. “There was also a massive amount of media coverage about the local fires.”
The reason people might have been safer during local wildfires is that when officials evacuated them or told them to shelter, they avoided going outside and being directly exposed to the worst air. But when fires are happening far away, there are fewer warnings, though the level of PM 2.5 in the air remains dangerous. A takeaway from the researchers’ finding is that people might not know to take precautions when they should be and that consulting air alert reports and apps even when there’s a slight haze in the distance could be important.
KUNC asked Colorado Department of Public Environment officials about the rise in PM 2.5 levels. The department acknowledged an increase in climate-caused wildfire activity across the state and the West, but noted that PM 2.5 levels have not violated federal standards. They state also pointed to expected reductions in other sources of PM 2.5 — such as emissions from coal plants — saying it has “secured closure dates for numerous” coal-fired units around the state.
