Wildfire Smoke

Smoke from the Cliff Creek Fire settles into the Trail Creek drainage along Highway 22 west of Teton Pass last summer. Heavy smoke from wildfires in Idaho, Montana, Washington and British Columbia has settled in the valley.

It’s another smoky August in Jackson Hole.

But it’s actually what you can’t see — smaller, invisible particles of air contaminants — that worries Devra Davis.

Davis, an environmental health scientist and writer who is co-founder and president of the Environmental Health Trust, is concerned that there is a public health threat that no one knows about.

“Don’t be deluded into thinking that if you don’t see it, it’s safe,” Davis said. “Because invisible air pollution is just that: invisible.”

Davis is the author of more than 190 publications in books and journals and was the senior advisor to the assistant secretary for health in the Department of Health and Human Services, as well as an appointee to the Chemical Safety and Hazard Investigation Board under President Bill Clinton.

There are two kinds of pollution: visible and invisible. Visible pollution includes the smoke we see obscuring the mountains and cloaking the valley in a hazy glow.

“Everyone can see it and smell it,” Davis said. “But invisible pollution is smaller than visible pollution. And it’s so small that when you breathe it in it can go through the membranes of your lungs into the bloodstream. The smaller the particle, the more harmful it is.”

PM 2.5, an air pollutant called fine particulate matter, is smaller than the width of a human hair and can be suspended in the air for weeks. It stays suspended because it is lighter than air, and it is harmful to humans because nose hairs don’t block it the way they do larger particles.

“Any time you burn organic matter you get PM 2.5,” Davis said. “Whether that be cigarettes or marijuana or woodsmoke or engine exhaust.”

Several large wildfires are actively burning in Idaho and western Montana. The News&Guide reported Aug. 7 on a large wildfire in the Bridger-Teton National Forest, about 25 miles northwest of Kemmerer.

Side effects of too much PM 2.5 absorption, such as increased risk for strokes and heart attacks, aren’t an immediate worry in Jackson.

“These levels are not killing anyone immediately,” Davis said. “It’s not the perfect storm yet.”

But if you’re in what is considered a higher-risk category — young, elderly or asthmatic, for example — you might want to adjust your physical exertion level accordingly.

That includes exercising outside in the morning, or not at all, if you’re considered to be at risk.

Rachael Wheeler, Teton County Public Health’s response coordinator, advised people to keep their windows closed, not burn candles, which can add to the particulate matter in the air, and avoid extreme exercise or even vacuuming, which can stir up particles.

Teton County Public Health doesn’t have equipment to measure fine particulate matter. Wheeler said it’s hard to say “exactly what [pollution] we have and the quantity because we don’t have those exact numbers.”

Wheeler said visibility is often a good indicator of rough air quality. Anything other than that from other areas, she said, is “a little more speculative.”

During the Cliff Creek Fire close to town last summer, Wheeler said that the U.S. Forest Service brought in an air quality monitoring machine to augment local capabilities, or lack thereof.

“In Mexico City they have better air monitoring than we do,” Davis said.

Davis said she and her colleagues have considered purchasing a machine for Public Health to use.

The closest air quality monitoring station to Jackson that monitors PM 2.5 is in West Yellowstone, Montana.

The national ambient air quality standard is 35 or fewer micrograms per cubic meter of air, or µg/m3. In West Yellowstone, where the air monitoring station is maintained by the Montana Department of Environmental Quality, levels reached 42.3 µg/m3 Monday afternoon, which pushes into the “unhealthy for sensitive groups” category.

Afternoon peaks

A Wyoming Department of Environmental Quality station in Pinedale had a 24-hour rolling average of 22 µg/m3, but Davis cautioned against just looking at averages over long periods of time as a metric for judging air quality. The longer the amount of time data is averaged over, the smaller the average becomes.

“You might also have had peaks,” Davis said. “That is the problem. What are the peaks? The daily average might look fine, but the daily average isn’t the most important thing.”

PM 2.5 measurements tend to “peak when it’s warmest,” Davis said, which is usually late afternoon in Jackson.

A closer station that monitors air quality is the Grand Teton National Park station, which is at Teton Science Schools’ campus in Kelly. However, it only monitors ground-level ozone, or O3, which is a product of several pollutants, such as sulfates, nitrates and other things that form bonds with oxygen.

“Rarely does that get high in our area,” Davis said. The one-hour and eight-hour averages Tuesday were in the “good range,” between 0 and 55 parts per billion.

Inversions keep things hazy

Why do the smoke and the invisible particles stick around?

The same inversion layer that sometimes makes the tops of mountains warmer than the valley floor in the winter plays a role.

Normally hot air rises. A temperature inversion makes it so that warm air sits on top and caps the cooler air. When the air cools at night, it gets trapped in the valleys and can’t escape.

“The mountains capture the smoke,” Davis said. “A strong inversion can make life pretty uncomfortable here.”

Wind and rain, projected in the forecast for this week, should help — at least temporarily. On Tuesday afternoon, it was still unknown what impact the day’s rain showers would have on the air quality.

“The good news is that we live in the mountains,” Davis said. “And as we know, the weather will change. Until then a little precaution is in order.”

Contact Kylie Mohr at 732-7079, schools@jhnewsandguide.com or @JHNGschools.

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