Wildfires have long filled western Montana valleys with smoke. However, the frequency and intensity of wildfire smoke impacts have been increasing since the year 2000.
With this fall’s extended wildfire season, several people have asked the Missoula City-County Health Department Air Quality Division “How does this year compare to previous wildfire seasons and is this the worse smoke season ever?”
These questions can be tricky because the two methods for measuring a smoke season, namely the duration of the wildfire season and number of high smoke days, can give different answers.
While 2000 was a relatively short wild fire season (lasting only 20 days from August 3rd to the 23rd), a 24-hour particulate reading of 219 µg/m3 on Aug. 3, 2000, still sets the record for the single worst wildfire smoke day in Missoula. Some of the single hour particulate levels in 2000 were greater than 500 µg/m3. This year, the highest particulate day in Missoula has been 108 µg/m3, and our highest single-hour measurement was 205 µg/m3.
As in 2000, the Bitterroot Valley has been hit by the wildfire smoke much more intensely than Missoula. The longest wildfire smoke season was 2007, when smoke events started on July 16 and ended around September 12. This year’s smoke season has gone further into the fall than ever before and may end up as our longest wildfire smoke season ever if hard frost or rains do not come soon.
Based on the smoke levels we have had to this point, most healthy adults should not have long term health effects from the wildfire smoke. The most common short term reactions to the smoke include headaches, shortness of breath, a tight chest feeling, and an increased chance of colds.
As the smoke season continues, people unaffected at the start of the season can start to feel these short term symptoms and may want to modify their behavior based on how they are reacting to the smoke. Individuals should use common sense and awareness of their personal reactions to the smoke to guide their activity levels.
Sensitive groups, which include children, asthmatics, the elderly, and people with cardio-pulmonary diseases, should start reducing their activity levels and exposure to smoke when air quality becomes Unhealthy for Sensitive Groups. For a complete guide to smoke recommendations, consult the current Missoula County air quality web page.
When air quality becomes unhealthy, non-sensitive people should pay attention to how they are reacting to the smoke and moderate their activity levels appropriately.
One the most effective strategies to reduce smoke exposure is to stay indoors, especially if the building in questions has a particulate air filtration system. A home-size HEPA (fine particulate) filter or electrostatic precipitator can help reduce smoke levels in a room at home. Stay away from any devices that produce ozone since ozone is itself an air pollutant.
If you can’t leave the smoked-in area, another strategy to limit exposure is to reduce activity levels. Increased activity levels correspond to increased exposure because when exercising you are likely to start breathing more heavily through your mouth. This means you’re bypassing the natural defense mechanisms in your nasal passages and delivering smoke straight to your lungs.
While reducing the activity levels of small children can be a bit tricky, it is still a good idea!
From the 2008 revision of Wildfire Smoke: A Guide for Public Health Officials:
“In general, wearing a mask is not a highly effective exposure reduction strategy during a smoke event. In order for a mask to provide protection, it must be able to filter very small particles (around 0.3 to 0.1 micrometer) and it must fit well, providing an airtight seal around the wearer’s mouth and nose. Commonly available paper dust masks, which are designed to filter out larger particles, such as sawdust created by sanding, typically offer little protection. The same is true for bandanas (wet or dry) and tissues held over the mouth and nose. Surgical masks that trap smaller particles are also available, but these masks are designed to filter air coming out of the wearer’s mouth, and do not provide a good seal to prevent inhalation of small particles or combustion gases. As a result, these tend to be no better than dust masks. In fact, masks may actually be detrimental, giving the wearers a false sense of security, which may encourage increased physical activity and time spent outdoors, resulting in increased exposures.”
Ben has worked at the Missoula City-County Health Department as an Air Quality Specialist since 1991. He is the city staff liaison for Local Governments for Sustainability and helped write Missoula’s Greenhouse Gas Energy Conservation Plan. His responsibilities include designing and implementing air pollution studies, maintaining and operating an air pollution monitoring network, calling air quality alerts and advisories, subdivision review, Hazardous Material Response Team member, and running Missoula County’s industry compliance and permitting program.