Looking Back at Smoke from the Rice Ridge Fire

Simply put, 2017 was the worst wildfire smoke season we have seen in Missoula County. Of course, anyone who lived in Seeley Lake during the Rice Ridge Fire already knew that. It's not uncommon for a community near an active fire to see heavy smoke, especially during periods of rapid fire growth. The smoke in Seeley Lake, however, continued to return and build, night after night, even on days that didn't see dramatic fire activity.

The proximity of the Rice Ridge Fire and the valley's topography led to the extraordinary smoke buildup. Mountain valleys are prone to nightly temperature inversions that trap pollution near the valley floor. Every night, cold air flows downhill and settles into valleys.

This summer provided an extreme example of how nightly temperature inversions can result in high pollution levels in a community. After the sun set and temperatures cooled, smoke from the Rice Ridge Fire followed the Morrell Creek drainage into Seeley Lake and became trapped in the inversion layer. As the wildfire season dragged on, nights became longer and colder and inversions grew stronger. These already strong inversions were compounded by thick smoke that limited the sun's ability to warm the ground and break the inversion.

The pollutant we're most concerned about in wildfire smoke is PM2.5 – particulate matter that is 2.5 microns in diameter and smaller. The particulate is so tiny that it can enter your bloodstream when you breathe it in. Once inhaled, it sets off an inflammatory response that can lead to cardiovascular and respiratory complications. And, PM2.5 is a cumulative pollutant: The more you're in it, the worse it is for you. The National Ambient Air Quality Standard for fine particulate matter averaged over 24 hours is 35 micrograms in a cubic meter of air (µg/m3). The Environmental Protection Agency considers anything over 250 µg/m3 to be hazardous to human health.

The wildfire smoke season in Seeley Lake lasted 50 days (July 31 – September 18). On 44 of those days, the smoke reached levels that we know are harmful to human health. In 35 days the smoke met (and exceeded) hazardous conditions.

The smoke in Seeley Lake first hit hazardous conditions Aug. 1. The 1-hour PM2.5 concentrations started building overnight and peaked at 892 µg/m3 at noon. On Aug. 3, the morning 1-hour PM2.5 concentrations were up around 1,000 µg/m3. On Aug. 4, the morning 1-hour PM2.5 concentrations exceeded 1,000 µg/m3. By Tuesday, Aug. 8, Seeley Lake had already seen six August mornings with hazardous air quality.

When Seeley Lake started seeing repeated hazardous conditions, it became clear that the stock health advisory messages were no longer sufficient - they were not designed for this type of long-duration smoke event. The classic hazardous air quality health message encourages everyone to limit physical activity, stay indoors and follow their physician's advice. This type of "hunker down and wait for the smoke to pass" message is inadequate when the smoke is inside buildings and will be present for the forseeable future. It was time for the Missoula City-County Health Department (MCCHD) to move beyond issuing health advisories and take a more active role in wildfire smoke response.

The only way to truly escape the smoke's impacts would be to escape the smoke all together. So Aug. 9, MCCHD issued an official recommendation that residents leave the area or at least avoid spending nights in the smoke. The statement included recommendations for canceling athletic events and practices and creating clean indoor air spaces using HEPA air filters, as well as a discouragement against relying on masks.

MCCHD also began working with partners to create clean air spaces in Seeley Lake.

When the Rice Ridge smoke hit Seeley Lake, Climate Smart Missoula provided 30 filters to MCCHD for distribution to vulnerable Seeley Lake residents. The nonprofit had launched a pilot project this summer to provide HEPA room air filters to Missoula residents but saw the greater need in Seeley Lake. The Partnership Health Center in Seeley Lake directly distributed most of the donated filters to their patients. A few filters were distributed to individuals by MCCHD staff.

When it became clear that the smoke would still be present when school started, the MCCHD reached out to the Seeley Lake Elementary School with the goal of creating safe spaces for students. We calculated that 40 room air filters would be necessary to remove smoke from the classrooms (this would place two filters in each classroom). Using the manufacturer discount secured by Climate Smart Missoula, SLE and MCCHD each purchased 20 filters.

When the high school re-opened after the worst of the smoke was past, MCCHD purchased 10 more filters to help remove lingering smoke from the school.

When we realized no one had researched how smoke like what we were seeing in Seeley Lake would translate into health outcomes, MCCHD reached out to the School of Public Health and Community Health Sciences at the University of Montana to see if anyone in the department would be interested in launching a health study. A group of researchers quickly came together to design a study that incorporates basic health measures and multiple questionnaires. The study launched Sept. 20. Community interest was high, and the initial cohort includes 95 residents that the researchers hope to follow up with to check for long-term health effects from the smoke. The group is currently working on preliminary data analysis and is applying for grants to help them expand the study and pursue follow-up visits.

This was a difficult wildfire smoke season and we are still absorbing the scope of its effects. One thing we do know is if you can't leave a smoky area, creating a clean air space is the best way to protect your health. We encourage everyone living in Seeley Lake and Missoula County to prepare for wildfire smoke (and there will be future wildfire smoke seasons) by using a HEPA filtration unit to create a clean space in their homes.