Wildfire Smoke and Health

In the third installment of the FairAir talk series Emily Fischer from Colorado State University, explains how smoke and the health impacts from wildfire smoke specifically are studied in her talk, “Wildfire Smoke and Health”.

Missed the talk? You can view the recording HERE.

Q&A Session:

Q: Is wildfire smoke similar to wood smoke from burning wood to heat homes?

Emily Fischer: Let me take that a little bit broader. When you have a wildfire, for example, you’re burning everything, the leaves, the soil.  You can also think of as many different little fires all at the same time, so a mega wildfire will have a flaming front, smoldering sections, and then if it has a big updraft, a lot of that smoke is getting all sucked in. So the major components of smoke are the same, or largely the same, in wildfire smoke and camp fire smoke.  The ratios of them will sometimes change and you’ll have slight changes, based on the fuel that you’re burning.  There are some nuances there but there’s a lot of different ways that you can burn something. You can have something that’s flaming, you can have something smoldering, you can have what’s called pyrolysis.  There’s a lot of different processes happening so every fire is different and every fuel type is different, but this sort of basics that I said in the beginning, fine particulate matter, carbon monoxide,  carbon dioxide, thousands of different BOC,  those are in your wood smoke and they’re in the wildfire smoke.


Question: Which mask is best to protect against these particular gases that are linked with health issues

Emily Fischer:  The gases would not, in general, be filtered out by your N95. But what I would like to say about some of the gases.  The hazardous air pollutants, you have to think about a little bit differently than the fine particulate matter. There’s a few different things happening.  One, the air pollutants that are coming in the smoke are often adding on to the anthropogenic air pollutants that are already there. Two, many of the hazardous air pollutants, we think about that health exposure over a long durations and often this wildfire smoke is a relatively short exposure. Three, when you think about the hazardous air pollutants and we think about those absolute magnitudes on an average year, or when averaged out over let’s say a decade, the health impacts are very small for those hazardous air pollutants. We didn’t really know that until one of our recent studies. However, an extreme year, like in 2018 and 2020, those kinds of years, then your hazardous air pollutant concentrations will exceed health risk thresholds. For an extreme year like 2018, there are regions where this hazard index would be sufficient to cause other health effects, but those are rare.  The point here is that we need to understand, these extreme years might become more frequent under a warmer world.  While I could say in the past, the gas faze pollutants probably haven’t been an issue, I think moving forward, we might want to think about monitoring formaldehyde, for example in some of these fire prone areas.


Question:  How close do you have to be to a fire to have that hazardous air pollution issue.

Emily Fischer: It’s more the duration. You can have extremely high concentrations, for example forest firefighters are exposed to this. You can’t extrapolate from what forest firefighters experience to the general public and expect the health effects to be the same. Firefighters are typically in there 20s or 30s, super healthy, super fit. To figure out the health effects of a pollutant you have to look at the large population, a large exposure over, a long time period. If smoke is in the area for a few days, you usually don’t see them crossing any of these EPA thresholds.  But what we don’t know, is what is the impact of repeated long exposures is.


Question: What are the cumulative effect of the exposures? In Fairbanks we are exposed to high levels of admissions relating to PM 2.5 and precursor gases in wintertime, and then frequently have bad fire years.

Emily Fischer: I don’t, but I want to explain one of the reasons why. In some of these studies that our team has worked on collaboratively on these things,  I will tell my epidemiologist friend that I think smoke came to this area of Oregon and I think it hit these sites at this concentration, from this day, to this day, maybe this two week period.  What they do with this information is they use what’s called a case crossover design to look at changes in the health outcomes for that period.  They take a look at what happened to that population, for example, the Wednesday before the smoke, and the Wednesday after the smoke hit. The look at the same season to make sure other variables are the same like amount of pollen, the same work days, etc. The only thing that we’re assuming changed is that the smoke came on the middle Wednesday. Then you can see if there were increases and hospital admissions or ER visits, as we compare the smoke impacted Wednesday to the non-smoke impacted Wednesday the week before and the week after.  So if you have these really long durations, it’s harder to find your clean Wednesdays and you end up comparing to outside the seasons.

The other thing that you have that makes it really hard to identify the health effects is behavioral changes. For example in Colorado when we have our very local fires it’s in the news, people are hyper aware of what’s happening, it’s in the media all the time, and we think people change behavior.  Whereas if we get age smoke from California, people are not as in tune to what’s happening even if we may have a consistently high fine particulate concentration. That’s another thing that’s making it really hard to figure out exactly what the health impacts are because people will also be switching their behavior for different kinds of events. Those are some nuances for why answering this question is a little bit tricky.


Questions: What are ways to reduce impacts of wildfire smoke during difficult wildfire season?

Emily Fischer: This can be unpacked in a lot of different ways.  One important response relates to addressing climate change. Though I am not a forest manager, I would say another response relates to forest management and things like exploring the use of controlled burns during the off season, although this isn’t an option when you are already in a bad fire year. Also consider personal controls like installing home air filters or an air condition unit if there is a long duration of smoke. This personal control isn’t possible for everyone, so it’s also important to think about building safe community air spaces like in a library or school. A lot of impact reduction will have nothing to do with fires which requires advanced training for people on how best to respond to local air quality events.


Question: What are the best masks to use if N95s are no longer available and what is the effectiveness of COCID face coverings in blocking particles?

Emily Fischer: Probably your cloth masks don’t do much. The more material you force particles to go through the harder it is. I think there probably are masks that will be better than nothing.  For example masks with really good nose fit, really good fit around the face, have a filter inside them, or have multiple layers. But fine particulate matter is very, very, very small and can get all the way down into your lungs.  Any little crack that it can get around, like a poorly fitting mask or filtration that’s not as good as the N95s, you are going to continue to get exposed to the fine particulate matter.


Question: Is the frequency or intensity of Western US wildfires changing?

Emily Fischer: Intensity is kind of a hard word to unpack, but what I can say is that the burn area has been increasing, particularly since the 1980s. That increase is somewhere on the order of 20 more additional large fires per decade according to papers published by Anthony Westerling.  Though that number may have increased since these papers were published.


Question: A follow up question to that is if this increase is driven by climate change?

Emily Fischer: Sure, there’s definitely a link between the climate change and wildfires. There is a lot of year to year variability.  Not every ecosystem is as affected by variation in temperatures, but some do. In the Rockies, your largest burn areas occur during summers that are hot and dry.  What we know is that climate change is causing increased temperatures and therefore an increase in what we call vapor pressure deficit or the thirstiness of the atmosphere.  During our recent bad fire year, not everyone event can be blamed on climate change, but the duration of the fire season was longer. We had extreme growth in the fires, and we had a very large drought and very warm temperatures so there are many other factors that played into the wildfire season we had. The history of land management in an area is also really important especially if there has been a lot of fire suppression.  Ignitions are another factor, especially human ignitions. Climate is one piece of the puzzle that makes for longer and more severe fire seasons.