The Science of Wildfire Smoke

Short Wave


I. Don't know about you. But when I hear the word smoke, it makes me think of huge thick plumes of different shades of gray sort of blanketing everything nothing too complicated for somebody like Jessica though smoke is an incredibly complex mixture of different gases and particles, and if we look just at the gases, there are hundreds to thousands of different gases that are formed in biomass burning biomass, we're. Talking things like trees and brush that burn up in wildfire when it comes to particles and smoke there's also a huge range from larger ones in the form of ash dust that can work quickly settle out of the sky, but you also get really teeny tiny particles on the order of millions of a meter in diameter and those really small particles can stay in the atmosphere for a lot longer. In from the particulates side, the thing that people seem to be the most freaked out about is this pm two point five or this little the little particles that are super super small, and there seems to be a lot of that going on right now in California and like large parts of the West Right. Yeah. So one of the primary Hazardous Air pollutants is articles that are called pm two point five has a overall diameter of two and a half micrometres. This and that's roughly about fifty times smaller than a single grain of salt. So, really really small particles. The smaller particles not only can they travel further distances, but they also have this unique ability to follow the sort of micro air currents can bend around corners and edges and everything, and that means that if you're breathing in smoke, those larger particles are GonNa hit the back of your throat first, but the smaller particles can actually make it all the way. Down your throat and the deep into your lungs, and that's where they start to cause all kinds of different health effects. One of the most interesting things about smoke is how it behaves how it interacts with the different layers of our atmosphere including the layer closest to us called the boundary layer and how big that layer is how thick it is depends on temperature. So at night when? It's cooler that layer condenses comes back down in altitude also with cooler temps and higher humidity at night wildfires tend to die down and when they die down, that's actually when they produce quite a bit of smoke and not mixing into a more shallow boundary layer just means you get a lot more smoke very close to the ground particularly at night especially if you're in a kind of. Mountain valley where it just starts to pool and accumulate, and it's not really diluted or moved out of your immediate area until the sunrise comes that boundary layer starts expand the wind speeds, pick up and kind of take the smoke away. Sure. Yeah. I guess I didn't I had no idea that you know in areas where there's wildfire burning but the smoke actually kind of settles back. At night and it makes me think about like you know it's night. It's cool. You want to open a window, right? That can be problematic. It is yeah, and that's and that's true of most air pollution sources but particularly. So for smoke many of the Western states even here in Colorado, it's not necessarily all that common that you have air conditioning It does cool down quite a bit at night and so that is the time people will turn on fans. Etc Try to ventilate the house. Get Cool at night a course your home. At night sleeping and breathing off through the night and so again, that's one way that you can be exposed to smoke that you might not necessarily think of. And so I think it's important to remember. Right. So we're looking at areas like California and Colorado were seeing them on fire. We're seeing the smoke in all of this smoke doesn't just hang out there right? Like smoke really travels. Certain smoke plumes can literally travel the world and go to really remote places, and of course, with fires were we're impacted here in the United States right now. But of course that flips as we go to the next season and then the southern hemisphere so fires just a constant emission source across the globe and as I said as it. Gets admitted and the the different layers of the atmospheric and stay in the atmosphere longer, and that just means it can get carried by the wind currents further and further down wind, and so I've been looking at the different fire models and stuff that knows producing and can see that right now even the most of the fires are certainly on the west coast. To. percent or more of the continental US seeing the effects of this smoke. So even you know my family who lives in Ohio can go out and see these red sunsets potentially from smoke that's being emitted out in California and Colorado, and so that smoke can just travel tens to hundreds of miles down wind from the source. Yeah. Yeah Okay. So we have this smoke right and it's all over the West You know how does the smoke leave? Jessica like how long are people in? California people where you live in Colorado going to be living under these like poor air quality conditions and yes I am asking you to predict the future. Well that's what I'm best at so. The do things that will determine when residents particularly of California those most impacted by the smoke we'll get some relief is, of course when the fires go out and with that, you'll need a change in the weather patterns. So some rain to help. Put out those fires and even if the fires are going. Again, shift in the wind pattern can help. Move. Some of that smoke out away from them but all that means is somebody else will get impacted by that smoke. So one of the things I always try to remind folks is that we all live downwind of somebody. So it might be great air-quality where you're at but you know if there's another emission source just behind you gonNA impact your neighbors, and so in that regard California might get some relief but then maybe Idaho or Montana. Now gets inundated with more smoke there. So that's the sort of immediate way that you can reduce your exposure to the smoke. But in the atmosphere and the only way smoke is truly removed as if it's really out of the atmosphere and it's Not. Necessarily destroyed it's just removed from the atmosphere. You know the kicker is though when this smoke maybe clears up from way that we can detect it like just by going out and be like, Oh, I can breathe a little bit. It never just disappears right like you know smoked feeds into this cycle of climate change, right? The primary component is going to be related to those particles and so particles or something that can both. The climate as well as heat the earth, and so that's where that size and color of the particles really comes into play and so the white. Particles that you associate with clouds generally reflect radiation back to space. So that's a cooling effect rate. If you're under a cloud on a super sunny day, you immediately feel better in cooler on when that cloud is overhead. The other ways, the those darker particles, the black soot those are things that are readily absorb radiation from the sun, which means when the sun goes down. They can also re admit that radiation back into our atmosphere, and that's what contributes to that the global warming effect, the greenhouse gas effect the so important for climate change. So that's one way that the aerosols play into it right and all of these things kind of feed into in this is simply put these things feed into a longer hotter fire season. So it's kind of this garbage cycle. Unfortunately. Yeah. We call that a negative feedback cycle. And so. Those particles that are released from biomass burning may of climate and climate continues to change which could lead to more fires and so forth. You just get unfortunately negative feedback. We're just continues down the wrong path rather than trying to correct itself or balance itself out. You know I feel I feel like the wildfires and the smoke are very visual examples of climate change I. Mean Do you think that these fires could impact how people are thinking about climate change and what needs to be done? I. Hope. So I mean there there's many difference. Really visual ways of seeing climate change with our own eyes. I mean from the rising sea levels and daytime flooding that's happening and some of the coastal cities to the amount of runoff that you see on the Greenland ice sheet to these huge you know ice shelves claiming off Antarctica I mean the signs are all around the biometric burning is certainly one that impacts. You know a large community of people out West and as you mentioned, it's a very visceral response and then with climate change, you often hear of global warming and of course, fires represent that heat. And so that's certainly a connection there as well and so. I can only hope that people start to think. About how much their lives will be changed as our climate continues

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