How to stay safe from wildfire smoke, according to our experts | Canada Voices

On July 30, Globe reporter Jesse Winter and emergency physician Dr. Shazma Mithani answered reader questions on this year’s wildfire season, how firefighters and governments across Canada are fighting the fires and how to reduce the health effects of smoke.

Readers asked how wildfires start, the effects of wildfire smoke and how to stay safe in this season. Here are some highlights from the Q&A.

Wildfire season in Canada

What is considered “wildfire season” in Canada, and when does it end?

Jesse Winter: Wildfire season used to be the hottest months in June, July and August. Out west, there’s a long history of early fire risk in May, especially east of the Rockies, when snow has melted but there hasn’t been enough rain to “green up” the forests yet. Thanks to climate change, we’re seeing wildfire seasons stretch longer and longer due to more frequent stretches of heat and drought. It’s now pretty common for fires to start in March and continue to October. In Alberta this year, there was a wildfire in late January on the eastern slopes of the southern Rockies. In the U.S., wildfire is now essentially a year-round risk. I don’t think it will be long before the same is true In Canada.

How do wildfires start?

Winter: They start one of two ways: they’re either triggered by lightning strikes (as we saw in Northwestern Ontario earlier this month), or by human activity (which can be anything from escaped campfires, to flicked cigarettes, to sparks from an ATV exhaust). One thing to note: while climate change does not cause wildfires, it does change the conditions under which they burn, making them larger and more intense. Experts also say that climate change makes lightning storms more frequent, which increases the chances of lightning-caused fires.

Health effects of wildfire smoke

How damaging is wildfire smoke inhalation to humans? Is there any safe amount of wildfire smoke inhalation?

Dr. Shazma Mithani: Wildfire smoke is substantially damaging, and current evidence suggests no safe threshold of exposure. Smoke exposure can have acute and long-term effects on the lungs, brain and heart. During poor air quality from wildfire smoke, I most commonly see patients in the ER with underlying lung issues (like asthma or COPD) come in with flare ups of their disease. I also see otherwise healthy people without lung issues coming in with breathing concerns, headaches, burning eyes and burning throat. Less commonly, I see people come in with chest pain and heart issues during to smoke.

How poor air quality can affect your health, and how to protect yourself

Are Canadian wildland firefighters at a higher risk of cancer and other health effects due to smoke exposure?

Mithani: There is good global and Canadian data to show that both woodland and urban firefighters have an increased risk of lung cancer as well as chronic heart and lung disease. This is due to the chronic wildfire exposure that contains both particulate matter as well as volatile gases that are known carcinogens.

Winter: The research Shazma mentions is vital, and is changing the safety culture within wildland firefighting. Even a few years ago, the prevailing belief among wildland crews was that if it’s “only” organic forest material burning, the smoke wasn’t a significant risk. But the rates of cancer and respiratory issues among often very young firefighters is becoming really worrying. Unlike structural firefighters, wildland crews can’t wear a self-contained breathing apparatus, because those systems require dedicated air bottles that are heavy, and only last around 30 minutes.

Wildland crews work for days at a time in remote places where they simply can’t refill the bottles. There’s research underway in British Columbia to find respiratory protection that firefighters can actually wear for the duration of 12-16 hour shifts, but it is a struggle.

What’s the best air purifier to help filter out wildfire smoke particles?

Mithani: Staying indoors with an air filter is the safest thing you can do during poor air quality. Portable filters should be HEPA, or if you have HVAC or central air, they should have a MERV13 or higher filter.

Do masks help with wildfire smoke, and if so, what’s the best one?

Mithani: N95 respirators with a good fit are best to protect against wildfire smoke if you have to be outside. Fit is the most important, but because they only filter particles and not gases, they shouldn’t be solely relied upon.

How wildfire smoke spreads

How does wildfire smoke move, and how long does it usually affect one particular area?

Winter: How smoke moves is driven by two things: fire behaviour, and wind. A low-severity fire produces less smoke and less heat, which means the smoke generally stays closer to the ground. High severity fires create far more smoke, and also create huge updrafts of rising hot air, which can pull smoke and ash into the sky along with it. Sometimes that process is so intense it causes what’s called a pyrocumulus cloud or — in even more extreme scenarios — a pyrocumulonimbus storm (a fire-driven thunderstorm capable of creating its own weather and lightning). These are the largest and most intense fires possible, and their rising heat column drives smoke and ash kilometres into the sky. From there, it depends on the prevailing winds.

When that much smoke and ash are lofted into the jet stream, it can spread the smoke thousands of kilometres away, including as far as Europe. How long it takes to dissipate from a particular area also depends largely on the wind and weather conditions. There have been huge fires burning only a couple hundred kilometres from Vancouver this summer, but we’ve seen hardly any smoke in this city because prevailing winds keep pushing it farther east.

Controlling wildfires

What methods are usually used to control wildfires, and how effective are they?

Winter: Wildfires are usually controlled by containing them, not fully extinguishing them. When a wildfire first starts, an “initial attack” team of firefighters will respond and attempt to contain the fire to ideally less than a hectare (about the size of a CFL football field). They do this by digging ‘fire guard’ around the fire – scraping a meter-wide swath free of twigs, sticks, leaves, moss, etc. down to un-burnable mineral soil. They’re often backed up by helicopter support to drop buckets of water and cool the fire down, or air tankers dropping water or red fire retardant. That’s often enough to stop a low-severity ground fire. Then they’ll set up pumps and hoses, and attempt to drown the edges of the fire to further reinforce the guard and stop the spread.

The B.C. Wildfire Service’s initial attack success rate is really high – around 85 per cent. If “initial attack” fails, firefighters will bring in more crews, and use heavy equipment to bulldoze wider fire guards around the perimeter, again backed up by aircraft. At this point they’ll often use what are called “planned ignitions.”

Planned ignitions are a tactic to burn sections of the forest on purpose under favourable conditions, to consume as much of the forest “fuel” (leaves, twigs, branches, bushes, trees, etc) so that it doesn’t burn under unfavourable ones. The classic example is a fire burning towards a community, with a road in between. If the winds are pushing the fire away from the community and the road, it might make sense to light the section along the road on fire while the winds are in your favour, so that when they eventually swing back around, the fire will run into a stretch of burned forest before the road, and have nothing to feed on.

All these strategies are pretty effective under normal fire conditions, but climate change has supercharged the fire behaviour that’s now possible. When fires explode under extreme temperatures, low humidity and wind, they are essentially “unsuppressable” — no amount of firefighting or water bombers will stop them until those conditions and the weather improves.

If I live in an area at threat of wildfires, is there anything I can do to protect my home?

Winter: Yes, there is lots you can do, starting with some simple things that are actually pretty easy to do. FireSmart Canada is a great resource so I’d start there. If you have a lawn, make sure the grass is cut low. Removing the lower branches of trees around your property (called “limbing”) really helps keep a fire from reaching into the tree crowns. If a fire is nearby, making sure roof vents and windows are sealed (or can be sealed quickly). Even removing patio furniture, doormats, potted plants from your deck, and making sure firewood isn’t stacked against the house, can help.

It sounds so simple that some people assume it can’t work, but cleaning out dead leaves and needles from your rain gutters is super effective. When a house burns in a wildfire, it’s usually not from a wall of flame or radiant heat, it’s from embers that land on something flammable on the property and start a new spot fire. Removing as many of those potential fuels as possible can give your house a way better chance of surviving even if a fire comes through.

Battling the blazes

How much do governments actually have an impact on how we fight wildfires? Would more funding help our firefighters be more effective?

Winter: Wildland firefighting is a provincial responsibility. Ottawa does not direct actual firefighting beyond, but can help provide some resources, like deploying the military when asked or – as they’ve done this year – procuring more water bombers. Generally firefighting across Canada is coordinated with resources shared between provinces – the idea that provinces experiencing slow seasons can offer firefighters for those with big seasons. This underlying assumption is being strained on a nearly annual basis now, with big seasons impacting multiple provinces at once.

More funding for firefighters would likely help bolster fire suppression, but most experts agree it’s not possible to suppress our way out of this problem. Instead experts point to the need for more preventative work to address the forest fuels build-up on landscapes around communities, better hazard mapping to daylight the underlying forest risks, and better evacuation planning to help reduce the trauma and stress when communities inevitably have to flee.

As we face one of our worst wildfire seasons on record, is it time for Canada to consider a FEMA-style national firefighting force?

Winter: The need for a Canadian version of FEMA is a very live debate right now. We’re one of the only G7 countries without a stand-alone agency like that. A recent Senate committee report recommended creating a national fire office to better coordinate firefighting across the country, and having more federal disaster assistance would likely help. However, there likely is no national firefighting force big enough to simply put out all these fires.

Thanks in large part to climate change, the worst fires, with the worst human outcomes, are frequently burning with an intensity that makes them “beyond resources,” which means there’s nothing firefighters can do until conditions change and fire behaviour slows down. No amount of water bombers can put those fires out when they’re burning like that. Experts are essentially split: some say we do need a national firefighting force despite these challenges, and others say it would be far more cost effective to put that money towards prevention and mitigation.