Longueuil, QC Live Wildfire Smoke Map
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The moment a wildfire starts near you, you'll get an instant alert and simple tips to reduce your smoke exposure.
What's In The Smoke
30xSmaller than a human hair
Fine enough to reach deep into the lungs. A MERV 13 is built to capture it.
How Far It Travels
It Doesn't Stay Local
Smoke rides the wind far downwind — you can get smoky air with no fire nearby.
What To Do During A Smoke Event
Simple steps to reduce indoor exposure.
- Stay In, Close UpShut windows and doors to keep smoke out.
- Set Fan To "On"Keeps air cycling through your filter, not just when heating or cooling.
- Recirculate AirSwitch off fresh-air intake so you're not pulling smoke in.
- Run A MERV 13Built to capture the fine PM2.5 in smoke.
- Add A PurifierExtra filtration for the room you use most.
- Wear an N95 if OutsideFits snug to block fine particles — a cloth mask won't.
The Best Air Filter For Wildfire Smoke
During smoke events, the EPA recommends upgrading to a MERV 13 filter — or the highest-rated filter your system can handle — to help reduce the fine particles smoke brings indoors. MERV 13 is the level most home HVAC systems can run while still capturing PM2.5, the fine particulate that makes up the bulk of wildfire smoke.
- Captures PM2.5 particles
- Blocks ash, soot, and smoke odor
- Keeps your indoor air safe—even when the outdoor air is dangerous
- Meets the EPA's recommended rating for filtering fine wildfire smoke particles.
Wildfire Smoke FAQs
Facts About Wildfires
Over 70,000 wildfires burn in the U.S. every year.
Wildfire smoke can travel 1,000+ miles, affecting states that aren't even near the blaze.
Exposure to wildfire smoke can worsen asthma, trigger heart issues, and lead to ER visits.
Indoor air can hold more fine particles during wildfire events unless it's properly filtered.
The EPA advises using MERV 13 filters or portable HEPA air cleaners during wildfire smoke events.
Don't Wait Until The Smoke's Inside.
Use the live wildfire smoke tracker and upgrade your air filters today to protect your lungs and your home.
Shop Filters For Smoke Protection
Live Longueuil, QC Forest Wildfire & Smoke Map Today: Local Air Quality Tracking & Indoor Protection Solutions
The live map above shows where forest fires are burning across Québec and the rest of Canada today, and which way their smoke is drifting toward Longueuil and the South Shore. To see how much of that smoke is reaching street level, pair it with Environment Canada's Air Quality Health Index (AQHI) forecast for Montréal, just across the St. Lawrence, and Québec's Air Quality Index (IQA). Both scores describe the air outside. Inside, your protection comes down to your furnace filter or, in a baseboard-heated home, a portable air purifier.
We're Filterbuy. We make air filters, not forecasts, and we've been cutting them in our own U.S. factories since 2013. So we'll point you to the official fire and smoke sources and spend our time on what we know from the factory floor: the air inside your home.
TL;DR
Longueuil, on Montréal's South Shore, rarely has a forest fire nearby, yet it regularly breathes smoke from boreal fires hundreds of kilometres away. Check the live map, then the Montréal AQHI and the IQA, and follow official advisories first. In Filterbuy's experience, homes cope best when filtration is ready before the haze arrives: MERV 13 in the furnace with the fan on, plus HEPA air cleaners in the rooms you use, or HEPA units alone in homes without ducts.
Key Takeaways
Longueuil residents can follow Environment Canada's Montréal AQHI forecast, and Québec's IQA map has a Longueuil station.
Health Canada recommends HVAC filters rated MERV 13 or higher to capture the fine particles (PM2.5) in wildfire smoke.
58% of Québec households heat with electric baseboards, so many rely on a HEPA air cleaner instead of a furnace filter.
A box fan with a 20 × 20 in. MERV 13 filter is an EPA-tested stopgap when no purifier is on hand.
During an Environment Canada smog warning, the Ville de Longueuil bans outdoor wood fires and indoor wood-burning fireplaces.
How to Read the Live Longueuil Wildfire and Smoke Map
Fire icons come from the Canadian Wildland Fire Information System (CWFIS), Natural Resources Canada's fire tracker, and grey shading shows satellite-detected smoke. That smoke can stay high overhead, so Filterbuy treats the map as the first of three checks:
Find the fires. SOPFEU's active fire map lists each fire in Québec's protection zone and its status.
Follow the plume. Environment Canada's FireWork smoke forecast shows where smoke is heading over the next 72 hours.
Confirm at ground level. Look up the Montréal AQHI forecast or the Longueuil station on Québec's IQA map. When the ground monitors and the map disagree, trust the monitors.
Longueuil's Two Air Quality Scores: AQHI vs. IQA
Both scores pick up wildfire smoke, but they report it differently.
What the AQHI numbers mean for your household:
Filterbuy's action line: when the AQHI reaches 7, the IQA reads "poor," or the AirNow map shows a U.S. AQI of 100 or more, put MERV 13 in your HVAC, set the thermostat fan to "On," run a HEPA air cleaner in each occupied room (bedrooms first), and close the house up. That threshold is Filterbuy's recommendation. Outdoors, Environment Canada says N95 masks can reduce exposure to fine particles.
The IQA's forest fire layer switches off September 30, but smoke doesn't. In 2025, nearly 70% of Québec's forest fires broke out between August and October, mostly in the drought-hit south, according to SOPFEU's season review. Fire icons thin out too, since CWFIS hot-spot mapping generally runs May to September; in October, rely on the AQHI and FireWork.
Where Longueuil's Wildfire Smoke Comes From
Longueuil sits across the St. Lawrence from Montréal, so smoke over Greater Montréal usually reaches the South Shore the same day. Smoke can start anywhere in Canada, as Filterbuy's live Ontario wildfire and smoke map and live Canada wildfire and smoke map show, and it reaches Longueuil often:
2023: On June 5, the Direction de santé publique de la Montérégie warned of an incoming plume from northern Québec fires. On June 25, smog warnings covered Montréal, Québec City, Laval, Longueuil, and Trois-Rivières, and Montréal's AQHI climbed to 10+.
2026: Environment Canada issued a Montréal-area air quality warning on July 18, and by early August about 1.2 million hectares had burned across Québec, per SOPFEU figures in Canada's National Observer.
How Do You Reduce Wildfire Smoke Inside Your Longueuil Home?
Follow Environment Canada alerts and Montérégie public health advice first; if they say stay in or leave, do that.
A furnace filter does nothing for a home without a furnace, and in Québec that's a lot of homes. Statistics Canada reports that 58% of Québec households heat with electric baseboards, so this plan starts with your type of home.
According to the EPA, indoor PM2.5 still sits around 55% to 60% of outdoor levels with windows shut and no air cleaner running, and near 100% in leakier homes. A filter or air cleaner is how you bring that down:
During the June 2023 plume, Montérégie public health went further, advising residents to turn off the air exchanger.
If your home is ducted, MERV 13 is the tier to use for smoke. The EPA notes that most furnaces and HVAC systems can take a MERV 13 filter without equipment problems when it's replaced often, so the only check is a size match. Filterbuy's best MERV filter for wildfire smoke guide covers the rest. As Michelle Wan puts it:
I don't want anyone to feel like they need an HVAC license just to pick the right filter.
Michelle Wan, Brand Manager and Air Quality Writer, Filterbuy
Smoke loads a filter far faster than everyday dust. During a smoke event, the EPA advises checking it often and replacing it when it looks dirty (dark brown or black), which can be well before the usual interval, so keep a spare on hand. David Clark, who reviewed this page, sees what happens when that slips:
Most systems I test are not struggling because the filter is too efficient. They are struggling because it has been in there since spring.
David Clark, Licensed HVAC Technician, Filterbuy HVAC Solutions
If you rely on air cleaners, size them to the room. Health Canada's portable air cleaner guide recommends a tobacco-smoke CADR of at least two-thirds of the room's square footage, so a 12 × 12 ft bedroom (144 sq ft) needs at least 96. Sized well, portable air cleaners have cut indoor PM2.5 by an average of 57% during smoke events, according to the NCCEH. Skip ionizers and ozone generators; the EPA advises choosing a cleaner that makes little or no ozone.
No air cleaner yet? Build one tonight. Strap a Filterbuy 20x20x1 MERV 13 filter to the back of a 20 × 20 in. box fan. EPA research found the design effective and recommends a UL- or ETL-certified fan from 2012 or newer. Filterbuy's rule: never leave it running unattended. It's a stopgap until you can get a certified air cleaner; our Corsi-Rosenthal box guide shows a stronger build.
Whatever your setup, keep windows and doors closed, limit exhaust fans, which Health Canada notes can pull in outside air, and skip candles, frying, and vacuuming while smoke is in. Pleated filters catch particles, while smoke odours are gases; if a smell lingers, try an Odour Eliminator (carbon) filter.
Longueuil Details Most Smoke Guides Miss
A smog warning means no wood fires, by city rule. Whenever Environment Canada issues a smog warning, the Ville de Longueuil bans outdoor wood fires and indoor solid-fuel fireplaces until it lifts. Gas, propane, and ethanol fireplaces are still allowed.
Filter sizes are in inches, even in Canada. Sizing is the question Filterbuy's customer service team answers most: order by the size printed on your old frame, not a centimetre measurement, and for unusual sizes, we cut custom air filters to order.
Hot and smoky at once? Don't tough it out. Health Canada's cleaner-air guidance aims to keep indoor temperatures below 26 °C. If yours can't with the windows closed, head somewhere cool and filtered, like a library.
When Is the Air Safe Again in Longueuil?
Once the Montréal AQHI drops back to low or moderate and the IQA reads "good" or "acceptable," check FireWork for new plumes, then air out the house and reset your air exchanger.
Filterbuy's take: swap your smoke-season filter before the heat comes on. Late-season smoke in Longueuil runs into heating season, so a summer filter may start winter already loaded. Our five-second check: if it looks dark brown or black, replace it.
Supporting Statistics
17% more asthma emergency visits. As smoke from Canada's 2023 fires drifted south, U.S. asthma-related emergency visits ran 17% above expected across 19 smoke days. (Centers for Disease Control and Prevention, MMWR, August 2023)
120 counties failing for short-term particle pollution. The 2026 "State of the Air" report gave 120 U.S. counties in 23 states failing grades for short-term particle pollution, and wildfire smoke remains a major driver. (American Lung Association, State of the Air 2026)
About 50% less indoor PM2.5. Upgrading to a high-efficiency HVAC filter may cut indoor PM2.5 by about 50% when the fan runs continuously, which is why Filterbuy pairs MERV 13 with the fan set to "On." (U.S. Environmental Protection Agency, Strategies to Reduce Exposure Indoors)
Next Steps
Save Longueuil in a free SOPFEU alert profile.
Set up Filterbuy's Subscribe & Save.
Frequently Asked Questions
Where Can I See a Live Wildfire Map for Longueuil Today?
Start with the live map at the top of this page, then check SOPFEU's fire map for each Québec fire's status.
How Often Should I Change My Furnace Filter During Wildfire Smoke?
Check it during a smoke event and replace it when it looks dark brown or black, often well before the normal interval.
Glossary
AQHI (Air Quality Health Index): Canada's federal 1-to-10+ health-risk scale.
AQI (Air Quality Index): The U.S. 0-to-500 scale shown on the AirNow map.
IQA (Indice de la qualité de l'air): Québec's provincial air quality index.
PM2.5: Particles 2.5 micrometres or smaller, the main health risk in smoke. See what PM2.5 is.
MERV (Minimum Efficiency Reporting Value): A 1-to-16 filter efficiency rating. See how MERV ratings work.
HEPA: High-efficiency particulate air filtration.
CADR (Clean Air Delivery Rate): A purifier's rated output of filtered air; use the smoke CADR.
Filterbuy: A family-owned U.S. filter maker (since 2013) selling in Canada through Filterbuy.ca.
SOPFEU: Société de protection des forêts contre le feu, Québec's forest fire protection agency.
CWFIS: Natural Resources Canada's wildland fire mapping system.
FireWork: Environment Canada's 72-hour wildfire smoke forecast.
Montérégie: Longueuil's region.
HRV / ERV (VRC): Heat or energy recovery ventilator, called a VRC or air exchanger in Québec.
Smog warning (avertissement de smog): An Environment Canada alert for expected poor air quality.
About the Author and Reviewer
Michelle Wan is Filterbuy's Brand Manager and Air Quality Writer. She works with Filterbuy's U.S. manufacturing team to turn filter data into practical advice. David Clark, a Licensed HVAC Technician whose Filterbuy HVAC Solutions crews take residential service calls year-round, reviewed this page for technical accuracy.
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