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Air quality index (AQI⁺) and PM2.5 air pollution in Manitoba •
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When outdoor air quality drops, the EPA recommends upgrading to a MERV 13 filter — or the highest-rated filter your HVAC system can handle — to help capture more of the fine particulate (PM2.5) that comes with poor air quality. MERV 13 is the highest rating most residential systems can run without restricting airflow.
AQI stands for Air Quality Index, the EPA's scale for reporting daily air quality. It runs from 0 to 500. The higher the number, the greater the level of air pollution. Values at or below 100 are generally considered satisfactory; values above 100 mean air quality is unhealthy, first for sensitive groups, then for everyone as numbers climb.
The AQI tracks five major pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. The reported AQI value reflects whichever pollutant is highest at that time — most often ozone or fine particles (PM2.5).
Monitoring stations measure pollutant concentrations, and the EPA converts each into a standardized 0–500 score using set breakpoints. Each pollutant gets its own sub-index, and the highest sub-index becomes the reported AQI. That's why a single number can represent different pollutants on different days.
An AQI of 0–50 is rated "Good" — air quality poses little or no risk. 51–100 is "Moderate," acceptable for most people though unusually sensitive individuals may want to limit prolonged outdoor exertion. Anything at or below 100 is generally considered satisfactory air quality.
100 is the dividing line: at or below it, air quality is satisfactory for the general public. From 101–150, air is "Unhealthy for Sensitive Groups" — people with respiratory conditions, older adults, and children. From 151–200, it's "Unhealthy" and everyone may begin to feel effects.
Short-term AQI spikes usually come from wildfire smoke, temperature inversions that trap pollutants near the ground, high-ozone weather (hot, sunny, stagnant days), or heavy traffic and industrial activity. Check a real-time source like the map on this page to see which pollutant is driving today's reading in your area.
Many runners follow the EPA category lines: below 50, no adjustment needed; 51–100, unusually sensitive people may shorten intense workouts; above 100, sensitive groups are advised to reduce prolonged or heavy outdoor exertion; above 150, that advice extends to everyone. Exercise increases how much air you breathe in, which is why thresholds matter more during workouts.
A common rule of thumb is to keep windows open when the AQI is under 100 and close them when it climbs above, especially during wildfire smoke events when fine particles are elevated. When windows are closed, running your HVAC system with a fresh filter helps capture particles circulating indoors.
Public health agencies generally suggest considering a well-fitted N95-style respirator outdoors when the AQI exceeds 150, particularly during smoke events. Cloth and surgical masks don't filter fine particles effectively. Follow guidance from your local health department, which may adjust recommendations during severe episodes.
Ask anyone in Winnipeg about the summer of 2025, and the sky comes up first. Wildfire smoke hung over the city for weeks, turning afternoons hazy and pushing air quality readings to the very top of the scale. Days like that are becoming a normal part of the Manitoba calendar. That’s why this page keeps things simple: a live AQI map you can read at a glance, a plain explanation of the numbers, and a few steps that actually help on a smoky day. We won’t try to scare you, just give you straight answers from people who think about indoor air for a living.
Check the live air quality index (AQI) map for Manitoba below. Find your city, read the number, and in seconds you’ll know whether to open the windows or keep them shut. The map updates every hour, and you can see how today compares with the rest of our national page.
Want today’s air? Use the live map above. Find your city and read the number. It updates every hour.
Is it bad? Good or Low‑risk means clean air. Unhealthy or High‑risk usually points to wildfire smoke, so it’s a day to stay in and filter the air.
AQI or AQHI? Canada uses the AQHI, from 1 to 10+. Most global apps show the AQI, from 0 to 500. On either one, a higher number means to take more care.
Best filter for smoke? An Optimal (MERV 13). Add an Odour Eliminator for the smell.
Easiest fix? Close the windows, run the furnace fan, and change your filter every 60 to 90 days.
There’s an official index for the big centres. Environment and Climate Change Canada publishes the Air Quality Health Index for Winnipeg, Brandon, and Flin Flon. For everywhere in between, the live map above fills in the picture.
Wildfire smoke is the main event. From roughly May through September, smoke from northern Manitoba and neighbouring provinces is the most common reason readings climb.
PM2.5 is the pollutant that matters most. These are the fine particles in smoke, small enough to slip deep into your lungs and exactly what a higher‑rated filter is built to catch.
Winter has its own story. Through the long heating season, cold, still days can trap pollutants close to the ground while your furnace runs for months on end.
The fix is mostly indoors. You can’t change the air outside, but you can change what your furnace pulls through the house.
We make it easy to keep up. Over 600 sizes, including the hard‑to‑find ones, plus free shipping to Canada and Subscribe & Save, so a fresh filter shows up before you’d think to reorder.
The AQI turns a lot of monitoring data into a single number on a colour-coded scale. The lower the number, the cleaner the air. Here's what each band means for your day.
| AQI | Category | What It Means For You |
|---|---|---|
| 0–50 | Good | Air is clean. A great day to open the windows. |
| 51–100 | Moderate | Generally fine. Unusually sensitive people may notice mild effects. |
| 101–150 | Unhealthy for Sensitive Groups | Sensitive groups should take it a little easier outdoors. |
| 151–200 | Unhealthy | Everyone may feel some effect, so limit long stretches of exertion outside. |
| 201–300 | Very Unhealthy | Reduce outdoor activity and keep the windows closed. |
| 301+ | Hazardous | Stay indoors where you can and lean on good filtration. |
A quick word on the colours. Green and yellow are everyday air. Orange is the point where sensitive groups, including children, older adults, and people with asthma or heart conditions, should start paying attention. Red and above is when it's worth keeping everyone indoors and letting a good filter do the quiet work.
If you've compared two apps and seen two different numbers, this is why. Canada has its own measure. Environment and Climate Change Canada publishes the Air Quality Health Index, or AQHI, on a scale of 1 to 10+, built around the combined health risk from several pollutants at once. Most global maps, including the one on this page, show the AQI on a 0-to-500 scale, which is what most people look up. Neither is wrong. There are two ways of describing the same air, and we show the AQI here because it's the more familiar number. For the official AQHI, see the resources below.
| AQI (U.S. Style) | AQHI (Canada) | |
|---|---|---|
| Scale | 0–500 | 1–10+ (Low, Moderate, High, Very High Risk) |
| Based On | The single worst pollutant | Combined health risk from PM2.5, ozone and NO₂ |
| Reported By | Many global apps and maps | Environment and Climate Change Canada (Winnipeg, Brandon, Flin Flon) |
| You'll See It | On most international maps | On official Canadian forecasts |
It depends on where you are and what the wind is doing. The fastest answer is the live map above. Find your city and read the number. In the Good or Low‑risk range, the air is clean, and you can carry on as usual. When readings climb into the Unhealthy or High‑risk range, the cause is almost always wildfire smoke in summer, or a winter inversion trapping pollutants on a cold, still day. If your area is running high, the simplest move is to keep the windows shut and let a clean filter do its job.
A few things shape what you breathe across the province.
Wildfire smoke. The big one, roughly May through September. Smoke from fires in northern Manitoba and neighbouring Saskatchewan can lift fine‑particle levels quickly, often hundreds of kilometres from the flames. The 2025 season showed how fast it moves, pushing readings in Winnipeg to the top of the scale on the worst days.
Fine particulate matter (PM2.5). The microscopic particles that air quality indices watch most closely because they travel deep into the lungs. For the full picture, read our plain‑language guide to PM2.5.
Winter inversions. On cold, still Prairie days, a layer of warm air can settle over cold air near the ground and trap pollutants there until the wind picks up. That happens through the months your furnace runs hardest.
Spring pollen and field dust. Seasonal allergens and agricultural dust can nudge readings up in spring and around harvest.
When a specific fire is making the news, our shows where the smoke is heading.
Every summer runs the same way. The day a smoke advisory hits a region of Manitoba, our orders from there jump, because people feel the air change before they ever check a number. What I tell my own neighbours is simple. You can’t control the smoke outside, but you can control what your furnace pulls through the house. On a hazy day, a clean Optimal (MERV 13) does more for a closed-up home than almost anything else, and most people are running a filter a step or two too low. Check the map, then check the date on your filter. Do both, and the air inside stays clean.
— Indoor Air Quality Specialist, Filterbuy
We make air filters, not monitoring stations. So when you want live numbers, the smoke forecast, or solid health advice, we point you straight to the folks who do each best. Think of this as the short list a good neighbour would jot down for you. Everyone is free and reliable, and each is good for a particular moment. Bookmark the ones that fit how you live, and you’ll always know where to look.
Environment and Climate Change Canada keeps the official Air Quality Health Index for Winnipeg, Brandon, and Flin Flon, updated throughout the day with a forecast for what’s coming. If the map above gives you the quick read, this is the number we’d trust to confirm it.
Source: weather.gc.ca/airquality/pages/provincial_summary/mb_e.html
This is Environment and Climate Change Canada’s running list of air quality warnings and special statements for Manitoba. A glance tells you whether it’s an ordinary day or one to keep the windows shut and let your filter do the quiet work.
Source: weather.gc.ca/provincialsummary_table
Wildfire smoke is the usual reason Manitoba’s air turns, and FireSmoke Canada forecasts where it’s headed over the next couple of days. It’s a handy way to plan, like deciding whether to move the ball game indoors, instead of being caught off guard.
Source: firesmoke.ca/forecasts/current/
When you can smell smoke but aren’t sure where it’s coming from, the Manitoba Wildfire Service has the answer: active fires, any local fire bans, and daily updates, all on one map. It’s the quickest way to connect today’s haze to what’s happening across the province.
Source: gov.mb.ca/wildfire/
Health Canada lays out, without any fuss, what to watch for, who should take extra care, and the small things that make a real difference indoors and out. Think of it as the calm, practical “what now?” that pairs with the numbers on the map.
Source: canada.ca/en/services/health/healthy-living/environment/air-quality/wildfire-smoke.html
The World Air Quality Index runs an independent, non‑commercial map with readings from individual stations, including live PM2.5. It’s a helpful second opinion when you want to see how your own neighbourhood compares with the official figure.
Source: aqicn.org/map/canada/
If you’d like to understand the figure behind the colour, this plain explainer covers how the AQI is worked out and what each band means for your day. There’s no jargon and no pressure, just the background for whenever you want it.
| What It Tells Us | Source | |
|---|---|---|
| 317 | Wildfires recorded in Manitoba by mid-July 2025, well above the roughly 231 average for that point in the season. Smoke-affected air days have become a routine part of the Prairie summer. | CBC News (Manitoba Wildfire Service) |
| ~15,300 | Premature deaths in Canada each year that Health Canada links to air pollution. A reminder that the air we breathe, indoors and out, matters over the long run, not only on smoky days. | Health Canada |
| 10+ | The top of the AQHI scale, the “very high risk” band. Much of Manitoba, including Winnipeg, hit it during the July 2025 smoke events. | Environment and Climate Change Canada / CBC News |
Here’s our honest read. Smoke season isn’t a freak event anymore. It’s a regular feature of the Prairie summer now, and worth planning for the same way you plan for winter. When the air turns, most people go looking for a standalone purifier. That’s a fair instinct, but it skips over the system already moving air through your whole house: your furnace. It runs for six to eight months of the year regardless, and the filter inside it is either doing real work or barely any, depending on what you’ve put in.
We’d rather you spend a little thought on that filter than a lot of money on a gadget. A well‑chosen pleated filter, changed on schedule, quietly cleans the air you spend your time in. We’ll be candid about the limits, too. A furnace filter isn’t a respirator, and it won’t clear the smoke outside. But for the air inside, where Manitobans spend most of the heating season, and most of any smoky week, it’s one of the few things actually in your control. The playbook is short: cleaner filter, fan running, windows closed when the AQI is high.
Whatever the map says right now, here’s what’s worth doing.
If the AQI is 0 to 50 (Good). Open the windows and air the place out. Check when you last changed your furnace filter. If the air’s calm, it’s a good moment to set up Subscribe & Save so you’re never caught short.
If the AQI is 51 to 100 (Moderate). Carry on as normal, but check in on anyone with asthma or allergies. If you’re due for a filter change, today’s a fine day to do it.
If the AQI is 101 to 150 (Unhealthy for Sensitive Groups). Close the windows. Switch your HVAC to the fan setting so air keeps cycling through the filter. Keep outdoor time shorter for children, older adults, and anyone with a respiratory condition. If your filter looks grey, replace it now.
If the AQI is above 150. Stay indoors with windows and doors closed and the fan running continuously. Lean on an Optimal (MERV 13) or Odour Eliminator filter. Check on neighbours who might need a hand. And if anyone has chest tightness, a lingering cough or shortness of breath, contact a healthcare provider or call Health Links–Info Santé at 204‑788‑8200 or 1‑888‑315‑9257.
It varies by region, so check the live map above for your city. Readings in the Good or Low‑risk range mean clean air, while higher numbers usually point to wildfire smoke. When readings are high, keeping the windows shut and running a good furnace filter helps.
An AQI of 0 to 50 (Good) is clean for everyone. From 51 to 100 (Moderate) the air is generally fine, though unusually sensitive people may notice mild effects. Above 100, sensitive groups should start taking more care outdoors.
AQI is a 0‑to‑500 scale used by many global apps, based on the single worst pollutant. AQHI is Canada’s official 1‑to‑10+ scale, published by Environment and Climate Change Canada for Winnipeg, Brandon, and Flin Flon, and it reflects the combined health risk from several pollutants. Both rise as air quality worsens.
PM2.5 means fine particles smaller than 2.5 microns, small enough to travel deep into the lungs. It’s the main driver of poor readings during wildfire smoke, which is Manitoba’s most common cause of bad air, and it’s exactly what higher‑rated filters are built to capture.
The most common cause is wildfire smoke, especially from May through September, drifting in from fires in northern Manitoba and neighbouring provinces. Winter inversions on cold, still days and spring pollen can also raise readings. The day’s specific driver is usually noted in Environment and Climate Change Canada’s air quality forecast.
An Optimal (MERV 13) filter captures the fine smoke particles that standard filters miss, and an Odour Eliminator filter helps with the smell. Change filters more often during the smoke season so they keep working effectively.
We generally suggest every 60 to 90 days, but during active wildfire smoke, check more often. Every 30 days is reasonable, and visible discolouration is a clear sign it’s time to swap. Manitoba furnaces run six to eight months a year, so a subscription timed to the heating season keeps you ahead of replacements.
Clean air shouldn’t depend on the weather. Whatever today’s reading says, the right filter keeps your home’s air fresh through smoke season, allergy season, and the long Manitoba winter when the windows stay shut. We stock over 600 sizes, including the hard‑to‑find ones, with free shipping to Canada and Subscribe & Save so you never run out. Not sure which to choose? Superior (MERV 11) handles everyday allergens, Optimal (MERV 13) is the one we recommend for wildfire smoke, and Odour Eliminator clears that lingering smell.
