The moment a wildfire starts near you, you'll get an instant alert and simple tips to reduce your smoke exposure.
30xSmaller than a human hair
Fine enough to reach deep into the lungs. A MERV 13 is built to capture it.
It Doesn't Stay Local
Smoke rides the wind far downwind — you can get smoky air with no fire nearby.
Simple steps to reduce indoor exposure.
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.
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.
Use the live wildfire smoke tracker and upgrade your air filters today to protect your lungs and your home.
Shop Filters For Smoke Protection
Author: Michelle Wan (see About the Author below for linked bio)
Reviewer: David Clark, Licensed HVAC Technician
Publish Date: July 22, 2026
Updated Date: July 22, 2026
Step outside in Indianapolis today, and the sky looks a little wrong. A pale gray-white veil sits behind the sun, with no smell and no fire on any local map. IDEM has called an Air Quality Action Day for Marion County for ground-level ozone, while smoke from Canadian wildfires drifts high above the state. The live map above tracks both layers, and this page covers what today means for your HVAC filter.
Indianapolis is under an IDEM Air Quality Action Day today for ground-level ozone, with air expected to reach the Unhealthy for Sensitive Groups range this afternoon. Canadian wildfire smoke is also drifting high above the region, dulling the sky without necessarily raising ground-level PM2.5. Check the live map for your AQI, keep windows closed and your HVAC on recirculate during peak heat, and run a MERV 13 filter if your system can handle it.
Today is Indianapolis's second Knozone Action Day of 2026, part of a statewide alert covering more than 40 counties.
Canadian wildfire smoke is riding high in the atmosphere today and is not the main driver of the ground-level concern.
Ozone forms locally on hot, still afternoons, while smoke travels in from fires far away, and each calls for a different response.
A MERV 13 filter captures particulate matter from both events but does not remove ozone gas.
Limiting outdoor exertion during Action Day afternoons and running your HVAC on recirculate are the two highest-impact steps today.
Ozone peaks between 2 and 6 p.m. and can shift with wind, so recheck the map later.
Two alerts are active over Central Indiana today. The first is IDEM's Air Quality Action Day for ozone, covering Marion County and the broader region. High heat, sunshine, light winds, and stagnant air are the classic recipe, and IDEM expects levels to reach the Unhealthy for Sensitive Groups range this afternoon.
The second is the haze itself. Canadian wildfire smoke has moved into the upper atmosphere, visible as a milky, diffused sky. The Indianapolis NWS office says this layer is riding high enough that it should not worsen surface air quality, though it can tamp down temperatures and produce a vivid sunset. This is Indianapolis's second Knozone Action Day of 2026, following June 4, part of a statewide alert reaching more than 40 counties.
An ozone Action Day calls for cutting outdoor exertion in the heat. A smoke event calls for sealing the house and running your HVAC on recirculate. Today's map shows which is driving conditions in your ZIP code. See Filterbuy's live Indianapolis AQI map and guide for more.
Source: U.S. EPA Air Quality Index categories, applied to today's IDEM Air Quality Action Day for Central Indiana.
Open the live map and enter your Indianapolis ZIP code or allow your location. Flame icons mark active wildfires, rarely seen near Marion County. The shaded plume overlay shows where smoke is moving, the layer most relevant to today's Canadian smoke.
Click the dot closest to your neighborhood for the current AQI reading and note its timestamp. Use the time slider to see how conditions may change through the day, and cross-check anything unusual against IDEM SmogWatch or the NWS hazards page. See Filterbuy's guide on how to read a wildfire smoke map for a fuller walkthrough.
Indianapolis rarely burns on its own. Marion County is densely built, humid, and short on the dry fuel that drives large wildfires out West or across Canada's boreal forest, so a fire icon here is almost always a small brush fire.
Ground-level ozone is homegrown, forming when vehicle exhaust and other emissions react with sunlight and heat on a still, sunny, 80-degree-plus afternoon. IDEM tracks this from March through October and calls an Action Day at or above 70 parts per billion.
Wildfire smoke arrives differently, drifting down from Manitoba, Saskatchewan, and Ontario at the edge of the boreal belt producing North America's largest fires. A high-pressure ridge over the Great Lakes can bend the jet stream south, carrying smoke over Indiana within a day or two, often before any ground-level change. See Filterbuy's guide to Canadian wildfire smoke.
The map is the most reliable answer, but these checks offer a first read while you reach for your phone.
Wildfire smoke almost always carries a campfire smell, even before it visibly settles. Ground-level ozone has no smell, so an odorless haze points to ozone.
Smoke gives the sky a flatter, grayish or tan cast, and on heavier days the sun dims to a soft orange disc. Ozone haze looks brighter and whiter, sun still glaring, since ozone is invisible.
Ground-level ozone builds through the day, worst between 2 and 6 p.m., then fades at night. Smoke does not follow the sun and can thicken at any hour, even sitting over Marion County at sunrise.
If two checks disagree, or anyone in your household is in a sensitive group, trust the map.
The map shows what is happening outside. What you do about it happens inside, and the two alert types call for different responses.
On an ozone Action Day, limit hard outdoor exertion, especially for kids, older adults, and anyone with asthma, between 2 and 6 p.m. Refuel your car after dusk and postpone gas-powered lawn equipment until evening. A standard HVAC filter cannot remove ozone gas, so reducing exposure means limiting outdoor exertion, not upgrading your filter.
During a smoke event, close windows and doors, set your HVAC to recirculate, and run the highest MERV-rated filter your system can handle without straining airflow. A MERV 13 filter is the general recommendation for wildfire smoke's fine PM2.5 particles. Keep the fan on "on" rather than "auto," check your filter more often during a multi-day stretch, and see Filterbuy's 7-step guide to keeping wildfire smoke out of your house for the full checklist.
Outdoor crews and trail users should shift heavy effort to the morning before ozone peaks. Rideshare and delivery drivers logging hours behind the wheel should keep cabin air on recirculate. None of this replaces the protection a clean filter gives at home.
Indianapolis families often assume a hazy sky means a wildfire problem, when just as often it is a homegrown ozone Action Day. After manufacturing filters for over a decade and serving more than two million households, we have learned that the households who fare best during either event are the ones who check the map first and match their response to what it actually shows, not just to what the sky looks like.
David Heacock, Founder and CEO, Filterbuy
The national map combining fire locations, smoke plumes, and AQI data.
Source: AirNow Fire and Smoke Map
The federal overview of how EPA tracks wildfire smoke and the AQI.
Source: EPA: Wildland Fires and Smoke
Federal guidance on reducing smoke exposure and risk groups.
Source: CDC Safety Guidelines: Wildfires and Wildfire Smoke
The state page on how Indiana calls an Action Day.
Source: IDEM Air Quality Action Day (AQAD) Advisories
The city program declaring Knozone Action Days.
Source: Indianapolis Office of Sustainability (Knozone)
The local NWS real-time hazards page for the metro.
Source: National Weather Service Indianapolis: Current Hazards for Central Indiana
Guidance on protecting your lungs during a smoke event.
Source: American Lung Association: Wildfire Smoke and Lung Health
Wildfire PM2.5 carries a measurably higher respiratory hospitalization risk than PM2.5 from other sources, per a California analysis.
Source: Aguilera et al., 2021, Nature Communications (PMC7935892)
By early August 2025, over 6.6 million hectares had burned across Canada, exceeding the 25-year average.
Source: NASA Earth Observatory, Widespread Smoke from Canadian Fires
NOAA satellites tracked thick smoke plumes over the eastern U-S on June 2, 2025, filling gaps left by ground monitors in areas like Central Indiana.
Source: NOAA NESDIS, Wildfire Smoke and Air Quality
Blaming a hazy sky on wildfire is understandable, but today shows why the map matters more than the mood outside. Bookmark this page and treat your HVAC filter as part of your response plan.
Canadian wildfire smoke is drifting high in the atmosphere over Central Indiana today rather than settling at ground level. Today's main concern is a separate ozone Action Day. Check the live map for your ZIP code.
An advisory IDEM issues when ozone or particulate matter is forecast to reach unhealthy levels, calling for reduced outdoor exertion.
No. It captures fine particulate matter, including wildfire smoke PM2.5, but cannot remove ozone gas. Reducing ozone exposure means limiting outdoor exertion, not filter upgrades.
Marion County sits downwind of Canada's boreal forest. A high-pressure ridge over the Great Lakes can bend the jet stream south, carrying smoke to Central Indiana within a day or two.
IDEM tracks ozone from March through October and calls Action Days when hot, stagnant conditions threaten the Unhealthy for Sensitive Groups range, usually in July and August.
Stay indoors with windows closed, run your HVAC on recirculate with a MERV 13 filter, and follow your action plan. Seek emergency care for severe shortness of breath or chest pain.
AirNow's Fire and Smoke Map, IDEM's SmogWatch site, and the city's Knozone program publish current readings, linked in the Essential Resources section above.
Today is the second, following June 4, part of a statewide alert covering more than 40 counties.
Smoke usually carries a campfire smell and can dim the sun to orange, while ozone has no smell and peaks between 2 and 6 p.m. When the cues disagree, trust the live map.
Ready before the next Action Day or smoke event reaches Indianapolis? Shop Filterbuy MERV 13 Air Filters sized for your system today.
Air Quality Action Day (AQAD): An IDEM advisory issued when ozone or particulate matter is forecast to reach unhealthy levels.
Air Quality Index (AQI): The EPA's color-coded 0-500 pollution scale.
PM2.5: Fine particulate matter 2.5 micrometers or smaller, small enough to penetrate deep into the lungs.
Ground-Level Ozone: A gas formed when emissions react with sunlight and heat, distinct from the protective ozone layer above.
MERV Rating: A 1 to 20 scale measuring filter efficiency. MERV 13 is the general floor for smoke events.
Boreal Forest: Canada's cold-climate conifer forest, prone to large, long-burning wildfires.
Knozone: Indianapolis's ozone-season advisory program for Marion County.
Michelle Wan is Filterbuy's Brand Manager and Air Quality Writer. This page was technically reviewed by David Clark, Licensed HVAC Technician.
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