Air Quality in Indianapolis, Indiana — Live
Live readings from PurpleAir sensors across Indianapolis — with free alerts the moment smoke drifts in.
AQI 43 from 5 PurpleAir sensors · Trending down · data from PurpleAir
As of , the air quality in Indianapolis, Indiana is AQI 43 — Good and falling — with PM2.5 at 7.7 µg/m³, the median of 5 live PurpleAir sensors reading 2 to 65. Canairy's verdict: Breathe easy.
For scale, that PM2.5 reading is below the World Health Organization's 24-hour guideline of 15 µg/m³. The WHO figure is a daily average and this is a live reading, so read it as a sense of magnitude rather than a formal exceedance — a brief spike and a bad day are not the same thing. More on the WHO guidelines
Pollen today in Indianapolis: weeds pollen is the strongest of the three at a low level, from Google's pollen forecast. Canairy shows the tree, grass and weed forecast beside the air reading on every plan, including the free one.
Free to download · Live data from PurpleAir & public monitors
Live PurpleAir sensor map for Indianapolis and Carmel, Fishers, Greenwood, Lawrence. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Indianapolis
The sensors Canairy reads in Indianapolis are 63 AQI points apart right now, from Good to Moderate, which is the whole reason one city-wide number can mislead you: the median describes air you may not be standing in.
| From city center | AQI | Category |
|---|---|---|
| 0.6 mi WSW | 12 | Good |
| 2.3 mi WSW | 65 | Moderate |
| 4.6 mi NNE | 52 | Moderate |
| 5.3 mi NW | 43 | Good |
| 5.4 mi N | 2 | Good |
Indianapolis has two air problems that show up in different seasons. Warm, still summer days cook up ground-level ozone over the metro, enough that the city runs its own Knozone alert program and the American Lung Association hands the Indianapolis-Carmel-Muncie area a failing grade for ozone. Year round, the fine soot from a freight-highway crossroads and the smoke that drifts down from Canadian wildfires, as it did in June 2023, keep particle pollution high.
What Canairy does for Indianapolis
A clear verdict
Not just a number — a plain-English call for Indianapolis: open the windows, or keep them shut.
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A heads-up before it's bad
Trend alerts catch the air turning, so you can close up the house before the smoke settles in.
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The summer ozone problem is bad enough that the city runs its own alert program
Indianapolis is one of the few cities that runs a public air-quality alert program under its own name. The Office of Sustainability operates Knozone, and on days when hot sun, light winds, and overnight buildup are forecast to push ground-level ozone into the orange Unhealthy for Sensitive Groups range, it declares a Knozone Action Day. These cluster from late spring through summer, when ozone forms fastest. The first Action Day of 2026 landed on June 4.
Ozone is not smoke you can see. It forms when sunlight cooks the exhaust from cars, trucks, and industry, which is why the worst days are often the hottest and calmest ones. The American Lung Association's 2025 State of the Air report gave the Indianapolis-Carmel-Muncie metro an F for ozone, ranking it 54th worst of 228 metro areas with about five unhealthy days a year. On a Knozone day, that ozone is the reason someone with asthma feels it on a run even when the sky looks clear.
The Crossroads of America runs on diesel
Indianapolis calls itself the Crossroads of America for a reason. The city is wrapped by the I-465 beltway and cut through by I-70, I-65, and I-69, and it is one of the busiest freight hubs in the country. That means a steady flow of long-haul trucks and the diesel exhaust that comes with them, concentrated along the interstates and the warehouse districts that feed them.
That traffic shows up in the particle numbers. The same 2025 State of the Air report ranked Indianapolis 21st worst in the nation for short-term particle pollution, with roughly 9.8 unhealthy days a year, and 11th worst for year-round particle pollution. Fine particles from diesel and combustion are small enough to reach deep into the lungs, and if you live or work near one of the big highways, your everyday exposure is higher than the citywide average suggests.
Wildfire smoke reaches Indiana too
Indianapolis is a long way from any forest fire, but smoke does not respect that distance. In June 2023, smoke from wildfires in Quebec and elsewhere in Canada drifted south and settled a visible haze over downtown, pushing air across Central Indiana into unhealthy territory. At the peak of that stretch, more than a third of the US population was under air-quality alerts from the same smoke.
The Lung Association pointed directly at extreme heat and wildfires as reasons air quality worsened in its most recent report, and that pattern is not a one-time event. When a smoke plume rides the jet stream over the Midwest, the particle levels in Indianapolis can climb for a day or two with little warning, which is exactly the kind of change worth catching early rather than finding out about from a scratchy throat.
Indianapolis air quality FAQ
What is the air quality in Indianapolis right now?
As of October 20, 2026 at 12:24 PM EDT, the air quality in Indianapolis, Indiana is AQI 43 — Good — with PM2.5 at 7.7 µg/m³, the median of 5 live PurpleAir sensors. Open the windows. Great for outdoor activity.
What is a Knozone Action Day in Indianapolis?
Knozone is the air-quality alert program run by the Indianapolis Office of Sustainability. On days when hot, sunny, still weather is forecast to push ground-level ozone into the orange Unhealthy for Sensitive Groups range, the city declares a Knozone Action Day and asks residents to cut back on driving, idling, and gas-powered equipment. They cluster in the summer months, when ozone forms fastest.
Why does Indianapolis have high particle pollution?
Indianapolis is a major freight crossroads, ringed by the I-465 beltway and crossed by I-70, I-65, and I-69, so diesel truck traffic and combustion are a steady local source of fine particles. Drifting wildfire smoke, like the Canadian smoke that hazed the city in June 2023, adds to it. In the 2025 State of the Air report the metro ranked 21st worst in the nation for short-term particle pollution and 11th worst for year-round levels.
What the AQI numbers mean
| AQI | Category | What it means for you |
|---|---|---|
| 0–50 | Good | Open the windows. Great for outdoor activity. |
| 51–100 | Moderate | Sensitive groups may want to take it slower outside. |
| 101–150 | Unhealthy for Sensitive Groups | Kids, elderly, and respiratory conditions stay closer to home. |
| 151–200 | Unhealthy | Skip outdoor exercise. Close windows. |
| 201–300 | Very Unhealthy | Limit time outside. N95 if you must go. |
| 301+ | Hazardous | Health emergency. Stay inside, run filtration if you have it. |
Canairy lets you tighten these bands if you’re more sensitive than the EPA default, so an alert can fire before the official category changes. How to read the Air Quality Index
Where these readings come from
The AQI at the top of this page is the median of the 5 curated PurpleAir sensors Canairy tracks in and around Indianapolis, with outliers set aside so that one sensor brought indoors — or parked beside a barbecue — cannot set the number for a whole city. Every sensor behind it is listed above with its distance and bearing from the city center. There is no black box here.
In the app, a place you save resolves the same way first. When no neighborhood sensor is reporting it falls back to the nearest EPA AirNow monitor, and anything modeled rather than measured is labelled a regional estimate rather than passed off as a sensor reading. How low-cost sensors compare to regulatory monitors
About Canairy
Canairy is free to download. The free plan covers one saved place with live readings, a plain-English verdict, and push alerts when the air crosses a threshold you choose. Paid plans add more places, faster refreshes, and SMS alerts. It is built by two parents in Sonoma County, California, who got tired of guessing whether it was safe to send the kids outside. Why we built it
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Air quality near Indianapolis
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