Air Quality in Lewiston, Maine — Live
Live readings from PurpleAir sensors across Lewiston-Auburn — with plain-English alerts for hazy summer ozone days and still winter wood-smoke nights.
AQI 6 from 2 PurpleAir sensors · Trending down · data from PurpleAir
As of , the air quality in Lewiston, Maine is AQI 6 — Good and falling — with PM2.5 at 1.1 µg/m³, the median of 2 live PurpleAir sensors reading 5 to 7. 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 Lewiston: 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 Lewiston and Auburn, Sabattus, Lisbon, Greene. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Lewiston
The sensors Canairy reads in Lewiston agree right now — all 2 sit in the Good band, a 2-point spread — so the city-wide number is a fair description of the whole area today.
| From city center | AQI | Category |
|---|---|---|
| 2.5 mi WNW | 5 | Good |
| 6.5 mi SE | 7 | Good |
Most days, the air in Lewiston and Auburn is unremarkable in the best way — this stretch of the Androscoggin River valley doesn't have a wildfire season the way the West does. What it does have is two quieter, recurring problems: hot, hazy summer days when regional ozone builds up enough that the twin cities once carried their own federal nonattainment designation, and cold winter nights when wood-stove smoke settles into the valley instead of blowing away.
What Canairy does for Lewiston
A clear verdict
Not just a number — a plain-English call for Lewiston: open the windows, or keep them shut.
Smoke alerts
A push or text the moment the air crosses your threshold — and again when it clears.
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.
Every place you care about
Home, work, the kids' school — across Lewiston or across the country, on one screen.
Lewiston-Auburn once had its own ozone problem
From the early 1990s until the old federal ozone standard was revoked in 2005, the EPA classified Lewiston-Auburn as its own Moderate nonattainment area for ground-level ozone, covering all of Androscoggin and Kennebec counties — not folded into Portland's or Boston's designation, but named on its own. That happened because ozone doesn't need a local smokestack to form; it cooks up from vehicle exhaust and industrial emissions on hot, sunny, stagnant days, and inland Maine sits downwind of pollution carried up the whole Northeast corridor.
The standard that triggered that designation is gone, replaced by tighter modern rules, but the weather pattern that caused it hasn't changed. A hot, humid, windless day in July or August is still when Lewiston-Auburn's air is most likely to slide into the Moderate or Unhealthy for Sensitive Groups range — the kind of day that looks perfectly clear but is genuinely harder on a kid with asthma or someone doing yard work all afternoon.
Winter is when the wood smoke settles in
Maine relies on wood heat more than almost any state in the country. Census Bureau survey data puts roughly 8 percent of Maine households on wood as their primary heat source — second only to Vermont nationally. Lewiston and Auburn sit low in a river valley, and on the cold, calm nights that are common in a Maine winter, smoke from wood stoves and fireplaces has nowhere to go. It settles at ground level instead of dispersing the way it would on a windy day.
That's a different kind of pollution problem than the summer ozone story: it's fine particulate matter (PM2.5) instead of ozone, it shows up overnight and in the early morning instead of in the afternoon, and it's hyper-local — one street burning wood on a still night can be measurably worse than another a mile away. That's exactly the kind of gap a single official monitor for the whole metro area will miss, and a network of neighborhood sensors is built to close.
What actually changes on a bad-air day here
There's no dramatic sky-turns-orange moment in Lewiston-Auburn the way there is in a wildfire-prone city — the numbers move, but the sky usually still looks normal. That's exactly why a plain number matters more here, not less: on a hazy July afternoon or a still January night, the AQI can climb into a range worth changing your afternoon around even though nothing looks wrong outside.
If you or your kids deal with asthma, checking before an afternoon outdoors on a hot, still summer day is worth the ten seconds it takes. In winter the same logic applies to a still, cold evening — if your neighborhood is thick with wood smoke, cracking a window for fresh air can do the opposite of what you intend. Canairy is built to catch both kinds of days, not just the wildfire-smoke story that dominates most air-quality apps.
Lewiston air quality FAQ
What is the air quality in Lewiston right now?
As of September 14, 2026 at 8:09 AM EDT, the air quality in Lewiston, Maine is AQI 6 — Good — with PM2.5 at 1.1 µg/m³, the median of 2 live PurpleAir sensors. Open the windows. Great for outdoor activity.
Why did Lewiston-Auburn have its own ozone problem?
From the early 1990s until the federal standard was revoked in 2005, the EPA classified Lewiston-Auburn as its own Moderate nonattainment area for ground-level ozone, covering all of Androscoggin and Kennebec counties. Ozone builds up on hot, sunny, stagnant days from vehicle and industrial emissions carried in on regional winds, and that same weather pattern still produces the metro's worst summer air days even though the old designation is gone.
Does Lewiston get smoky in winter from wood stoves?
It can. Maine has one of the highest rates of wood heating in the country — around 8 percent of households burn wood as their primary heat source, second only to Vermont — and on cold, calm nights common to a Maine winter, that smoke settles into the Androscoggin River valley instead of blowing through. It's a quieter, more local problem than summer ozone, and it tends to show up overnight and in the early morning.
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 2 curated PurpleAir sensors Canairy tracks in and around Lewiston, 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 Lewiston
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