Air Quality in Pittsburgh, Pennsylvania — Live
Live readings from PurpleAir sensors across Pittsburgh — with free alerts the moment smoke drifts in.
AQI 54 from 5 PurpleAir sensors · Holding steady · data from PurpleAir
As of , the air quality in Pittsburgh, Pennsylvania is AQI 54 — Moderate and holding steady — with PM2.5 at 10.5 µg/m³, the median of 5 live PurpleAir sensors reading 14 to 55. Canairy's verdict: Mostly clear.
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 Pittsburgh: 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 Pittsburgh and Mount Lebanon, Bethel Park, McKeesport, Wilkinsburg. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Pittsburgh
The sensors Canairy reads in Pittsburgh are 41 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 |
|---|---|---|
| 1.2 mi NW | 39 | Good |
| 1.4 mi N | 54 | Moderate |
| 3.4 mi ENE | 55 | Moderate |
| 4.1 mi NW | 53 | Moderate |
| 5.1 mi E | 14 | Good |
Pittsburgh shed its 'Smoky City' reputation decades ago, and on most days now the air is good or moderate. But the region still carries the largest coke works in North America in the Mon Valley just south of town, the river valleys still trap what industry emits under winter inversions, and in recent summers wildfire smoke from Canada has drifted in over a city that once wrote the book on air pollution.
What Canairy does for Pittsburgh
A clear verdict
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What the air in Pittsburgh is doing next
| When | AQI | Expected air quality | Main pollutant |
|---|---|---|---|
| Today | 44 | Good | PM2.5 |
| Tomorrow | 40 | Good | ozone |
| Monday | 56 | Moderate | PM2.5 |
| Tuesday | 60 | Moderate | ozone |
| Wednesday | — | Moderate | ozone |
***A FLOOD WATCH IS IN EFFECT UNTIL 8 AM SATURDAY***Current Conditions at 4 PM EDT this Friday afternoon: Showers and a thunderstorm are moving through the area on a slow moving cold front. Showers will linger into Saturday before high pressure finally dries things out Sunday into Labor Day. Here are the forecast details: *** Saturday’s forecast: Mostly cloudy Saturday with a couple of showers. Winds will shift into the north during the afternoon as a cold front slips to the south. Highs will reach around 80 with fine particle (PM2.5) and ozone remaining in the good range. *** Sunday’s forecast: Mostly sunny Sunday with a nice afternoon. Comfortable with highs in the upper 70s. Ozone and PM2.5 concentrations will remain below the moderate range. *** Labor Day forecast: Lighter winds and less mixing will cause PM2.5 to rise again, perhaps to the moderate threshold. Highs in the lower 80s. *** Tuesday’s forecast: A little warmer Tuesday with increased weekday emissions along with a mostly sunny sky contribute to moderate PM2.5 and ozone concentrations. *** Extended forecast: Partly sunny and breezy Wednesday with a warm afternoon and moderate air quality continuing. A cold front approaching will bring showers and a thunderstorm late Wednesday and Wednesday night. Turning cooler late in the week with northwest flow and good air quality returning.---McAuliffe
Forecast from EPA AirNow for the Pittsburgh reporting area. Canairy watches the live sensors against it and tells you when the air actually crosses your threshold, rather than leaving you to check.
The Mon Valley still runs on coke, and the air downwind shows it
About 10 miles south of downtown, on a bend in the Monongahela River, sits U.S. Steel's Clairton Coke Works, the largest coke-making plant in North America. It bakes coal into coke for steelmaking around the clock, and it is the dominant remaining pollution source in the region. The Liberty and Clairton area has long been an EPA non-attainment zone for fine particle pollution, meaning it does not consistently meet the federal health standard.
The plant's risks are not hypothetical. On Christmas Eve 2018, a fire destroyed the works' desulfurization pollution controls, and for the next 102 days it released sulfur dioxide at roughly 25 times its normal levels across the valley. Hydrogen sulfide from the process still produces the rotten-egg smell that residents report through the Smell Pittsburgh app, and a 2019 settlement over the fire's fallout reached $8.5 million, most of it earmarked for plant improvements. If you live in Clairton, Liberty, or the towns downwind, a neighborhood-level reading tells you far more than a citywide average.
Why the valleys make Pittsburgh's air worse than the numbers suggest
Pittsburgh sits where three rivers meet, in a landscape of steep hills and narrow valleys. On cold, still mornings, especially in winter, a temperature inversion can settle over the Mon Valley: a lid of warm air aloft traps colder, dirtier air near the ground, and whatever industry and traffic put out has nowhere to go. The same geography that made the region an industrial powerhouse also concentrates its pollution.
The most infamous example happened just up the river. In 1948, a five-day inversion over Donora, 24 miles southeast of Pittsburgh, trapped emissions from the town's steel and zinc works so badly that 20 people died within days, around 50 more died over the following month, and nearly half of Donora's 14,000 residents fell ill. The Donora disaster became one of the events that spurred the modern Clean Air Act. The mills are mostly gone, but the valley shape that made the smog deadly is still there.
Wildfire smoke now reaches a city that thought it had left smoke behind
For most of the last century, Pittsburgh's air problems came from its own furnaces. That is changing. In June 2023, smoke from record Canadian wildfires drifted deep into the eastern United States, pushing air quality index readings above 400 in parts of Pennsylvania during the worst days and turning skies an orange haze. In Pittsburgh, the smoke was thick enough on June 29 to delay a Pirates game by 45 minutes.
Smoke like that arrives with little local warning and can change through the day as the plume shifts. It is a different kind of hazard than the steady industrial haze the region is used to, and it does not respect the usual seasonal rhythm. Watching live sensor readings is the practical way to know whether a smoky forecast has actually reached your street or is still hours away.
Pittsburgh air quality FAQ
What is the air quality in Pittsburgh right now?
As of September 5, 2026 at 8:10 AM EDT, the air quality in Pittsburgh, Pennsylvania is AQI 54 — Moderate — with PM2.5 at 10.5 µg/m³, the median of 5 live PurpleAir sensors. Sensitive groups may want to take it slower outside.
Why does the Mon Valley smell like rotten eggs or sulfur some mornings?
That smell is usually hydrogen sulfide from U.S. Steel's Clairton Coke Works, the largest coke plant in North America, about 10 miles south of the city. It tends to be worst on still mornings when a temperature inversion traps the emissions in the river valley. Residents track and report the odor through the Smell Pittsburgh app, and the Liberty-Clairton area is a federal non-attainment zone for fine particle pollution.
Is Pittsburgh's air still as bad as its Smoky City days?
No. EPA data from 2021 to 2024 shows Pittsburgh's air is generally good or moderate, a world away from the coal-smoke era that earned it the nickname. The catch is that the region's air is uneven: neighborhoods in the Mon Valley near heavy industry can have noticeably worse air than downtown or the hilltop suburbs on the same day, which is why a reading from a sensor near you matters more than a citywide number.
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 Pittsburgh, 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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