Air Quality in Rock Hill, South Carolina — Live
Live readings from PurpleAir sensors across Rock Hill — with free alerts when summer ozone pushes the air past a level you set.
AQI 47 from 3 PurpleAir sensors · Trending down · data from PurpleAir
As of , the air quality in Rock Hill, South Carolina is AQI 47 — Good and falling — with PM2.5 at 8.4 µg/m³, the median of 3 live PurpleAir sensors reading 39 to 56. 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 Rock Hill: weeds pollen is the strongest of the three at a high 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 Rock Hill and Fort Mill, Tega Cay, York, Clover. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Rock Hill
The sensors Canairy reads in Rock Hill are 17 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 |
|---|---|---|
| 1.5 mi SSW | 47 | Good |
| 7.9 mi SE | 39 | Good |
| 9.4 mi NNE | 56 | Moderate |
Rock Hill's air is good most of the year — this is a humid Piedmont city where a hazy sky is usually just heat and moisture, not pollution. Summer is the exception: hot, sunny, windless afternoons cook Charlotte-area traffic exhaust into ground-level ozone, and the York County side of the metro spent years on the EPA's nonattainment list before finally clearing it.
In Rock Hill that mostly means summer ozone days, not wildfire smoke — but the same idea holds: check before you commit to an afternoon outside, not after your throat starts to itch.
What Canairy does for Rock Hill
A clear verdict
Not just a number — a plain-English call for Rock Hill: 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 Rock Hill or across the country, on one screen.
Rock Hill's ozone problem came from Charlotte, not from Rock Hill
York County was listed by the EPA as part of a Charlotte ozone nonattainment area under two different federal standards before finally reaching maintenance status. The 1997 8-hour ozone standard's "Charlotte-Gastonia-Rock Hill, NC-SC" nonattainment area was redesignated to maintenance on December 26, 2012. After the EPA tightened the standard again in 2008, the York County portion of the renamed "Charlotte-Rock Hill, NC-SC" area — classified Marginal — didn't reach maintenance status until January 11, 2016.
That history is still being actively managed, not just remembered: South Carolina's Department of Environmental Services submitted a second maintenance plan for the York County area in September 2023, projecting it stays under the 2008 ozone standard through 2036. The pollution behind those numbers mostly forms downwind of Charlotte's traffic and Mecklenburg County's industry, then settles over Rock Hill and the rest of York County on hot, still afternoons — a reminder that a county line doesn't stop ozone.
Summer heat, not winter smoke, is Rock Hill's air quality season
Rock Hill sits in the Piedmont with a humid subtropical climate that pushes July highs to around 91°F. Ozone forms when sunlight cooks vehicle exhaust and other emissions in hot, still air, so the worst readings tend to land on windless July and August afternoons — not in wildfire season, which barely touches this part of the Southeast most years.
The city's own growth adds to the mix. Rock Hill is the fourth-largest city in the Charlotte metro after Charlotte, Concord, and Gastonia, and York County has been one of South Carolina's fastest-growing counties as Charlotte commuters push south down I-77 into Fort Mill, Tega Cay, and Rock Hill itself. More cars idling in more traffic on hot afternoons is close to the exact recipe that put York County on the nonattainment list in the first place.
What to actually do on a high-ozone afternoon
Ozone typically peaks in the mid-to-late afternoon and drops off by evening, so the simplest fix is timing: move a run, a bike ride, or a kid's soccer practice to the morning instead of 3 or 4 p.m. when the number is highest. Mowing the lawn or filling up the gas tank in the evening instead of midday helps too — both release the same volatile compounds that cook into ozone in strong sun.
Canairy is built to answer the question before you walk out the door instead of after you're already coughing. Set a threshold for your house, your kids' school, or wherever they play summer ball, and you'll get a plain-English alert when the air crosses it — no need to remember to check a map every July afternoon.
Rock Hill air quality FAQ
What is the air quality in Rock Hill right now?
As of September 14, 2026 at 11:00 AM EDT, the air quality in Rock Hill, South Carolina is AQI 47 — Good — with PM2.5 at 8.4 µg/m³, the median of 3 live PurpleAir sensors. Open the windows. Great for outdoor activity.
Why does Rock Hill's ozone get worse in summer?
Ground-level ozone forms when sunlight reacts with vehicle exhaust and other emissions in hot, still air, and Rock Hill's humid Piedmont summers — July highs around 91°F — provide exactly that. The York County portion of the Charlotte metro spent years on the EPA's ozone nonattainment list before reaching maintenance status in 2016, and afternoon traffic along I-77 still drives the worst days.
Is Rock Hill's air currently in violation of federal standards?
No. York County is currently in maintenance status for ozone, meaning it meets the federal standard but is still required to keep proving it will stay that way. South Carolina's second maintenance plan, submitted in 2023, projects the area stays under the 2008 ozone standard through 2036.
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 3 curated PurpleAir sensors Canairy tracks in and around Rock Hill, 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 Rock Hill
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