TLDR
The Cleveland area — seven counties in northeast Ohio — has been failing the federal ozone air quality standard since 2018. Monitoring data from 2023-2025 shows the area now meets the standard. EPA is proposing to officially redesignate Cleveland from "nonattainment" to "attainment." The improvement came from cleaner vehicles, a coal plant closure, stricter state rules, and regional power plant emission reductions. This is the system working the way it's supposed to.
What's Ozone, and Why Should You Care?
Ozone is the main ingredient in smog. Up in the atmosphere, ozone is helpful — it blocks ultraviolet radiation. But at ground level, it's a pollutant. It forms when two other pollutants — nitrogen oxides (NOx) and volatile organic compounds (VOCs) — react with sunlight. Hot, sunny days are the worst. (For a full explainer, see our article: What Is Ground-Level Ozone and Why Does It Matter?)
Breathing ground-level ozone irritates your lungs. For healthy adults, it can cause coughing, chest pain, and shortness of breath. For children, the elderly, and people with asthma or other lung conditions, it can trigger attacks and worsen symptoms. Long-term exposure is linked to permanent lung damage.
Think of it like a sunburn — but inside your lungs.
You can't see ozone. You can't smell it at low concentrations. But on a hot summer day in a city with traffic and industry, it's there. The federal standard is the government's way of saying: above this line, the air is unsafe.
What's the Standard?
In 2015, EPA set the ozone standard at 0.070 parts per million (ppm). To meet it, every air monitor in an area has to show a three-year average of the fourth-highest daily reading at or below 0.070 ppm. That might sound like a strange way to measure, but it's designed to account for the occasional bad day while still catching areas where bad air is a pattern.
Cleveland failed. In 2018, EPA designated the seven-county Cleveland area — Cuyahoga, Geauga, Lake, Lorain, Medina, Portage, and Summit counties — as "nonattainment." That's the official label that means: your air is worse than the standard allows.
Things kept getting worse. In 2022, Cleveland was bumped up to "Moderate" nonattainment. In 2024, it was reclassified as "Serious." Each step up brings stricter requirements — and more urgency.
What Changed?
A lot. Between 2017 and 2025, total NOx emissions in the Cleveland area dropped by 42% and VOC emissions dropped by 25%. Those are the two chemicals that combine in sunlight to form ozone. Less of both means less ozone.
Here's where the reductions came from:
Cleaner cars and trucks — the biggest factor
On-road NOx emissions dropped from 51.91 to 21.16 tons per ozone season day — a 59% decrease. This came from federal vehicle emission standards (Tier 2 and Tier 3) that required automakers to build cleaner engines and refiners to produce cleaner fuel. As older vehicles were replaced with newer ones, the fleet got cleaner every year. No one in Cleveland had to do anything — it happened automatically as people bought cars.
A coal plant shut down
The Avon Lake Power Plant stopped operating in April 2022, eliminating an estimated 1,069 tons of NOx per year. One facility, gone, and the air got measurably cleaner.
Regional power plant rules
Federal programs — the Cross-State Air Pollution Rule (CSAPR) and its updates — required power plants across the eastern U.S. to reduce NOx emissions. Since ozone doesn't respect state lines, cutting emissions from upwind power plants in other states helped Cleveland too.
State rules on consumer products and coatings
Ohio adopted stricter rules on VOC-containing consumer products and architectural coatings (paints, stains, sealants). These are small sources individually, but they add up across millions of households.
Is It Really Better, or Just Lucky Weather?
This is the right question. Ozone formation depends on heat and sunlight, so a run of cool summers could make the numbers look good without the air actually being cleaner. Ohio and EPA both addressed this.
An analysis by the Lake Michigan Air Directors Consortium looked at 22 years of data from the Cleveland area and found that while temperatures have actually trended upward — warmer summers, more hot days — ozone has trended downward. In other words, even as conditions got more favorable for ozone formation, less ozone formed. That points to real emission reductions, not weather luck.
EPA also checked whether the improvement was due to an economic downturn — fewer factories running, fewer trucks on the road. It wasn't. Employment and GDP in the Cleveland metro area both increased over the same period. The economy grew while the air got cleaner.
What Happens Now?
EPA is proposing to officially redesignate the Cleveland area from nonattainment to attainment. If finalized, that changes the legal status of the area and shifts it from "cleanup mode" to "maintenance mode."
Ohio has submitted a maintenance plan that projects continued declines in NOx and VOC emissions through 2038. The plan includes contingency measures — specific triggers that would require Ohio to take additional action if ozone starts creeping back up. If any monitor records a fourth-highest reading of 0.074 ppm or above, Ohio has to investigate. If the two-year average hits 0.071 ppm, Ohio has to implement new emission controls within 18 months.
The monitoring data — all 10 monitors passed
The 2015 ozone standard requires every monitor in the area to show a three-year average at or below 0.070 ppm. Cleveland has 10 monitors across six counties. The highest reading was 0.070 ppm — right at the line. Every other monitor came in below. The area passed, but just barely. That's worth keeping in mind: this isn't a story of pristine air. It's a story of air that now meets the minimum federal health standard.
Why This Matters Beyond Cleveland
Most of the environmental news right now is about rules being rolled back, deadlines being missed, and lawsuits being filed. This is a different story. This is the Clean Air Act doing exactly what it was designed to do: set a health-based standard, identify areas that don't meet it, require reductions, and then verify that the air improved.
It took eight years. It required federal vehicle standards, regional power plant rules, a coal plant closure, and state-level VOC rules all working together. No single action did it. The system worked because multiple levels of government — federal, state, and local — each did their part over a long period of time.
That's not exciting. It doesn't make for dramatic headlines. But for the roughly 2.8 million people living in those seven counties, the air they breathe this summer will be cleaner than it was in 2018. And there's a plan to keep it that way.
The bottom line
Cleveland's air quality improvement is proof that the system can work — but it takes years, it requires enforcement at every level, and the margins are thin. The area passed with a design value of exactly 0.070 ppm, the maximum allowed. One bad wildfire season or a relaxation of vehicle emission standards could push it back over the line. Clean air isn't a destination. It's a maintenance plan.
Sources: 91 FR 18355 (April 10, 2026), Proposed Rule: Air Plan Approval; Ohio; Redesignation of the Cleveland, OH Area to Attainment of the 2015 Ozone Standards; 91 FR 9800 (February 27, 2026), Proposed Clean Data Determination for the Cleveland Area; Ohio EPA Redesignation Request (December 8, 2025); Lake Michigan Air Directors Consortium (LADCO), meteorological and CART analyses; 40 CFR 50.19, 2015 Ozone NAAQS. Have a correction? Contact us.