Researchers wired fifty Monroe County houses with particle monitors, inside and out, from November straight through April. The air inside measured dirtier than the air outside.
That one finding flips what most of us assume about living here. Our outdoor air is fine. Genuinely fine, by national standards. Which is exactly why almost nobody in this town stops to think about what they’re breathing at home.
Here’s what you can do about it. Test for radon. Put a correctly sized filter in your return and actually change it. Push moisture out of the house instead of around it, and check the regional reading before you throw the windows open.
Why that matters more here than somewhere warmer comes down to geography. Rochester sits on the south shore of Lake Ontario, and our heating season runs close to seven months. Seven months of doors shut, storm windows down, the furnace cycling, and whatever your kitchen and basement produce circulating through the same rooms. You can’t see any of it. That’s the whole problem.
TL;DR Quick Answers
Air Quality Rochester NY
Rochester's outdoor air quality is good by national standards. That number won't tell you what you're actually breathing. Local research found indoor fine particles running higher than outdoor levels all heating season, and the worst pollutant here shows up on no index at all.
Outdoor AQI: generally good. Watch the Eastern Lake Ontario regional forecast, not a city-level app.
Indoor reality: 50 Monroe County homes averaged a 1.1 indoor-to-outdoor particle ratio in winter, 1.7 with a combustion source running.
The invisible one: radon. This county's flagged for high potential and it appears on no air quality index anywhere.
When it spikes: Canadian wildfire smoke has shoved this region past AQI 150, and it arrives fast.
What to do: test for radon, fit and change your filter properly, vent moisture outdoors, check the regional reading before opening windows.
Top Takeaways
Indoor fine particles in 50 local homes averaged higher than outdoor levels all heating season.
Advisories here cover the Eastern Lake Ontario region, not the city, so watch the regional forecast rather than a city-level app.
Radon is the highest-consequence indoor air issue in this county, and it appears on no air quality index anywhere.
Winter is the right season to test for it, because the closed-house condition the test needs is already how you’re living.
Filter fit beats filter rating. Air that goes around a filter never gets filtered.
Seal without ventilating and you concentrate whatever is already indoors.
What the air outside your Rochester home is actually doing
We get measured more carefully than most cities our size, and I had no idea until I looked. Air quality Rochester NY monitoring benefits from that unusually strong local network. The New York State Department of Environmental Conservation runs a National Air Toxics Trends Station here. Two exist statewide. The other sits in the Bronx. DEC also put one of its three statewide near-road monitors here, where two interstates and a freight line meet.
So the claim that our air is clean isn’t civic pride. It’s instrumented.
What caught me off guard was how warnings get issued. DEC doesn’t forecast city by city. Monroe County belongs to a block the state calls Eastern Lake Ontario, lumped in with Wayne, Oswego, Jefferson, and northern Cayuga. One advisory covers all of it. Watch a city-level number on your phone and you’re watching a different unit than the state does when it tells people to stay indoors.
Then there’s smoke. Canadian wildfire plumes have drifted across the lower Great Lakes more than once and shoved this region past an AQI of 150, where the air turns unhealthy for everybody, not just people with asthma. Those events show up fast. Pulling up the live air quality index for Rochester takes ten seconds and tells you whether to open a window or shut the house and run the fan.
Why our long heating season is the real indoor problem
Back to those fifty houses.
Teams from Clarkson University and the University of Rochester Medical Center ran particle monitors inside and outside 50 single-family homes in Monroe County, November through April, across two winters. The mean indoor-to-outdoor ratio landed at 1.1. With a combustion source running, it climbed to roughly 1.7.
Look at the shape of the data and the mystery evaporates. Indoor levels spiked in the morning, spiked again at dinner, and ran higher on weekends. That’s not a pollutant. That’s people being home. The study also caught short-term jumps above 100 micrograms per cubic meter in houses with wood stoves and houses without them.
None of this is exotic. It’s dinner, the vacuum, the candles, the dog, and a house sealed tight against a Rochester January doing exactly what we asked. The better insulated your home, the fewer places those particles have to go.
Radon: the problem no app will ever show you
Monroe County is flagged for high radon potential, and this is the part I’d move to the top of your list.
Radon is radioactive gas working up out of soil and rock, through foundation cracks, slab-footing joints, sump openings, gaps around pipes. You can’t see it, smell it, or taste it. The Centers for Disease Control and Prevention calls it the second leading cause of lung cancer deaths in this country, behind cigarettes.
New York recommends fixing a home at 4 picocuries per liter or higher, and says it’s reasonable to consider fixing between 2 and 4. There’s no known safe level.
Two things make this a Rochester problem specifically. Radon concentrates in basements, and around here basements are where we live: rec rooms, laundry, home offices, the kid’s bedroom nobody wanted upstairs. An accurate test also needs the house shut tight, every door and window closed, for 24 hours beforehand and throughout. In Georgia that’d be a hassle. Here it’s just a Tuesday in February.
State kits run about twelve dollars through the Department of Health, and the county will point you toward certified testers. A good reduction system cuts levels dramatically. You’ll never smell the difference. That’s why the number matters.
What to change at the filter
There’s no single right MERV number for a house in this climate, and anybody who hands you one without asking about your system is guessing.
Fit matters more than rating. A gap at the edge of the slot lets air slide around the filter instead of through it, and bypass undoes a high-rated filter faster than a low rating could. Measure the slot yourself. Don’t trust the size printed on the old one.
Then match the rating to what your equipment can handle. Denser filters push back harder. On an older furnace with a tired blower, jumping straight to the highest rating on the shelf can choke airflow enough to hurt your comfort and the machine. Move up one step. Watch how it runs.
Change it on a date, not on a look. By the time a filter looks bad it’s been restricting airflow for weeks. And treat smoke days as their own category, because during a heavy plume that filter loads far faster and whatever interval works in October won’t hold.
One caution the EPA is blunt about: filtration supplements source control and ventilation, it doesn’t replace them. Get rid of whatever’s making the particles first. Bring in clean outdoor air second. Filter third. A better filter while your range hood vents into a cabinet fixes the third problem and ignores the first.
Ventilation and moisture in a cold climate
Everybody here gets told to seal and insulate, and that advice is sound for comfort and for what you pay to heat the place. It also carries a warning left out of most of the pitch. ENERGY STAR says it plainly in its own attic guidance: sealing a home can trap carbon monoxide, radon, and volatile organic compounds inside. Tighten the envelope without adding ventilation and you’ve traded one problem for a worse one.
The fixes aren’t glamorous. They work anyway.
Vent moisture out, not sideways. Bath and kitchen fans have to terminate outdoors, and so does the dryer. A fan dumping into an attic just relocates moisture from a room you notice to a cavity you don’t.
Hold relative humidity between 30 and 50 percent. Monroe County environmental health names that range for keeping dust mites and mold in check.
Dry water-damaged material inside 24 hours. Carpet and drywall left wet past a day stop being a cleanup and start being a biology problem.
Keep attic and crawl space humidity under 50 percent so indoor moisture isn’t condensing on cold framing over your head.
Run the exhaust fan every single time you cook. In a sealed house, dinner’s the biggest particle event of the day.
“The houses that surprise people are the tight, well-kept ones. Owners figure a better-sealed home means better air, and where outdoor pollution is concerned they’re right. What changes is that everything made inside now stays inside longer. The answer is almost never a more aggressive filter. It’s finding what produces the particles and giving the house a deliberate way to exhale.”
7 Essential Resources
All checked live. Government and nonprofit primary sources only.
1. NYSDEC Air Quality Index Forecast and Current Observations – the state forecast, including the Eastern Lake Ontario region Monroe County sits in.
2. New York State Department of Health: Radon – action levels, low-cost test kits, and when to retest.
3. Monroe County Environmental Health: Indoor Assessment – county guidance on mold, humidity targets, and indoor air complaints. Call (585) 753-5075.
4. EPA: Improving Indoor Air Quality – the source control, ventilation, and air cleaning framework.
5. AirNow Fire and Smoke Map – particle readings and smoke plume tracking, built by EPA and the U.S. Forest Service.
6. ENERGY STAR: Attic Air Sealing Project – including the warning that sealing a home can trap carbon monoxide, radon, and VOCs.
7. Wadsworth Center Radon Monitoring Program – New York radon maps and measurement tables by town.
3 Statistics
1. Indoor fine particles in 50 Monroe County homes averaged a 1.1 indoor-to-outdoor ratio across the heating season, climbing to roughly 1.7 with a combustion source in use. Aerosol and Air Quality Research, Ferro et al.
2. Radon is the second leading cause of lung cancer deaths in the United States, responsible for roughly 21,000 deaths a year, with an action level of 4 pCi/L. Centers for Disease Control and Prevention
3. The national annual standard for fine particle pollution is 9 micrograms per cubic meter, the benchmark used to grade every county in the 2026 State of the Air report. American Lung Association
Monroe County data shows that indoor particle levels can rise above outdoor levels and that radon and fine particles remain important health considerations, while air-purifying houseplants can complement broader indoor air-quality habits by adding greenery to the home environment.
Final Thoughts and Opinion
If one idea sticks with you, make it this. Stop treating outdoor air quality as the whole story and start treating the heating season as an exposure season.
Seven months of a closed house isn’t a footnote to our climate. Most air quality advice assumes you live somewhere you can open a window most of the year. That assumption doesn’t survive February on Lake Ontario.
My opinion, for what it’s worth: the radon test is the highest-value thing here, and it’s the one almost everybody skips because nothing about it feels urgent. A filter change gives you something to look at. A radon test gives you a number that either lets you quit worrying or tells you something worth knowing years early.
The rest is maintenance. Vent the moisture, fit the filter right, check the regional reading when the sky goes hazy. None of it’s hard, and all of it compounds across a long winter.
Frequently Asked Questions
Is the air quality in Rochester NY actually bad?
By national standards, no. Our outdoor readings are good and this city is monitored more closely than most of its size. But clean outdoor air tells you almost nothing about the air inside a house that stays shut most of the year.
What MERV rating should I use in a Rochester home?
Depends on your system, not your zip code. Higher-rated filters push back harder against airflow, and older furnaces don’t always tolerate a big jump. MERV 8 pleated HVAC furnace air filters can be a practical starting point for many systems before moving to a higher rating. Step up one level at a time. Sizing and a flush seal matter more than the number.
When should I test my home for radon?
Winter. Your doors and windows are already shut, and an accurate short-term test needs the house closed for 24 hours beforehand and throughout. New York recommends retesting every five years, or every two if you’ve got a mitigation system.
Does opening windows help indoor air quality in winter?
Yes, on mild days when the regional reading is good. The trouble is that our coldest stretch is also when ventilation is least practical, which is why mechanical exhaust and humidity control carry more weight here than in milder places.
What should I do when wildfire smoke reaches the region?
Shut the windows and doors. Run your system fan continuously so air keeps moving through the filter, skip anything that adds particles indoors like candles or frying, and expect that filter to load faster. Check the smoke map instead of guessing from the sky.
Call to Action
Pick one thing this week. If your basement is finished and you’ve never tested it, order a radon kit. If you can’t remember your last filter change, go measure the slot before you buy a replacement. If airflow problems point to leaks or damage in the system, make duct repair a priority. And if the sky looks hazy tomorrow, check the regional reading before you decide the air feels fine.
None of these takes an afternoon, and all pay off across a winter that’s going to keep your house shut either way. You’re the one deciding what your family breathes for the next seven months. Worth knowing what’s in it.
