Trenton Real-Time AQI Tracker
Get Alerts For Unhealthy AQI In Your Area
When air quality in your area reaches unhealthy levels, we'll send you a quick alert, along with expert tips on how to reduce your exposure.
What's Actually In Trenton Air Today?
What High AQI Means for Your Lungs in Trenton
How to Read AQI
The Air Quality Index (AQI) measures how polluted the air is and how it may affect your health.
0–50 (Good): Air quality is satisfactory.
51–100 (Moderate): Acceptable, but some pollutants may pose minor concerns.
101–150 (Unhealthy for Sensitive Groups)
151–200 (Unhealthy)
201–300 (Very Unhealthy)
301+ (Hazardous)
Moderate
Still okay for most, but if you have asthma or allergies, take it easy and avoid long outdoor workouts.
Shop MERV 11 filters→What's the Right Filter for Your AQI Level?
Check Today's Live Real Time Air Quality Index AQI Map in Trenton, NJ Now
TL;DR
Filterbuy's live map above shows Trenton's Air Quality Index (AQI) right now and the pollutant behind it: usually ozone on hot afternoons, or PM2.5, the tiny particles in smoke and exhaust. If the map reaches 100, Filterbuy's action line, switch to a MERV 13 filter, set the fan to On, run portable HEPA cleaners and close up the house.
Key Takeaways
Mercer County earned an F for ozone in the American Lung Association's 2025 report and ranked worst in New Jersey.
New Jersey's environmental agency (NJDEP) measures PM2.5 at the Trenton Public Library and ozone at Rider University in Lawrenceville.
MERV 13 is the tier Filterbuy recommends for smoke. Homes without ducts should rely on portable HEPA air cleaners.
How to Read the Trenton AQI Map Above
Each marker is a monitoring station colored by its worst pollutant. Filterbuy's rule is to read the pollutant label before the color, since the label tells you what to do inside.
In Trenton, those readings come from the New Jersey Department of Environmental Protection (NJDEP). PM2.5 is measured at the Trenton Public Library station on Academy Street, and ozone at Rider University in Lawrenceville, about 4 miles north. Air along Route 1 or Route 29 may differ from either station.
The map pulls these readings through EPA's AirNow and refreshes hourly. For the rest of the state, open Filterbuy's live New Jersey AQI map.
Is Trenton's Air Safe Today? What Each AQI Color Means
Green or yellow means nearly everyone can go about their day. Orange is where sensitive groups should start cutting back, and at red, everyone should. If you have asthma, COPD or a heart condition, follow your doctor's advice and AirNow guidance. Filterbuy's AQI color chart guide explains each band.
| AQI | Category | Who should adjust | A practical Trenton move |
|---|---|---|---|
| 0–50 | Good (green) | No one | Open windows; good day to air out a closed-up rowhome |
| 51–100 | Moderate (yellow) | Unusually sensitive people | Keep plans; get a MERV 13 in and a spare on hand before smoke arrives |
| 101–150 | Unhealthy for Sensitive Groups (orange) | Kids, older adults, people with lung or heart disease | Sensitive groups ease off outdoors; take the four indoor steps below |
| 151–200 | Unhealthy (red) | Everyone | Same four steps; inspect the filter more often and keep replacements on hand |
| 201–300 | Very Unhealthy (purple) | Everyone | Follow AirNow and NJDEP guidance first; stay in a clean room; filtration is one layer |
| 301+ | Hazardous (maroon) | Everyone | Follow official guidance first, including any relocation advice; use a clean room |
AQI ranges and categories follow the U.S. EPA Air Quality Index. Trenton moves are Filterbuy guidance.
What to Do When Trenton Hits AQI 100
AQI 100 is the top of Moderate, and it's where Filterbuy tells customers to act. Check AirNow and NJDEP for guidance on time outdoors first. Then, at home:
Put a MERV 13 filter in your HVAC. It's the whole-home layer.
Set the thermostat fan to On. Auto filters only while heating or cooling.
Run a portable HEPA air cleaner in each occupied room, bedrooms first.
Close up the house. Shut windows and doors; skip candles, frying, smoking and unsealed vacuums.
EPA recommends a filter rated MERV 13 or higher in your central system during smoke events. The AQI 100 trigger and the room-by-room cleaners are Filterbuy's recommendations. EPA's guidance centers on one clean room.
Trenton Air Quality Forecasts and What a Code Orange Alert Means
NJDEP posts a daily forecast on its AQI Today page. The Air Quality Partnership, run by the Delaware Valley Regional Planning Commission (DVRPC), covers the greater Philadelphia region, including Mercer County. EnviroFlash, a free EPA and NJDEP service, sends alerts by email or text.
When an alert says Code Orange, the forecast AQI is 101–150; Code Red means 151–200.
What Pollutes Trenton's Air: Ozone and PM2.5
Ozone forms when traffic and industrial gases react in sunlight. Sitting on the I-95 corridor between Philadelphia and New York, Trenton picks up ozone from both, and traffic on Route 1, Route 29, I-295 and I-195 adds more.
PM2.5 comes mostly from traffic exhaust and smoke. On cold, still nights, it settles close to the ground instead of dispersing.
Trenton's Air Quality Calendar: What to Expect Each Season
Those pollutants take turns through the year. Filterbuy built this calendar from state fire and air data, summarized on our New Jersey wildfire and smoke map.
| When | What drives Trenton AQI | Your move |
|---|---|---|
| Mid-Mar to mid-May | Peak New Jersey wildfire season, mostly in the Pine Barrens | Install a fresh MERV 13 before May |
| May to Sept | Ozone on hot, still afternoons; drifting Canadian smoke | Exercise in the morning; check the pollutant label daily |
| Sept to Nov | A second, smaller fire season | Swap out the filter that ran all summer |
| Dec to Feb | Still nights trap wood smoke and traffic PM2.5 | Skip wood fires on calm evenings; run the fan on smoky nights |
Compiled by Filterbuy from New Jersey Forest Fire Service and NJDEP data. Seasons overlap; the driver named is the usual leader.
How Trenton's Air Compares With the Rest of New Jersey
The American Lung Association gave Mercer an F for ozone in its 2025 report and ranked it worst in New Jersey. Under New Jersey's 2020 environmental justice law, almost all of Trenton's census blocks are classified as overburdened communities.
Wildfire Smoke: Trenton's Biggest Air Quality Wildcard
On June 7, 2023, Canadian wildfire smoke led NJDEP to issue a Code Red alert that covered Mercer County, and hourly readings in New Jersey reached an AQI of 458 that month, according to NJ Spotlight News.
During smoke, follow AirNow and NJDEP guidance, then take the four steps above. Check your filter often and replace it when it looks dark brown or black, which can be well before its normal interval. Keep a spare on hand. Filterbuy's New Jersey wildfire and smoke map shows where plumes are headed.
Keeping Smoke and Soot Out of an Older Trenton Home
Roughly four in ten Trenton homes were built before 1940, and attached rowhouses are the most common type. Many leak air around windows and party walls and heat with radiators rather than ducted systems.
Without ducts, there's no filter slot, so portable HEPA air cleaners are your primary defense. EPA advises choosing one whose smoke CADR (clean air delivery rate) is at least two-thirds of the room's square footage, so a 300 sq ft bedroom needs a smoke CADR of about 200. Skip ionizers and ozone generators, since EPA advises against air cleaners that produce ozone.
Build a box-fan cleaner with MERV 13 filters using the EPA's DIY air cleaner guide. Use a certified fan made in 2012 or later, and don't leave it running unattended. A DIY unit is a stopgap, not a replacement for a certified air cleaner.
Pro tip from the Filterbuy team: In ducted rowhomes, older returns can pull air from the basement; sealing return-side gaps helps.
Which Filter the Trenton AQI Calls For
For smoke, the answer is MERV 13. Filterbuy's MERV rating guide for high-AQI days covers the full comparison.
| AQI on the map | What to expect | HVAC filter | Also do |
|---|---|---|---|
| 0–50 | Everyday dust and pollen | MERV 8 or MERV 11 | Change on your normal schedule |
| 51–99 | Smoke may be on the way | MERV 13, installed early | Keep a spare on hand |
| 100 and up | Smoke or smog | MERV 13 | Fan On; portable HEPA cleaner in each occupied room; house closed up |
| During smoke | Filter loading fast | Fresh MERV 13 | Replace when it looks dark brown or black |
MERV 13 is the tier Filterbuy recommends for smoke. Check the size as you would for any filter.
EPA notes that most furnaces and HVAC systems can use a MERV 13 filter without equipment problems, as long as it's replaced often. HEPA belongs in portable cleaners, not your HVAC slot; our MERV 13 vs. HEPA guide explains why.
Fit matters too: a filter even slightly too small lets air slip past it unfiltered. Rowhome grilles are often odd sizes, which is why Filterbuy cuts custom air filters alongside 600+ stock sizes. Find MERV 13 in your size, and set up filter auto-delivery so a spare is always on hand.
The Two-Signal Check
After more than a decade of making filters in the USA, Filterbuy has learned the AQI tells only half the story. Once you've taken the four steps, check two signals:
Read the pollutant. Pleated filters capture particles, not gases like ozone, so on ozone days a closed house does most of the work. On PM2.5 days, your filters carry the load.
Read your filter. If it looks dark brown or black, replace it, even if it's early.
"Every time wildfire smoke reaches the Northeast, we see the same thing on our end: customers who normally reorder filters every 90 days start reaching out much sooner, because the filter is already visibly loaded with soot."
David Heacock, Founder & CEO, Filterbuy
Supporting Statistics
112%
1. Smoke sent asthma ER visits soaring.
On June 7, 2023, the Code Red covered Mercer County.
NJ emergency rooms logged 199 asthma visits that day.
That is more than double the prior two-week average of 94.
Source: New Jersey Department of Health, March 2025
90%
2. Most exposure happens indoors.
Americans spend about 90% of their time indoors.
Some pollutants run 2 to 5 times higher inside than outside.
Source: U.S. EPA, Report on the Environment
706,882
3. New Jersey kids carry much of the burden.
706,882 New Jersey children breathe unhealthy air, based on 2022–2024 data.
Source: American Lung Association, "State of the Air" 2026
Frequently Asked Questions
What is the air quality in Trenton today?
Filterbuy's live Trenton AQI map at the top of this page shows current conditions.
Is the air quality bad in Trenton today?
It's bad for sensitive groups when the map shows orange (101–150) and bad for everyone at red (151) or higher.
What does Trenton's PM2.5 reading mean?
Trenton's PM2.5 reading measures fine particles from traffic exhaust and smoke, the pollutant MERV 13 filters and portable HEPA cleaners capture.
Where can I get Trenton air quality alerts?
Use the Filterbuy AQI alert sign-up on this page, or EnviroFlash, the free EPA and NJDEP service.
What MERV rating do I need for wildfire smoke?
MERV 13. EPA recommends a filter rated MERV 13 or higher in your central system during smoke events. Filterbuy tells customers to switch when the AQI reaches 100.
Glossary
Air Quality Index (AQI): The EPA's 0–500 scale with six color-coded health categories.
Ground-level ozone: A lung irritant formed in sunlight; the main ingredient in smog.
PM2.5: Fine particulate matter 2.5 micrometers or smaller, small enough to reach deep into the lungs.
NJDEP: New Jersey Department of Environmental Protection, which runs the state's air monitors.
MERV: Minimum Efficiency Reporting Value, a 1–16 HVAC filter efficiency rating.
HEPA: A filter standard that captures at least 99.97% of 0.3-micron particles, used in portable air cleaners rather than HVAC systems.