AIR QUALITY NJ

Air Quality in Princeton, NJ: Moderate (72 AQI)

AQI 72 · Moderate · Ozone · Updated 2026-07-18

Princeton's air quality is moderate. Unusually sensitive people should consider reducing prolonged outdoor exertion.

Data: EPA AirNow, FEMA National Risk Index Last verified: 2026-07-18

Average AQI

Moderate

AQI Category

Unhealthy Days

Wildfire Risk

Mold Score

ZIP Codes

What is AQI?

The Air Quality Index (AQI) is a standardized scale from 0 to 500 that measures air pollution levels. 0-50 is "Good," 51-100 is "Moderate," 101-150 is "Unhealthy for Sensitive Groups," and above 150 is "Unhealthy" for everyone. AQI tracks five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Princeton's average AQI of 72 falls in the "Moderate" range.

Air Quality Map: Princeton, NJ

Each dot represents a ZIP code. Color indicates AQI level. Tap a dot for details.

Good (0-50) Moderate (51-100) USG (101-150) Unhealthy (151+)

Air Quality by ZIP Code in Princeton

AQI varies across Princeton's 5 ZIP codes based on proximity to pollution sources and local geography.

ZIP Code	AQI	Category	Wildfire	Mold
08540	72	Moderate	20	49	View report →
08541	72	Moderate	20	41	View report →
08542	72	Moderate	20	52	View report →
08543	72	Moderate	20	33	View report →
08544	72	Moderate	20	25	View report →

Air Quality Overview

Princeton, New Jersey has moderate air quality with an average AQI of 72. Air quality is acceptable, though some pollutants may be a concern for a small number of people who are unusually sensitive to air pollution. The dominant pollutant is Ozone.

The Air Quality Index (AQI) is an EPA-standardized scale from 0 to 500. Values below 50 are "Good," 51-100 "Moderate," 101-150 "Unhealthy for Sensitive Groups," 151-200 "Unhealthy," 201-300 "Very Unhealthy," and above 300 "Hazardous."

Dominant Pollutant: Ozone

Ground-level ozone forms when pollutants from cars, power plants, and industrial facilities react with sunlight. Unlike stratospheric ozone, ground-level ozone is harmful to breathe.

Health effects of ozone exposure:

Irritation of the respiratory system
Reduced lung function
Aggravation of asthma and chronic lung diseases
Increased susceptibility to respiratory infections

Peak times: Ozone levels are typically highest on hot, sunny afternoons. Exercise outdoors in the morning when levels are lower.

Air Quality by ZIP Code in Princeton

AQI varies across Princeton's 5 ZIP codes based on proximity to pollution sources, traffic patterns, and local geography:

ZIP Code	AQI	Category	Wildfire Risk	Mold Score
08540	72	Moderate	20	49
08541	72	Moderate	20	41
08542	72	Moderate	20	52
08543	72	Moderate	20	33
08544	72	Moderate	20	25

Wildfire Smoke Risk

Princeton has an elevated wildfire smoke risk with an average smoke risk score of 20 (scale 0-100). There have been 50 fires recorded within 100 km of city ZIP codes.

Metric	Value
Avg. smoke risk score	20
Max smoke risk score	20
Fires within 100 km	50
High-risk ZIP codes	0

Wildfire smoke contains PM2.5, carbon monoxide, and volatile organic compounds. Even short-term exposure can trigger asthma attacks and respiratory distress.

Indoor Mold Risk

Princeton has an average mold risk score of 40 out of 100.

Factor	Value
Mold risk score	40/100
Average humidity	67% RH
High-risk ZIPs	0
Peak season	summer high

Mold risk is influenced by humidity levels, housing age (older homes have more moisture issues), flood history, and water infrastructure quality. Indoor humidity above 60% creates favorable conditions for mold growth.

Signs of mold problems: musty odors, visible growth on walls or ceilings, worsening allergies indoors, condensation on windows. Professional mold testing ($300-$600) can identify hidden issues.

Health Recommendations

With moderate air quality (AQI 72), most people can be active outdoors. Sensitive groups should take precautions:

Sensitive groups (asthma, COPD, heart disease): consider reducing prolonged outdoor exertion
Keep windows closed on high-pollution days
Use a HEPA air purifier in main living areas
Check AirNow.gov before outdoor exercise

Princeton vs. Nearby New Jersey Cities

How Princeton's air quality compares to nearby cities:

City	AQI	Category	Population
Princeton	72	Moderate	56,462
Freehold	150	USG	56,623
New Brunswick	163	Unhealthy	56,766
Union	164	Unhealthy	57,036

ZIP Codes in Princeton

Princeton covers 5 ZIP codes. Air quality can vary by neighborhood based on proximity to highways, industrial areas, and green spaces. Check your specific ZIP code for localized data.

Data Sources

Air quality: EPA AirNow - real-time and historical AQI data
Wildfire risk: FEMA National Risk Index
Mold risk: Derived from EPA, FEMA, Census ACS (humidity, housing age, flood history)
Monthly AQI: EPA Air Quality Statistics

Updated daily.

Frequently Asked Questions

Is the air safe to breathe in Princeton?

Princeton's average AQI is 72 (Moderate). Air quality is acceptable, but unusually sensitive individuals may experience respiratory symptoms during peak pollution times.

How many unhealthy air days does Princeton have?

Princeton experiences 25 unhealthy air quality days per year on average. During these days, everyone - not just sensitive groups - should reduce prolonged outdoor exertion.

What is the AQI in Princeton?

The average Air Quality Index (AQI) in Princeton is 72, categorized as Moderate. The primary pollutant is Ozone. AQI ranges from 0-500, where 0-50 is Good, 51-100 Moderate, 101-150 Unhealthy for Sensitive Groups, and 151+ Unhealthy.

What is the wildfire risk in Princeton?

Princeton has a wildfire risk score of 20 out of 100. Low wildfire risk means smoke events are uncommon, but regional fires can still temporarily affect air quality.

Is mold a concern in Princeton?

Princeton has a mold risk score of 40 out of 100, based on humidity, precipitation, and temperature data. Maintain good ventilation and address any water intrusion promptly to prevent mold growth.

Home → Cities → New Jersey → Princeton, NJ → Air Quality