Data: EPA AirNow, FEMA National Risk Index Last verified: 2026-05-03

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. Pasadena's average AQI of 61 falls in the "Moderate" range.

How do wildfires affect air quality?

Wildfire smoke contains fine particulate matter (PM2.5) that can travel hundreds of miles and dramatically spike AQI readings. During fire season, even cities far from active fires can experience unhealthy air. HEPA air purifiers (rated for PM2.5) are the most effective indoor protection. Check AirNow.gov for real-time conditions during fire season.

Air Quality Map: Pasadena, CA

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 Pasadena

AQI varies across Pasadena's 26 ZIP codes based on proximity to pollution sources and local geography.

ZIP Code	AQI	Category	Wildfire	Mold
91101	61	Moderate	91	30	View report →
91102	61	Moderate	91	18	View report →
91103	61	Moderate	91	44	View report →
91104	61	Moderate	91	44	View report →
91105	61	Moderate	91	47	View report →
91106	61	Moderate	90	38	View report →
91107	61	Moderate	91	47	View report →
91109	61	Moderate	54	22	View report →
91110	61	Moderate	91	18	View report →
91114	61	Moderate	91	18	View report →
91115	61	Moderate	91	18	View report →
91116	61	Moderate	91	18	View report →
91117	61	Moderate	91	18	View report →
91121	61	Moderate	91	18	View report →
91123	61	Moderate	91	18	View report →

Showing 15 of 20 ZIP codes. View all.

Air Quality Overview

Pasadena, California has moderate air quality with an average AQI of 61. 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 Pasadena

AQI varies across Pasadena's 26 ZIP codes based on proximity to pollution sources, traffic patterns, and local geography:

Showing 15 of 26 ZIP codes. Check your specific ZIP for detailed data.

Wildfire Smoke Risk

Pasadena has an elevated wildfire smoke risk with an average smoke risk score of 90 (scale 0-100). There have been 1,062 fires recorded within 100 km of city ZIP codes.

Metric	Value
Avg. smoke risk score	90
Max smoke risk score	91
Fires within 100 km	1,062
High-risk ZIP codes	26

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

Pasadena has an average mold risk score of 25 out of 100.

Factor	Value
Mold risk score	25/100
Average humidity	57% RH
High-risk ZIPs	0
Peak season	winter 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 61), 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

Pasadena vs. Nearby California Cities

How Pasadena's air quality compares to nearby cities:

ZIP Codes in Pasadena

Pasadena covers 26 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.