AIR QUALITY CA

Air Quality in Costa Mesa, CA: Good (44 AQI)

AQI 44 · Good · Ozone · Updated 2026-05-03

Costa Mesa's air quality is good. Air pollution poses little or no risk.

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

Average AQI

Good

AQI Category

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. Costa Mesa's average AQI of 44 falls in the "Good" 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 by ZIP Code in Costa Mesa

AQI varies across Costa Mesa's 3 ZIP codes based on proximity to pollution sources and local geography.

ZIP Code	AQI	Category	Wildfire	Mold
92626	44	Good	47	48	View report →
92627	44	Good	47	49	View report →
92628	44	Good	47	26	View report →

Air Quality Overview

Costa Mesa, California has good air quality with an average AQI of 44. This means air pollution poses little or no risk. The dominant pollutant measured 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 Costa Mesa

AQI varies across Costa Mesa's 3 ZIP codes based on proximity to pollution sources, traffic patterns, and local geography:

ZIP Code	AQI	Category	Wildfire Risk	Mold Score
92626	44	Good	47	48
92627	44	Good	47	49
92628	44	Good	47	26

Wildfire Smoke Risk

Costa Mesa has an elevated wildfire smoke risk with an average smoke risk score of 47 (scale 0-100). There have been 90 fires recorded within 100 km of city ZIP codes.

Metric	Value
Avg. smoke risk score	47
Max smoke risk score	47
Fires within 100 km	90
High-risk ZIP codes	3

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

Costa Mesa has an average mold risk score of 41 out of 100.

Factor	Value
Mold risk score	41/100
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 good air quality (AQI 44), Costa Mesa residents can enjoy outdoor activities without significant restrictions. General tips:

Monitor AQI during wildfire season for temporary spikes
Use HEPA air purifiers indoors if you have respiratory conditions
Maintain indoor humidity between 30-50% to prevent mold

Costa Mesa vs. Nearby California Cities

How Costa Mesa's air quality compares to nearby cities:

City	AQI	Category	Population
Costa Mesa	44	Good	110,450
Azusa	126	USG	110,159
Santa Maria	43	Good	109,974
Highland	159	Unhealthy	108,629

ZIP Codes in Costa Mesa

Costa Mesa covers 3 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 Costa Mesa?

Yes — Costa Mesa's average AQI is 44 (Good). Air pollution poses little or no risk for the general population.

How many unhealthy air days does Costa Mesa have?

Costa Mesa has zero recorded unhealthy air quality days, which is excellent. Air quality can still vary seasonally due to wildfire smoke, pollen, or industrial activity.

What is the AQI in Costa Mesa?

The average Air Quality Index (AQI) in Costa Mesa is 44, categorized as Good. 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 Costa Mesa?

Costa Mesa has a wildfire risk score of 47 out of 100. Moderate wildfire risk means smoke events are possible. Having a HEPA air purifier available is recommended.

Is mold a concern in Costa Mesa?

Costa Mesa has a mold risk score of 41 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 → California → Costa Mesa, CA → Air Quality