AIR QUALITY CA USG

Air Quality Alert: Sylmar, CA - 101 AQI

AQI 101 · USG · Ozone · Updated 2026-07-18

Sylmar's air quality is unhealthy for sensitive groups. People with respiratory conditions should limit outdoor activity.

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

101

Average AQI

USG

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. Sylmar's average AQI of 101 falls in the "USG" 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 Sylmar

AQI varies across Sylmar's 2 ZIP codes based on proximity to pollution sources and local geography.

ZIP Code	AQI	Category	Wildfire	Mold
91342	101	USG	90	35	View report →
91392	101	USG	90	17	View report →

Air Quality Overview

Sylmar, California has air quality rated Unhealthy for Sensitive Groups with an average AQI of 101. People with respiratory conditions, children, and older adults may experience health effects. 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 Sylmar

AQI varies across Sylmar's 2 ZIP codes based on proximity to pollution sources, traffic patterns, and local geography:

ZIP Code	AQI	Category	Wildfire Risk	Mold Score
91342	101	USG	90	35
91392	101	USG	90	17

Wildfire Smoke Risk

Sylmar has an elevated wildfire smoke risk with an average smoke risk score of 90 (scale 0-100). There have been 74 fires recorded within 100 km of city ZIP codes.

Metric	Value
Avg. smoke risk score	90
Max smoke risk score	90
Fires within 100 km	74
High-risk ZIP codes	2

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

Sylmar has an average mold risk score of 26 out of 100.

Factor	Value
Mold risk score	26/100
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 USG-level air quality (AQI 101), sensitive groups should limit outdoor exposure:

Sensitive groups: avoid prolonged outdoor exertion
General public: reduce prolonged or heavy outdoor exertion
Keep windows and doors closed
Run HEPA air purifiers continuously
Wear N95 masks outdoors if prolonged exposure is unavoidable

Sylmar vs. Nearby California Cities

How Sylmar's air quality compares to nearby cities:

City	AQI	Category	Population
Sylmar	101	USG	93,513
Richmond	46	Good	93,599
Santa Rita Park	64	Moderate	93,692
Bell Gardens	55	Moderate	93,783

ZIP Codes in Sylmar

Sylmar covers 2 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 Sylmar?

Sylmar's average AQI is 101 (USG). This level poses health risks, especially for people with respiratory conditions, children, and the elderly. Air purifiers and limiting outdoor activity on high-AQI days are recommended.

How many unhealthy air days does Sylmar have?

Sylmar experiences 28 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 Sylmar?

The average Air Quality Index (AQI) in Sylmar is 101, categorized as USG. 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 Sylmar?

Sylmar has a wildfire risk score of 90 out of 100. High wildfire risk can significantly worsen air quality during fire season. Consider HEPA air purifiers and monitor AirNow.gov for real-time conditions.

Is mold a concern in Sylmar?

Sylmar has a mold risk score of 26 out of 100, based on humidity, precipitation, and temperature data. Maintain good ventilation and address any water intrusion promptly to prevent mold growth.

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