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

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. Billings's average AQI of 75 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: Billings, MT

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 Billings

AQI varies across Billings's 14 ZIP codes based on proximity to pollution sources and local geography.

ZIP Code	AQI	Category	Wildfire	Mold
59101	75	Moderate	34	47	View report →
59102	75	Moderate	34	41	View report →
59103	75	Moderate	34	29	View report →
59104	75	Moderate	34	25	View report →
59105	75	Moderate	35	37	View report →
59106	75	Moderate	34	25	View report →
59107	75	Moderate	35	29	View report →
59108	75	Moderate	34	29	View report →
59111	75	Moderate	34	29	View report →
59112	75	Moderate	34	29	View report →
59114	75	Moderate	34	29	View report →
59115	75	Moderate	34	29	View report →
59116	75	Moderate	34	29	View report →
59117	75	Moderate	34	29	View report →

Air Quality Overview

Billings, Montana has moderate air quality with an average AQI of 75. 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 PM2.5.

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: PM2.5

PM2.5 (fine particulate matter) consists of particles smaller than 2.5 micrometers - about 30 times thinner than a human hair. These particles can penetrate deep into the lungs and enter the bloodstream.

Health effects of PM2.5 exposure:

• Short-term: coughing, shortness of breath, aggravated asthma
• Long-term: reduced lung function, cardiovascular disease, premature death
• Most vulnerable: children, elderly, people with heart or lung disease

Common sources in urban areas: vehicle exhaust, construction dust, industrial emissions, wildfire smoke, residential wood burning.

Air Quality by ZIP Code in Billings

AQI varies across Billings's 14 ZIP codes based on proximity to pollution sources, traffic patterns, and local geography:

Wildfire Smoke Risk

Billings has an elevated wildfire smoke risk with an average smoke risk score of 34 (scale 0-100). There have been 539 fires recorded within 100 km of city ZIP codes.

Metric	Value
Avg. smoke risk score	34
Max smoke risk score	35
Fires within 100 km	539
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

Billings has an average mold risk score of 31 out of 100.

Factor	Value
Mold risk score	31/100
Average humidity	54% 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 75), 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

Billings vs. Nearby Montana Cities

How Billings's air quality compares to nearby cities:

ZIP Codes in Billings

Billings covers 14 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.