🇺🇸🇨🇦 North American Standards

US EPA & Canadian Air QualityAQI, NAAQS, and AQHI Explained

Complete guide to North American air quality regulations. Understand the EPA's AQI system, NAAQS standards, California's stricter rules, and Canada's AQHI.

Key Standards

9 μg/m³
EPA PM2.5 annual limit (2024)
35 μg/m³
EPA PM2.5 24-hour limit
8.8 μg/m³
Canada CAAQS PM2.5
106
US counties exceed limits

US EPA Air Quality Index (AQI)

The EPA's AQI is the standard measure for communicating daily air quality across the United States. It covers five major pollutants: PM2.5, PM10, ozone, NO2, SO2, and CO.

0-50
Good
Air quality is satisfactory; little or no risk.
51-100
Moderate
Acceptable; some pollutants may concern sensitive individuals.
101-150
Unhealthy for Sensitive Groups
Sensitive groups may experience effects. General public less likely.
151-200
Unhealthy
Everyone may begin to experience effects; sensitive groups more serious.
201-300
Very Unhealthy
Health alert: everyone may experience more serious effects.
301-500
Hazardous
Emergency conditions. Entire population likely affected.

NAAQS - National Ambient Air Quality Standards

NAAQS are legally binding limits set by the EPA under the Clean Air Act. Areas that don't meet these standards are designated "non-attainment" and must develop improvement plans.

PollutantPrimary StandardAveraging Time
PM2.59 μg/m³ (annual), 35 μg/m³ (24-hr)Annual mean / 24 hours
PM10150 μg/m³24 hours
Ozone (O3)0.070 ppm8 hours
NO253 ppb (annual), 100 ppb (1-hr)Annual mean / 1 hour
SO275 ppb1 hour
CO9 ppm (8-hr), 35 ppm (1-hr)8 hours / 1 hour

California - Stricter Standards

California has the authority to set stricter air quality standards than federal EPA requirements through CARB (California Air Resources Board). Many states follow California's lead.

California-Specific Rules

  • • PM2.5 annual: 12 μg/m³ (stricter than federal)
  • • Vehicle emission standards (CARB)
  • • Smog check requirements
  • • Spare the Air days with burning bans
  • • Zero-emission vehicle mandates

Problem Areas

  • • Central Valley: Worst ozone in US
  • • Los Angeles Basin: PM2.5 + ozone
  • • San Joaquin Valley: Agriculture + transport
  • • Wildfire smoke: Increasing problem
California Air Quality Deep Dive →

Canadian AQHI

Canada uses the Air Quality Health Index (AQHI), a 10+ point scale that focuses on health impact rather than just concentration levels.

1-3
Low Risk
4-6
Moderate Risk
7-10
High Risk
10+
Very High Risk

AQHI combines ground-level ozone, PM2.5, and NO2 into a single health-focused number. It's reported hourly across 170+ Canadian communities.

Key US States

California

Strictest standards in US. CARB regulations. Many cities exceed limits.

Cities: Los Angeles, San Francisco, San Diego

Texas

Houston-Galveston ozone non-attainment. Dallas-Fort Worth issues.

Cities: Houston, Dallas, Austin

New York

NYC meets most standards but PM2.5 concerns remain.

Cities: New York City, Buffalo, Albany

Pennsylvania

Pittsburgh historically polluted. Philadelphia ozone issues.

Cities: Philadelphia, Pittsburgh, Allentown

Ohio

Industrial legacy. Cleveland and Cincinnati working on improvements.

Cities: Cleveland, Columbus, Cincinnati

Canadian Provinces

Ontario

Toronto and Hamilton industrial areas. Windsor affected by Detroit.

Cities: Toronto, Ottawa, Hamilton

British Columbia

Generally good air but wildfire smoke issues increasing.

Cities: Vancouver, Victoria, Kelowna

Alberta

Oil sands impact. Calgary and Edmonton industrial emissions.

Cities: Calgary, Edmonton, Red Deer

Quebec

Montreal industrial areas. Generally good compliance.

Cities: Montreal, Quebec City, Laval

Check North American Air Quality

View real-time air quality data for US and Canadian cities. See how your area compares to EPA and AQHI standards.

North America Air Quality Hub →