Methodology

Data Collection

BreathePeek compiles air quality and pollen data from multiple authoritative sources:

• EPA Air Quality System (AQS) — Official air quality monitoring data from thousands of stations across the United States.
• AirNow — Real-time and historical AQI data provided by the EPA in partnership with state and local agencies.
• National Allergy Bureau — Pollen and mold spore counting data from certified stations.
• State Environmental Agencies — Additional monitoring data, nonattainment area designations, and trend analyses.

AQI Calculation

AQI values are calculated using the EPA's standard methodology, which maps pollutant concentrations to the 0-500 AQI scale using published breakpoints. The overall AQI for a location is the highest AQI among all measured pollutants.

City Selection

Our 73 cities were selected to provide comprehensive coverage of US metropolitan areas, including cities from all 50 states plus Washington DC. Selection prioritized population size, geographic diversity, and availability of robust monitoring data.

Pollen Data

Pollen season timing and severity are based on multi-year averages from certified pollen counting stations. Seasons are defined by the period during which pollen counts consistently exceed threshold levels for each allergen type.

Updates

We review and update our database regularly to incorporate new EPA data releases, changes in air quality standards, and updated pollen season observations.

Limitations

Our data represents averages and historical trends, not real-time conditions. Air quality varies by neighborhood, time of day, and weather conditions. Pollen counts vary annually based on weather patterns. For current conditions, we recommend checking AirNow.gov.