Real Estate & Relocation
Air quality is a top concern for families relocating, especially those with children or respiratory conditions. ZIP-level AQI data helps agents and relocation consultants address this question with data.
Annual air quality index, good air days, and unhealthy air days mapped to every US ZIP code. Part of the EnrichZip dataset — all 33,000+ US ZIP codes, instant download.
How to use this data
Real Estate & Relocation
Air quality is a top concern for families relocating, especially those with children or respiratory conditions. ZIP-level AQI data helps agents and relocation consultants address this question with data.
Environmental Health Researchers
Analyze correlations between air quality, health outcomes, demographics, and proximity to industrial facilities using ZIP-level AQI metrics.
Corporate Site Selectors
Employee quality-of-life concerns include air quality. Employers relocating or expanding facilities increasingly consider environmental quality in location decisions.
Insurance & Healthcare
Air quality is a risk factor for respiratory and cardiovascular conditions. ZIP-level AQI data supports environmental risk modeling for health insurance and actuarial applications.
Columns Included
Source: US Environmental Protection Agency (EPA). All columns are pre-joined and ready to use — no API key or GIS software required.
| Column Name | Description |
|---|---|
epa_days_measured |
Number of days with AQI measurements in the year (county-level) |
epa_good_air_days |
Number of days with Good AQI (0-50) |
epa_unhealthy_days |
Number of days with Unhealthy AQI (151-200) |
epa_very_unhealthy_days |
Number of days with Very Unhealthy AQI (201-300) |
epa_hazardous_days |
Number of days with Hazardous AQI (301+) |
epa_median_aqi |
Median Air Quality Index for the year |
epa_90th_pct_aqi |
90th percentile AQI — represents worst 10% of days |
About This Data
Air quality has become a significant factor in real estate decisions, corporate location analysis, and public health research. The EPA Air Quality System (AQS) is the official federal repository for ambient air quality data, collecting measurements from over 4,000 monitoring sites across the country.
EPA publishes annual county-level AQI summaries — the number of good, unhealthy, and hazardous air days each year, plus median and 90th percentile AQI values. EnrichZip maps these county metrics to ZIP codes for easy integration with ZIP-level market analysis.
The most useful metrics for most applications are the median AQI (overall air quality level) and the count of unhealthy days (days where AQI exceeded 150). For real estate and relocation, the number of days per year where the air is unhealthy for everyone is a concrete, understandable metric that buyers and renters increasingly ask about.
Western ZIP codes — particularly in California, Oregon, and Washington — have seen significant increases in unhealthy air days due to wildfire smoke. ZIP codes near major industrial facilities in the Midwest and South often have elevated particulate matter. Urban cores in major metro areas face ozone challenges tied to vehicle emissions.
For environmental justice research, combining EPA air quality data with Census income and race demographics reveals persistent patterns of disproportionate pollution burden in low-income communities and communities of color — a pattern well-documented in academic literature and increasingly relevant for ESG and community impact analysis.
FAQ
The AQI is the EPA's standardized measure of air quality, calculated from concentrations of five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. AQI values range from 0 (best) to 500 (worst). Values above 100 are considered unhealthy for sensitive groups; above 150 is unhealthy for everyone.
EPA air quality monitoring is conducted at the county level — not every ZIP code has a monitor. Our data maps county-level AQI summaries to ZIP codes within each county. In large counties with varying air quality (e.g., Los Angeles), all ZIPs receive the same county-level values. This is a known limitation of the data.
EPA publishes annual AQI summary files each year. Our current dataset uses 2024 annual data, which is the most recent available. We update annually.
Not all US counties have EPA air quality monitors. Roughly 1,000 counties have monitoring data; the remaining ~2,100 counties (mostly rural) have no monitor. ZIP codes in unmonitored counties will have null values for EPA columns.