Plain-English explainers for every metric we surface.

Large industrial-scale animal agriculture facilities (typically 1,000+ cattle equivalents).

EPA's record of every public water system's compliance with Safe Drinking Water Act standards, including violation history for contaminants like nitrates, lead, arsenic, and disinfection byproducts.

An EPA tool that combines environmental indicators (air quality, hazardous waste, traffic, lead paint risk) with demographic indicators to identify communities facing disproportionate environmental burden.

An EPA-maintained record of every reportable industrial release of toxic chemicals into the air, water, or soil, reported annually by the facilities themselves.

The probability of a property in a county being damaged by flooding over the next 30 years, accounting for both FEMA flood zones and climate-adjusted projections.

How often and how severely a county is exposed to dangerously hot temperatures.

A proxy for childhood lead exposure risk based on the share of housing built before 1978, when residential lead paint was banned.

A gas that forms when sunlight reacts with pollution from cars, power plants, and industrial sources.

The total pounds of pesticide active ingredient applied to agricultural land in a county per year, including herbicides, insecticides, and fungicides.

A family of thousands of human-made chemicals (sometimes called 'forever chemicals') used in non-stick cookware, firefighting foam, water-repellent fabrics, and industrial processes.

Tiny pollution particles in the air, small enough to be inhaled deep into the lungs and to cross from the lungs into the bloodstream.

A naturally occurring radioactive gas released from uranium in soil and rock.

The fraction of a county's fine particulate matter exposure that comes specifically from wildfire smoke.

HHS's dataset on how many Medicare beneficiaries in a given area rely on electricity-powered medical equipment at home (oxygen concentrators, ventilators, kidney dialysis, etc.).

A federal designation by HRSA identifying geographic areas, populations, or facilities with too few primary care, dental, or mental health providers to meet the population's need.

CDC's small-area estimates of chronic disease prevalence, health outcomes, prevention, and risk factors at the county, place, and Census-tract level.

CDC's online query system for mortality data — every death in the U.S. by underlying cause, age, sex, race, geography, and year. The authoritative source for U.S. mortality statistics.

The Census Bureau's rolling demographic and socioeconomic survey covering every county and Census tract.

CMS's master directory of every healthcare provider with a National Provider Identifier (NPI).

A named, weighted combination of an environmental exposure and a population that is more vulnerable to that exposure.

A pattern where a county scores worse than 70% of U.S. counties on multiple major health-risk dimensions at the same time: environmental exposure, chronic disease, healthcare access, and social and economic conditions.

Where a county's score falls compared to every other U.S. county on the same measure. A score in the 80th percentile means the county is worse than 80% of U.S. counties on that measure (when the measure is one where higher = worse).