EnviroNearby

Amherst County, Virginia air quality history

Daily Air Quality Index summaries from EPA monitors in Amherst, Virginia, 1990–1993.

48%
Good days in 1993
51
Median daily AQI, 1993
36
Days above 100 in 1993
204
Days with an AQI in 1993 (of 365)

In 1993, EPA reported a daily Air Quality Index (AQI) for Amherst, Virginia on 204 days. 98 of those days (48%) were in the Good range, and the median daily AQI was 51. That median is higher than the typical monitored county in Virginia (median 47 across 26 counties), and higher than the typical monitored U.S. county (38). The main pollutant was ozone on 204 days.

EPA did not report an AQI for every day of 1993 here (204 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

The most recent year with data for this county is 1993; EPA's files for 1994–2025 contain no row for it, which usually means its monitors stopped reporting.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%1990: Good 122 of 205 days1990: Moderate 63 of 205 days1990: Unhealthy for Sensitive Groups 19 of 205 days1990: Unhealthy 1 of 205 days19901991: Good 118 of 203 days1991: Moderate 70 of 203 days1991: Unhealthy for Sensitive Groups 14 of 203 days1991: Unhealthy 1 of 203 days19911992: Good 132 of 213 days1992: Moderate 74 of 213 days1992: Unhealthy for Sensitive Groups 6 of 213 days1992: Unhealthy 1 of 213 days19921993: Good 98 of 204 days1993: Moderate 70 of 204 days1993: Unhealthy for Sensitive Groups 33 of 204 days1993: Unhealthy 3 of 204 days1993
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501001501990: 90th percentile AQI 971991: 90th percentile AQI 931992: 90th percentile AQI 801993: 90th percentile AQI 1151990: Median AQI 471991: Median AQI 491992: Median AQI 461993: Median AQI 511990199119921993
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 1993

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Ozone204100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
199320498703330051115179Ozone
19922131327461004680151Ozone
199120311870141004993151Ozone
199020512263191004797151Ozone

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

All monitored counties in Virginia

Source: U.S. EPA AirData, “Annual AQI by County” files for 1990–1993 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem