EnviroNearby

Randolph County, North Carolina air quality history

Daily Air Quality Index summaries from EPA monitors in Randolph, North Carolina, 2001–2004.

70%
Good days in 2004
43
Median daily AQI, 2004
13
Days above 100 in 2004
214
Days with an AQI in 2004 (of 366)

In 2004, EPA reported a daily Air Quality Index (AQI) for Randolph, North Carolina on 214 days. 149 of those days (70%) were in the Good range, and the median daily AQI was 43. That median is lower than the typical monitored county in North Carolina (median 46 across 44 counties), and about the same as the typical monitored U.S. county (42). The main pollutant was ozone on 214 days.

EPA did not report an AQI for every day of 2004 here (214 of 366 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 2004; EPA's files for 2005–2025 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%2001: Good 98 of 214 days2001: Moderate 81 of 214 days2001: Unhealthy for Sensitive Groups 32 of 214 days2001: Unhealthy 3 of 214 days20012002: Good 120 of 214 days2002: Moderate 57 of 214 days2002: Unhealthy for Sensitive Groups 29 of 214 days2002: Unhealthy 8 of 214 days20022003: Good 147 of 211 days2003: Moderate 52 of 211 days2003: Unhealthy for Sensitive Groups 10 of 211 days2003: Unhealthy 2 of 211 days20032004: Good 149 of 214 days2004: Moderate 52 of 214 days2004: Unhealthy for Sensitive Groups 13 of 214 days2004
  • 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 year0501001502001: 90th percentile AQI 1122002: 90th percentile AQI 1222003: 90th percentile AQI 872004: 90th percentile AQI 842001: Median AQI 542002: Median AQI 492003: Median AQI 432004: Median AQI 432001200220032004
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2004

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
Ozone214100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
200421414952130004384150Ozone
200321114752102004387190Ozone
2002214120572980049122179Ozone
200121498813230054112179Ozone

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.

Counties in North Carolina with a similar median AQI in 2004

All monitored counties in North Carolina

Source: U.S. EPA AirData, “Annual AQI by County” files for 2001–2004 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem