EnviroNearby

Johnston County, North Carolina air quality history

Daily Air Quality Index summaries from EPA monitors in Johnston, North Carolina, 1983–2025.

78%
Good days in 2025
41
Median daily AQI, 2025
0
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Johnston, North Carolina on 365 days. 283 of those days (78%) were in the Good range, and the median daily AQI was 41. That median is about the same as the typical monitored county in North Carolina (median 39 across 33 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 243 days. Across the years with fuller monitoring, the share of Good days rose: an average of 52% in 1984–1987 versus 72% in 2023–2025.

Years with fewer than 120 monitored days (1983, 1993) are shown in the table but left out of comparisons and trend statements.

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%1983: Good 53 of 105 days1983: Moderate 28 of 105 days1983: Unhealthy for Sensitive Groups 22 of 105 days1983: Unhealthy 2 of 105 days19831984: Good 110 of 188 days1984: Moderate 52 of 188 days1984: Unhealthy for Sensitive Groups 25 of 188 days1984: Unhealthy 1 of 188 days1985: Good 121 of 190 days1985: Moderate 51 of 190 days1985: Unhealthy for Sensitive Groups 18 of 190 days1987: Good 69 of 206 days1987: Moderate 73 of 206 days1987: Unhealthy for Sensitive Groups 50 of 206 days1987: Unhealthy 13 of 206 days1987: Very Unhealthy 1 of 206 days1990: Good 115 of 211 days1990: Moderate 71 of 211 days1990: Unhealthy for Sensitive Groups 21 of 211 days1990: Unhealthy 4 of 211 days1993: Good 31 of 78 days1993: Moderate 40 of 78 days1993: Unhealthy for Sensitive Groups 7 of 78 days19931994: Good 115 of 213 days1994: Moderate 59 of 213 days1994: Unhealthy for Sensitive Groups 34 of 213 days1994: Unhealthy 5 of 213 days1995: Good 116 of 192 days1995: Moderate 49 of 192 days1995: Unhealthy for Sensitive Groups 24 of 192 days1995: Unhealthy 3 of 192 days1996: Good 103 of 202 days1996: Moderate 67 of 202 days1996: Unhealthy for Sensitive Groups 29 of 202 days1996: Unhealthy 3 of 202 days1997: Good 89 of 213 days1997: Moderate 77 of 213 days1997: Unhealthy for Sensitive Groups 36 of 213 days1997: Unhealthy 11 of 213 days1998: Good 93 of 214 days1998: Moderate 61 of 214 days1998: Unhealthy for Sensitive Groups 43 of 214 days1998: Unhealthy 16 of 214 days1998: Very Unhealthy 1 of 214 days19981999: Good 108 of 209 days1999: Moderate 59 of 209 days1999: Unhealthy for Sensitive Groups 24 of 209 days1999: Unhealthy 16 of 209 days1999: Very Unhealthy 2 of 209 days2000: Good 118 of 213 days2000: Moderate 69 of 213 days2000: Unhealthy for Sensitive Groups 24 of 213 days2000: Unhealthy 2 of 213 days2001: Good 116 of 213 days2001: Moderate 72 of 213 days2001: Unhealthy for Sensitive Groups 25 of 213 days2002: Good 100 of 212 days2002: Moderate 69 of 212 days2002: Unhealthy for Sensitive Groups 25 of 212 days2002: Unhealthy 17 of 212 days2002: Very Unhealthy 1 of 212 days2003: Good 147 of 207 days2003: Moderate 51 of 207 days2003: Unhealthy for Sensitive Groups 7 of 207 days2003: Unhealthy 2 of 207 days20032004: Good 155 of 213 days2004: Moderate 48 of 213 days2004: Unhealthy for Sensitive Groups 10 of 213 days2005: Good 122 of 213 days2005: Moderate 68 of 213 days2005: Unhealthy for Sensitive Groups 21 of 213 days2005: Unhealthy 2 of 213 days2006: Good 132 of 213 days2006: Moderate 75 of 213 days2006: Unhealthy for Sensitive Groups 6 of 213 days2007: Good 109 of 212 days2007: Moderate 86 of 212 days2007: Unhealthy for Sensitive Groups 16 of 212 days2007: Unhealthy 1 of 212 days2008: Good 133 of 214 days2008: Moderate 68 of 214 days2008: Unhealthy for Sensitive Groups 13 of 214 days20082009: Good 185 of 260 days2009: Moderate 75 of 260 days2010: Good 144 of 266 days2010: Moderate 116 of 266 days2010: Unhealthy for Sensitive Groups 6 of 266 days2011: Good 153 of 257 days2011: Moderate 97 of 257 days2011: Unhealthy for Sensitive Groups 7 of 257 days2012: Good 203 of 263 days2012: Moderate 54 of 263 days2012: Unhealthy for Sensitive Groups 5 of 263 days2012: Unhealthy 1 of 263 days2013: Good 213 of 261 days2013: Moderate 48 of 261 days20132014: Good 212 of 263 days2014: Moderate 51 of 263 days2015: Good 211 of 262 days2015: Moderate 51 of 262 days2016: Good 201 of 304 days2016: Moderate 102 of 304 days2016: Unhealthy for Sensitive Groups 1 of 304 days2017: Good 216 of 365 days2017: Moderate 149 of 365 days2018: Good 228 of 354 days2018: Moderate 126 of 354 days20182019: Good 224 of 363 days2019: Moderate 139 of 363 days2020: Good 266 of 339 days2020: Moderate 73 of 339 days2021: Good 240 of 365 days2021: Moderate 125 of 365 days2022: Good 271 of 365 days2022: Moderate 93 of 365 days2022: Unhealthy for Sensitive Groups 1 of 365 days2023: Good 240 of 365 days2023: Moderate 124 of 365 days2023: Unhealthy for Sensitive Groups 1 of 365 days20232024: Good 261 of 365 days2024: Moderate 104 of 365 days2025: Good 283 of 365 days2025: Moderate 82 of 365 days2025
  • 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 year0501001501983: 90th percentile AQI 1261984: 90th percentile AQI 1121985: 90th percentile AQI 1001987: 90th percentile AQI 1431990: 90th percentile AQI 1011993: 90th percentile AQI 1001994: 90th percentile AQI 1151995: 90th percentile AQI 1151996: 90th percentile AQI 1121997: 90th percentile AQI 1221998: 90th percentile AQI 1471999: 90th percentile AQI 1402000: 90th percentile AQI 1012001: 90th percentile AQI 1012002: 90th percentile AQI 1362003: 90th percentile AQI 872004: 90th percentile AQI 842005: 90th percentile AQI 1012006: 90th percentile AQI 842007: 90th percentile AQI 932008: 90th percentile AQI 902009: 90th percentile AQI 642010: 90th percentile AQI 742011: 90th percentile AQI 802012: 90th percentile AQI 592013: 90th percentile AQI 552014: 90th percentile AQI 572015: 90th percentile AQI 572016: 90th percentile AQI 612017: 90th percentile AQI 612018: 90th percentile AQI 592019: 90th percentile AQI 602020: 90th percentile AQI 552021: 90th percentile AQI 602022: 90th percentile AQI 552023: 90th percentile AQI 602024: 90th percentile AQI 582025: 90th percentile AQI 561983: Median AQI 501984: Median AQI 471985: Median AQI 461987: Median AQI 741990: Median AQI 491993: Median AQI 581994: Median AQI 491995: Median AQI 451996: Median AQI 501997: Median AQI 611998: Median AQI 611999: Median AQI 492000: Median AQI 502001: Median AQI 482002: Median AQI 542003: Median AQI 442004: Median AQI 412005: Median AQI 482006: Median AQI 472007: Median AQI 502008: Median AQI 452009: Median AQI 422010: Median AQI 492011: Median AQI 472012: Median AQI 422013: Median AQI 372014: Median AQI 422015: Median AQI 412016: Median AQI 442017: Median AQI 462018: Median AQI 442019: Median AQI 462020: Median AQI 392021: Median AQI 442022: Median AQI 422023: Median AQI 442024: Median AQI 432025: Median AQI 41198319931998200320082013201820232025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

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
Fine particles (PM2.5)24367%
Ozone12233%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365283820000415684PM2.5
20243652611040000435884PM2.5
202336524012410004460115PM2.5
20223652719310004255140PM2.5
20213652401250000446097PM2.5
2020339266730000395575PM2.5
20193632241390000466087PM2.5
20183542281260000445990PM2.5
20173652161490000466193PM2.5
201630420110210004461107PM2.5
2015262211510000415793Ozone
2014263212510000425784Ozone
2013261213480000375597Ozone
20122632035451004259177Ozone
20112571539770004780136Ozone
201026614411660004974119Ozone
2009260185750000426490Ozone
200821413368130004590143Ozone
200721210986161005093154Ozone
20062131327560004784126Ozone
2005213122682120048101182Ozone
200421315548100004184122Ozone
20032071475172004487164Ozone
20022121006925171054136207Ozone
2001213116722500048101147Ozone
2000213118692420050101197Ozone
19992091085924162049140203Ozone
1998214936143161061147202Ozone
1997213897736110061122182Ozone
1996202103672930050112166Ozone
1995192116492430045115164Ozone
1994213115593450049115179Ozone
1993783140700058100140Ozone
1990211115712140049101161Ozone
1987206697350131074143202Ozone
1985190121511800046100150Ozone
1984188110522510047112151Ozone
198310553282220050126159Ozone

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 2025

All monitored counties in North Carolina

Source: U.S. EPA AirData, “Annual AQI by County” files for 1983–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem