EnviroNearby

Montgomery County, Arkansas air quality history

Daily Air Quality Index summaries from EPA monitors in Montgomery, Arkansas, 1991–2004.

96%
Good days in 2004
30
Median daily AQI, 2004
0
Days above 100 in 2004
290
Days with an AQI in 2004 (of 366)

In 2004, EPA reported a daily Air Quality Index (AQI) for Montgomery, Arkansas on 290 days. 279 of those days (96%) were in the Good range, and the median daily AQI was 30. That median is lower than the typical monitored county in Arkansas (median 43.5 across 8 counties), and lower than the typical monitored U.S. county (42). The main pollutant was ozone on 290 days. Across the years with fuller monitoring, the share of Good days fell: an average of 98% in 1991–1993 versus 92% in 2002–2004.

EPA did not report an AQI for every day of 2004 here (290 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%1991: Good 362 of 362 days19911992: Good 364 of 366 days1992: Moderate 2 of 366 days19921993: Good 341 of 362 days1993: Moderate 21 of 362 days19931994: Good 343 of 362 days1994: Moderate 19 of 362 days19941995: Good 305 of 364 days1995: Moderate 48 of 364 days1995: Unhealthy for Sensitive Groups 11 of 364 days19951996: Good 343 of 363 days1996: Moderate 20 of 363 days19961997: Good 331 of 363 days1997: Moderate 31 of 363 days1997: Unhealthy for Sensitive Groups 1 of 363 days19971998: Good 313 of 356 days1998: Moderate 38 of 356 days1998: Unhealthy for Sensitive Groups 4 of 356 days1998: Unhealthy 1 of 356 days19981999: Good 311 of 362 days1999: Moderate 43 of 362 days1999: Unhealthy for Sensitive Groups 8 of 362 days19992000: Good 300 of 352 days2000: Moderate 48 of 352 days2000: Unhealthy for Sensitive Groups 4 of 352 days20002001: Good 331 of 358 days2001: Moderate 27 of 358 days20012002: Good 320 of 365 days2002: Moderate 35 of 365 days2002: Unhealthy for Sensitive Groups 10 of 365 days20022003: Good 337 of 361 days2003: Moderate 23 of 361 days2003: Unhealthy for Sensitive Groups 1 of 361 days20032004: Good 279 of 290 days2004: Moderate 11 of 290 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 year0501001991: 90th percentile AQI 361992: 90th percentile AQI 401993: 90th percentile AQI 461994: 90th percentile AQI 461995: 90th percentile AQI 671996: 90th percentile AQI 471997: 90th percentile AQI 501998: 90th percentile AQI 581999: 90th percentile AQI 642000: 90th percentile AQI 612001: 90th percentile AQI 492002: 90th percentile AQI 582003: 90th percentile AQI 472004: 90th percentile AQI 461991: Median AQI 191992: Median AQI 281993: Median AQI 311994: Median AQI 331995: Median AQI 361996: Median AQI 341997: Median AQI 311998: Median AQI 331999: Median AQI 342000: Median AQI 342001: Median AQI 332002: Median AQI 332003: Median AQI 322004: Median AQI 3019911992199319941995199619971998199920002001200220032004
  • 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
Ozone290100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2004290279110000304693Ozone
20033613372310003247108Ozone
200236532035100003358126Ozone
2001358331270000334980Ozone
20003523004840003461119Ozone
19993623114380003464147Ozone
19983563133841003358161Ozone
19973633313110003150101Ozone
1996363343200000344793Ozone
199536430548110003667122Ozone
1994362343190000334690Ozone
1993362341210000314677Ozone
199236636420000284080Ozone
199136236200000193650Ozone

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 Arkansas

Source: U.S. EPA AirData, “Annual AQI by County” files for 1991–2004 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem