EnviroNearby

Houston County, Alabama air quality history

Daily Air Quality Index summaries from EPA monitors in Houston, Alabama, 1989–2019.

82%
Good days in 2019
38
Median daily AQI, 2019
0
Days above 100 in 2019
280
Days with an AQI in 2019 (of 365)

In 2019, EPA reported a daily Air Quality Index (AQI) for Houston, Alabama on 280 days. 230 of those days (82%) were in the Good range, and the median daily AQI was 38. That median is lower than the typical monitored county in Alabama (median 42 across 15 counties), and lower than the typical monitored U.S. county (41). The main pollutant was ozone on 181 days. Across the years with fuller monitoring, the share of Good days rose: an average of 56% in 2005–2007 versus 83% in 2017–2019.

EPA did not report an AQI for every day of 2019 here (280 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 2019; EPA's files for 2020–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1999, 2000, 2001, 2002, 2003, 2004…) 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%1989: Good 39 of 39 days19891990: Good 48 of 55 days1990: Moderate 7 of 55 days1991: Good 53 of 57 days1991: Moderate 4 of 57 days1992: Good 55 of 57 days1992: Moderate 2 of 57 days1993: Good 55 of 57 days1993: Moderate 2 of 57 days1994: Good 53 of 56 days1994: Moderate 3 of 56 days19941995: Good 51 of 54 days1995: Moderate 3 of 54 days1996: Good 50 of 51 days1996: Moderate 1 of 51 days1997: Good 56 of 57 days1997: Moderate 1 of 57 days1998: Good 49 of 51 days1998: Moderate 2 of 51 days1999: Good 9 of 74 days1999: Moderate 62 of 74 days1999: Unhealthy for Sensitive Groups 3 of 74 days19992000: Good 28 of 102 days2000: Moderate 73 of 102 days2000: Unhealthy for Sensitive Groups 1 of 102 days2001: Good 35 of 114 days2001: Moderate 79 of 114 days2002: Good 30 of 111 days2002: Moderate 81 of 111 days2003: Good 32 of 94 days2003: Moderate 61 of 94 days2003: Unhealthy for Sensitive Groups 1 of 94 days2004: Good 21 of 73 days2004: Moderate 51 of 73 days2004: Unhealthy for Sensitive Groups 1 of 73 days20042005: Good 158 of 265 days2005: Moderate 105 of 265 days2005: Unhealthy for Sensitive Groups 2 of 265 days2006: Good 152 of 285 days2006: Moderate 127 of 285 days2006: Unhealthy for Sensitive Groups 6 of 285 days2007: Good 150 of 276 days2007: Moderate 118 of 276 days2007: Unhealthy for Sensitive Groups 7 of 276 days2007: Unhealthy 1 of 276 days2008: Good 182 of 277 days2008: Moderate 95 of 277 days2009: Good 219 of 315 days2009: Moderate 96 of 315 days20092010: Good 125 of 357 days2010: Moderate 228 of 357 days2010: Unhealthy for Sensitive Groups 4 of 357 days2011: Good 181 of 283 days2011: Moderate 102 of 283 days2012: Good 210 of 284 days2012: Moderate 74 of 284 days2013: Good 238 of 285 days2013: Moderate 47 of 285 days2014: Good 227 of 279 days2014: Moderate 52 of 279 days20142015: Good 241 of 283 days2015: Moderate 42 of 283 days2016: Good 242 of 280 days2016: Moderate 38 of 280 days2017: Good 237 of 281 days2017: Moderate 43 of 281 days2017: Unhealthy for Sensitive Groups 1 of 281 days2018: Good 230 of 277 days2018: Moderate 47 of 277 days2019: Good 230 of 280 days2019: Moderate 50 of 280 days2019
  • 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 year0501001989: 90th percentile AQI 391990: 90th percentile AQI 551991: 90th percentile AQI 411992: 90th percentile AQI 401993: 90th percentile AQI 481994: 90th percentile AQI 441995: 90th percentile AQI 431996: 90th percentile AQI 331997: 90th percentile AQI 421998: 90th percentile AQI 381999: 90th percentile AQI 932000: 90th percentile AQI 822001: 90th percentile AQI 792002: 90th percentile AQI 732003: 90th percentile AQI 722004: 90th percentile AQI 722005: 90th percentile AQI 712006: 90th percentile AQI 772007: 90th percentile AQI 772008: 90th percentile AQI 632009: 90th percentile AQI 592010: 90th percentile AQI 712011: 90th percentile AQI 672012: 90th percentile AQI 602013: 90th percentile AQI 552014: 90th percentile AQI 572015: 90th percentile AQI 542016: 90th percentile AQI 522017: 90th percentile AQI 542018: 90th percentile AQI 542019: 90th percentile AQI 551989: Median AQI 241990: Median AQI 241991: Median AQI 231992: Median AQI 201993: Median AQI 211994: Median AQI 221995: Median AQI 241996: Median AQI 171997: Median AQI 221998: Median AQI 261999: Median AQI 682000: Median AQI 602001: Median AQI 572002: Median AQI 562003: Median AQI 552004: Median AQI 572005: Median AQI 472006: Median AQI 492007: Median AQI 492008: Median AQI 442009: Median AQI 412010: Median AQI 552011: Median AQI 462012: Median AQI 402013: Median AQI 392014: Median AQI 412015: Median AQI 362016: Median AQI 372017: Median AQI 372018: Median AQI 372019: Median AQI 381989199419992004200920142019
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2019

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
Ozone18165%
Fine particles (PM2.5)9935%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2019280230500000385577Ozone
2018277230470000375480Ozone
20172812374310003754131Ozone
2016280242380000375297Ozone
2015283241420000365474Ozone
2014279227520000415780Ozone
2013285238470000395584Ozone
2012284210740000406097Ozone
201128318110200004667100Ozone
201035712522840005571115PM2.5
2009315219960000415988Ozone
2008277182950000446390Ozone
200727615011871004977161Ozone
200628515212760004977126Ozone
200526515810520004771124Ozone
200473215110005772126PM2.5
200394326110005572144PM2.5
200211130810000567385PM2.5
200111435790000577992PM2.5
2000102287310006082120PM2.5
19997496230006893144PM2.5
1998514920000263854PM10
1997575610000224252PM10
1996515010000173356PM10
1995545130000244352PM10
1994565330000224472PM10
1993575520000214855PM10
1992575520000204058PM10
1991575340000234157PM10
1990554870000245564PM10
1989393900000243950PM10

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 Alabama with a similar median AQI in 2019

All monitored counties in Alabama

Source: U.S. EPA AirData, “Annual AQI by County” files for 1989–2019 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem