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AirHistory

What Is the Air Quality in McLennan, Texas?

McLennan, Texas has an Air Quality Grade of C (fair) with a 5-year median AQI of 43. The dominant pollutant is Ground-Level Ozone, and air quality has been worsening over the past decade.

McLennan, Texas Air Quality Snapshot

Air Quality GradeC58/100
5-Year Median AQI43 (Good)
Most Recent Median AQI (2023)52 (Moderate)
Dominant PollutantGround-Level Ozone
10-Year TrendWorsening (+0.76 AQI/yr)
Unhealthy Days (last 5 yr)8
National Rank (cleanest = #1)#675 of 1,020 (66th most polluted percentile)
Texas Rank#23 of 42

What Does the C Grade Mean?

McLennan, Texas earns a C — air quality is fair, but not great. With a 5-year median AQI of 43, the city sees a meaningful number of "Moderate" days each year, when the EPA flags air as a concern for unusually sensitive people.

McLennan, Texas's 5-year median AQI of 43 is 2 points above the national average of 41 — meaningfully more polluted than the typical U.S. metro tracked here. Within Texas, McLennan, Texas's air quality is roughly typical for the state, where the average city posts a 5-year median AQI of 42.

For context within Texas: Lubbock, Texas currently holds the state's cleanest grade (B, AQI 28), while Harris, Texas sits at the bottom (D, AQI 59).

What's in McLennan, Texas's Air?

The dominant pollutant in McLennan, Texas is Ground-Level Ozone. Ground-level ozone forms when sunlight reacts with vehicle exhaust and industrial emissions. It is worst on hot, sunny, stagnant summer days. Ozone irritates the lungs, triggers asthma attacks, and reduces lung function — even healthy adults can feel chest tightness and shortness of breath after exercising in elevated ozone.

Days by Dominant Pollutant (2023)

PollutantDays as DominantShare of Year
Fine Particulate Matter (PM2.5)23865%
Ground-Level Ozone12334%
Carbon Monoxide41%

Is the Air Getting Better or Worse?

Air quality in McLennan, Texas has been getting worse over the past decade, with median AQI climbing by roughly 0.8 points per year. That bucks the national trend of broad improvement, and most often reflects either growing wildfire smoke exposure (particularly across the West) or rising local emissions from population and freight growth.

In 2014, McLennan, Texas posted a median AQI of 44. By 2023 that figure was 52 — a rise of 8 AQI points dirtier across 10 years of EPA records.

Year-by-Year AQI in McLennan, Texas

YearMedian AQIGood DaysUnhealthy DaysDominant Pollutant
2014442361PM2.5
2015422503Ozone
2016373270Ozone
2017391661Ozone
2018382480Ozone
2019393130Ozone
2020392940Ozone
2021392800Ozone
2022482090PM2.5
2023521698PM2.5

Health Context for McLennan, Texas

Across the past five years, this area has logged just 8 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 2 days per year, or roughly one every other month. That is a low count by national standards.

Healthy adults can continue normal outdoor activity in most weather, but should pay attention to AQI alerts during the worst pollution windows. People with asthma, heart disease, or pregnancy should reduce prolonged or intense outdoor exertion on flagged days, and consider running an indoor HEPA air cleaner during peak season. Because ozone peaks in the afternoon on hot sunny days, plan outdoor exercise for early morning or after sunset on bad-air days.

How This Grade Is Calculated

The AirHistory Air Quality Grade combines four signals: the 5-year median AQI (40% of the score), the 10-year trend direction (30%), the count of unhealthy days per year (20%), and the dominant pollutant type (10%). All four come directly from the EPA Air Quality System (AQS), which aggregates readings from federally certified monitors. Read the full methodology.

McLennan, Texas has an Air Quality Grade of C (fair) with a 5-year median AQI of 43. The dominant pollutant is Ground-Level Ozone, and air quality has been worsening over the past decade.

This answer pulls from the EPA Air Quality System (AQS), the authoritative federal source for U.S. air quality and pollution monitoring. The headline number above is the direct answer; what follows is the additional context most readers need to use the answer for a real decision rather than just a fact lookup.

For readers turning this answer into action: cross-reference against the underlying the EPA Air Quality System (AQS) record before acting on time-sensitive decisions. The site renders the data as it was published; subsequent revisions can shift the picture, and the live federal data is always the authoritative current reference.

Source: EPA Outdoor Air Quality Data, 2026.