Knox, Nebraska Air Quality Today
AirHistory tracks long-run EPA monitoring rather than live readings, so for the live number check AirNow.gov below. As a baseline, Knox, Nebraska's most recent EPA year (2023) posted a median AQI of 41 (Good) against a 5-year median of 37 and an overall Grade of C. The dominant pollutant is Ground-Level Ozone, which tells you which days are most likely to spike.
Check Today's Live AQI in Knox, Nebraska
AirHistory is built on 10 years of EPA Air Quality System records, so it shows you what air quality in Knox, Nebraska typically looks like — not the live reading for this exact hour. For today's real-time AQI, check AirNow.gov (the EPA's official live index) or the AirNow Fire and Smoke Map during wildfire season.
That said, the history is the best predictor of a normal day. In 2023, Knox, Nebraska posted a median AQI of 41 (Good), with 271 "Good" days and 14 days that crossed into "Unhealthy for Sensitive Groups" or worse. The dominant pollutant, Ground-Level Ozone, is the one most likely to push today's number up — 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.
Knox, Nebraska Air Quality Snapshot
| Air Quality Grade | C62/100 |
| 5-Year Median AQI | 37 (Good) |
| Most Recent Median AQI (2023) | 41 (Good) |
| Dominant Pollutant | Ground-Level Ozone |
| 10-Year Trend | Worsening (+0.42 AQI/yr) |
| Unhealthy Days (last 5 yr) | 19 |
| National Rank (cleanest = #1) | #319 of 1,020 (31th cleanest percentile) |
| Nebraska Rank | #6 of 9 |
What Does the C Grade Mean?
Knox, Nebraska earns a C — air quality is fair, but not great. With a 5-year median AQI of 37, the city sees a meaningful number of "Moderate" days each year, when the EPA flags air as a concern for unusually sensitive people.
Knox, Nebraska's 5-year median AQI of 37 is 4 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within Nebraska, Knox, Nebraska runs more polluted than the state average of 30 — local sources or geography are concentrating pollution above the state's typical reading.
For context within Nebraska: Cass, Nebraska currently holds the state's cleanest grade (A, AQI 16), while Douglas, Nebraska sits at the bottom (B, AQI 43).
What's in Knox, Nebraska's Air?
The dominant pollutant in Knox, Nebraska 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)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Ground-Level Ozone | 341 | 100% |
Is the Air Getting Better or Worse?
Air quality in Knox, Nebraska has been getting worse over the past decade, with median AQI climbing by roughly 0.4 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, Knox, Nebraska posted a median AQI of 35. By 2023 that figure was 41 — a rise of 6 AQI points dirtier across 10 years of EPA records.
Year-by-Year AQI in Knox, Nebraska
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 35 | 318 | 0 | Ozone |
| 2015 | 36 | 322 | 0 | Ozone |
| 2016 | 35 | 323 | 1 | Ozone |
| 2017 | 36 | 304 | 0 | Ozone |
| 2018 | 34 | 329 | 0 | Ozone |
| 2019 | 35 | 342 | 0 | Ozone |
| 2020 | 35 | 341 | 0 | Ozone |
| 2021 | 37 | 317 | 5 | Ozone |
| 2022 | 37 | 319 | 0 | Ozone |
| 2023 | 41 | 271 | 14 | Ozone |
Health Context for Knox, Nebraska
Across the past five years, this area has logged just 19 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 4 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.
More about Knox, Nebraska
Knox, Nebraska has an Air Quality Grade of C (fair) with a 5-year median AQI of 37. The dominant pollutant is Ground-Level Ozone, and air quality has been worsening over the past decade.
The data source behind this answer is the EPA Air Quality System (AQS). Every figure on the page traces back to that source; the methodology page describes the inputs and the refresh cadence in full detail.
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.