Is the Air Quality Good in Brookings, South Dakota?
Mostly — air quality in Brookings, South Dakota is fair, not pristine. The city earns a Grade of C (fair) on a 5-year median AQI of 40 (Good), with 20 unhealthy-air days over five years (about 4 per year). Healthy adults are fine most of the time, but sensitive groups should watch the daily forecast.
Who Can Safely Breathe the Air in Brookings, South Dakota?
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.
Across the past five years, this area has logged just 20 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.
Brookings, South Dakota Air Quality Snapshot
| Air Quality Grade | C61/100 |
| 5-Year Median AQI | 40 (Good) |
| Most Recent Median AQI (2023) | 42 (Good) |
| Dominant Pollutant | Ground-Level Ozone |
| 10-Year Trend | Worsening (+0.45 AQI/yr) |
| Unhealthy Days (last 5 yr) | 20 |
| National Rank (cleanest = #1) | #467 of 1,020 (46th cleanest percentile) |
| South Dakota Rank | #7 of 10 |
What Does the C Grade Mean?
Brookings, South Dakota earns a C — air quality is fair, but not great. With a 5-year median AQI of 40, the city sees a meaningful number of "Moderate" days each year, when the EPA flags air as a concern for unusually sensitive people.
Brookings, South Dakota's 5-year median AQI of 40 is right around the national average of 41 across the 1,020 monitored U.S. cities tracked here. Within South Dakota, Brookings, South Dakota runs more polluted than the state average of 36 — local sources or geography are concentrating pollution above the state's typical reading.
For context within South Dakota: Hughes, South Dakota currently holds the state's cleanest grade (A, AQI 13), while Codington, South Dakota sits at the bottom (D, AQI 40).
What's in Brookings, South Dakota's Air?
The dominant pollutant in Brookings, South Dakota 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 | 241 | 66% |
| Fine Particulate Matter (PM2.5) | 83 | 23% |
| Coarse Particulate Matter (PM10) | 41 | 11% |
Is the Air Getting Better or Worse?
Air quality in Brookings, South Dakota has been getting worse over the past decade, with median AQI climbing by roughly 0.5 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, Brookings, South Dakota posted a median AQI of 36. By 2023 that figure was 42 — a rise of 6 AQI points dirtier across 10 years of EPA records.
Year-by-Year AQI in Brookings, South Dakota
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 36 | 308 | 1 | Ozone |
| 2015 | 38 | 282 | 2 | Ozone |
| 2016 | 35 | 329 | 1 | Ozone |
| 2017 | 36 | 311 | 0 | Ozone |
| 2018 | 38 | 297 | 1 | Ozone |
| 2019 | 43 | 273 | 5 | Ozone |
| 2020 | 39 | 305 | 0 | Ozone |
| 2021 | 39 | 270 | 8 | Ozone |
| 2022 | 36 | 320 | 0 | Ozone |
| 2023 | 42 | 274 | 7 | Ozone |
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 Brookings, South Dakota
Brookings, South Dakota has an Air Quality Grade of C (fair) with a 5-year median AQI of 40. 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.