Is the Air Quality Good in Columbia, Washington?
Mostly — air quality in Columbia, Washington is fair, not pristine. The city earns a Grade of C (fair) on a 5-year median AQI of 32 (Good), with 23 unhealthy-air days over five years (about 5 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 Columbia, Washington?
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 PM2.5 penetrates deep into the lungs and bloodstream, an N95 or KN95 mask provides meaningful protection on smoky or high-particulate days — surgical masks do not.
Across the past five years, this area has logged just 23 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 5 days per year, or roughly one every other month. That is a low count by national standards.
Columbia, Washington Air Quality Snapshot
| Air Quality Grade | C51/100 |
| 5-Year Median AQI | 32 (Good) |
| Most Recent Median AQI (2023) | 39 (Good) |
| Dominant Pollutant | Fine Particulate Matter (PM2.5) |
| 10-Year Trend | Worsening (+2.18 AQI/yr) |
| Unhealthy Days (last 5 yr) | 23 |
| National Rank (cleanest = #1) | #149 of 1,020 (15th cleanest percentile) |
| Washington Rank | #19 of 30 |
What Does the C Grade Mean?
Columbia, Washington earns a C — air quality is fair, but not great. With a 5-year median AQI of 32, the city sees a meaningful number of "Moderate" days each year, when the EPA flags air as a concern for unusually sensitive people.
Columbia, Washington's 5-year median AQI of 32 is 9 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within Washington, Columbia, Washington's air quality is roughly typical for the state, where the average city posts a 5-year median AQI of 31.
For context within Washington: Garfield, Washington currently holds the state's cleanest grade (A, AQI 20), while Asotin, Washington sits at the bottom (D, AQI 43).
What's in Columbia, Washington's Air?
The dominant pollutant in Columbia, Washington is Fine Particulate Matter (PM2.5). Fine particulate matter — particles less than 2.5 micrometers across — comes mostly from combustion: vehicle exhaust, wildfire smoke, residential wood burning, and industrial emissions. Because these particles are small enough to enter the bloodstream, PM2.5 is the pollutant most strongly linked to cardiovascular disease, respiratory illness, and premature death.
Days by Dominant Pollutant (2023)
| Pollutant | Days as Dominant | Share of Year |
|---|---|---|
| Ground-Level Ozone | 256 | 70% |
| Fine Particulate Matter (PM2.5) | 109 | 30% |
Is the Air Getting Better or Worse?
Air quality in Columbia, Washington has been getting worse over the past decade, with median AQI climbing by roughly 2.2 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, Columbia, Washington posted a median AQI of 22. By 2023 that figure was 39 — a rise of 17 AQI points dirtier across 10 years of EPA records.
Year-by-Year AQI in Columbia, Washington
| Year | Median AQI | Good Days | Unhealthy Days | Dominant Pollutant |
|---|---|---|---|---|
| 2014 | 22 | 315 | 0 | PM2.5 |
| 2015 | 19 | 342 | 1 | PM2.5 |
| 2016 | 20 | 318 | 0 | PM2.5 |
| 2017 | 28 | 249 | 9 | PM2.5 |
| 2018 | 22 | 250 | 7 | PM2.5 |
| 2019 | 22 | 322 | 0 | PM2.5 |
| 2020 | 23 | 323 | 8 | PM2.5 |
| 2021 | 39 | 304 | 8 | Ozone |
| 2022 | 37 | 314 | 4 | Ozone |
| 2023 | 39 | 319 | 3 | 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 Columbia, Washington
Columbia, Washington has an Air Quality Grade of C (fair) with a 5-year median AQI of 32. The dominant pollutant is Fine Particulate Matter (PM2.5), 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.