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AirHistory

What Is the Air Quality in Forest, Wisconsin?

Forest, Wisconsin has an Air Quality Grade of C (fair) with a 5-year median AQI of 38. The dominant pollutant is Ground-Level Ozone, and air quality has been worsening over the past decade.

Forest, Wisconsin Air Quality Snapshot

Air Quality GradeC62/100
5-Year Median AQI38 (Good)
Most Recent Median AQI (2023)42 (Good)
Dominant PollutantGround-Level Ozone
10-Year TrendWorsening (+0.52 AQI/yr)
Unhealthy Days (last 5 yr)16
National Rank (cleanest = #1)#363 of 1,020 (36th cleanest percentile)
Wisconsin Rank#6 of 27

What Does the C Grade Mean?

Forest, Wisconsin earns a C — air quality is fair, but not great. With a 5-year median AQI of 38, the city sees a meaningful number of "Moderate" days each year, when the EPA flags air as a concern for unusually sensitive people.

Forest, Wisconsin's 5-year median AQI of 38 is 3 points below the national average of 41 — meaningfully cleaner than the typical U.S. metro tracked here. Within Wisconsin, Forest, Wisconsin runs cleaner than the state average of 41 — a positive signal that local conditions (terrain, wind patterns, emission sources) are working in residents' favor.

For context within Wisconsin: Fond du Lac, Wisconsin currently holds the state's cleanest grade (B, AQI 38), while Milwaukee, Wisconsin sits at the bottom (C, AQI 49).

What's in Forest, Wisconsin's Air?

The dominant pollutant in Forest, Wisconsin 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
Ground-Level Ozone20356%
Fine Particulate Matter (PM2.5)16044%

Is the Air Getting Better or Worse?

Air quality in Forest, Wisconsin 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, Forest, Wisconsin 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 Forest, Wisconsin

YearMedian AQIGood DaysUnhealthy DaysDominant Pollutant
2014363140Ozone
2015353181Ozone
2016343251Ozone
2017363270Ozone
2018383000Ozone
2019363080Ozone
2020363110Ozone
2021382824Ozone
2022373210Ozone
20234225212Ozone

Health Context for Forest, Wisconsin

Across the past five years, this area has logged just 16 days where AQI rose into the "Unhealthy for Sensitive Groups" range or worse — about 3 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.

Forest, Wisconsin has an Air Quality Grade of C (fair) with a 5-year median AQI of 38. 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.