Royal Lakes, Illinois Air Quality
Royal Lakes has a median AQI of 37, earning an air quality grade of A — excellent air quality that ranks better than 74% of US cities. Air quality has remained relatively stable over the past decade. Ground-level ozone is the primary concern, typically peaking on warm sunny days due to vehicle and industrial emissions. In 2025, Royal Lakes recorded 247 good air quality days (91% of monitored days) and 1 unhealthy days.
Population: 301 • County: Macoupin
Current AQI
Quick Facts
| Current AQI | 18 — Good |
| Air Quality Grade | A |
| Median AQI (2025) | 37 |
| vs. U.S. Cities | Better than 74% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 1 |
| 10-Year Trend | → Stable |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Royal Lakes is sourced from the Alton monitoring area, located approximately 18 miles from city center. This EPA-certified station continuously tracks ground-level ozone, the primary driver of air quality alerts in this area.
Royal Lakes typically sees its worst air quality during summer afternoons when heat and sunlight drive ground-level ozone formation from vehicle and industrial emissions. Morning readings are generally 15–25 points lower than afternoon peaks. Outdoor activity is best planned for early morning on high-ozone days.
AQI Trend (10 Years)
Air Quality Days by Year
Royal Lakes Median AQI by Year
Annual EPA air quality data for Royal Lakes — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 37 | 247 | 1 | 105 | Ozone |
| 2024 | 35 | 342 | 1 | 105 | Ozone |
| 2023 | 37 | 310 | 10 | 129 | Ozone |
| 2022 | 33 | 352 | 2 | 108 | Ozone |
| 2021 | 31 | 339 | — | 93 | Ozone |
| 2020 | 31 | 346 | — | 93 | Ozone |
| 2019 | 33 | 340 | — | 87 | Ozone |
| 2018 | 36 | 300 | 3 | 115 | Ozone |
| 2017 | 40 | 218 | — | 93 | Ozone |
| 2016 | 39 | 182 | — | 97 | Ozone |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Royal Lakes Air Quality
What is the air quality in Royal Lakes today?
The current AQI in Royal Lakes is 18, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Royal Lakes getting better or worse?
Air quality in Royal Lakes has been stable. The median AQI has dropped 2 points (from 39 in 2016 to 37 in 2025).
What is the most common air pollutant in Royal Lakes?
Ozone is the primary air pollutant in Royal Lakes, responsible for 209 days (77% of monitored days) in 2025. Ground-level ozone forms when sunlight reacts with emissions from vehicles and industry, typically peaking on hot summer afternoons.
How many unhealthy air days does Royal Lakes have per year?
In 2025, Royal Lakes recorded 91% good air quality days (247 days) out of 272 monitored days. There were 1 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 105.
What air quality grade does Royal Lakes receive?
Royal Lakes receives an air quality grade of A, placing it better than 74% of US cities. This is based on a median AQI of 37 in 2025, with 247 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 74% of US cities
Nearby Cities
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National Rankings
See how Royal Lakes compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Royal Lakes
Royal Lakes has a summer ozone problem — hot afternoons push AQI into Moderate or higher as sunlight converts vehicle and industrial emissions into ground-level ozone. Activated carbon and PECO filters chemically neutralize ozone rather than just trapping particles.
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