South El Monte, California Air Quality
South El Monte has a median AQI of 77, earning an air quality grade of D — below-average air quality that ranks better than 1% 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, South El Monte recorded 30 good air quality days (11% of monitored days) and 88 unhealthy days.
Population: 19,287 • County: Los Angeles
Current AQI
Quick Facts
| Current AQI | 59 — Moderate |
| Air Quality Grade | D |
| Median AQI (2025) | 77 |
| vs. U.S. Cities | Better than 1% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 88 |
| 10-Year Trend | → Stable |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is acceptable. However, there may be a risk for some people who are unusually sensitive to air pollution.
Unusually sensitive people should consider reducing prolonged or heavy outdoor exertion.
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for South El Monte is sourced from the Los Angeles - N. Main Street monitoring area, located approximately 10 miles from city center. This EPA-certified station continuously tracks ground-level ozone, the primary driver of air quality alerts in this area.
Wildfire smoke is a significant factor in South El Monte's air quality, with regional fires capable of pushing AQI from Good to Unhealthy within hours during fire season (typically July through October). On smoke-impacted days, staying indoors with windows closed and running an air purifier with a HEPA filter is the most effective protection.
AQI Trend (10 Years)
Air Quality Days by Year
South El Monte Median AQI by Year
Annual EPA air quality data for South El Monte — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 77 | 30 | 89 | 201 | Ozone |
| 2024 | 80 | 38 | 133 | 230 | Ozone |
| 2023 | 67 | 41 | 87 | 210 | PM2.5 |
| 2022 | 74 | 17 | 94 | 209 | Ozone |
| 2021 | 79 | 9 | 97 | 281 | PM2.5 |
| 2020 | 85 | 35 | 137 | 250 | Ozone |
| 2019 | 72 | 34 | 86 | 201 | PM2.5 |
| 2018 | 78 | 7 | 108 | 201 | PM2.5 |
| 2017 | 79 | 9 | 119 | 224 | PM2.5 |
| 2016 | 77 | 7 | 104 | 226 | PM2.5 |
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 South El Monte Air Quality
What is the air quality in South El Monte today?
The current AQI in South El Monte is 59, rated "Moderate". Air quality is moderate — unusually sensitive individuals may want to limit prolonged outdoor exertion. Air quality is acceptable. However, there may be a risk for some people who are unusually sensitive to air pollution.
Is air quality in South El Monte getting better or worse?
Air quality in South El Monte has been stable. The median AQI has remained stable at around 77 over the past decade.
What is the most common air pollutant in South El Monte?
Ozone is the primary air pollutant in South El Monte, responsible for 172 days (63% 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 South El Monte have per year?
In 2025, South El Monte recorded 11% good air quality days (30 days) out of 274 monitored days. There were 59 Unhealthy for Sensitive Groups days and 29 Unhealthy days (AQI above 100). The most severe category (Very Unhealthy or Hazardous) occurred on 1 day. The highest single-day AQI recorded was 201.
What air quality grade does South El Monte receive?
South El Monte receives an air quality grade of D, placing it better than 1% of US cities. This is based on a median AQI of 77 in 2025, with 30 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 1% of US cities
Nearby Cities
Protect Your Health
With a median AQI of 77, indoor air purification is recommended
See Recommended Purifiers ↓Get AQI Alerts
Receive notifications when air quality changes in South El Monte
National Rankings
See how South El Monte compares to every other US city by air quality.
Most Polluted Cities →All city rankingsRecommended Air Purifiers for South El Monte
Ozone is South El Monte's primary pollutant. Standard HEPA filters don't capture ozone molecules — you need activated carbon or PECO technology to chemically break them down. We highlight those units here.
Blueair Blue Pure 211+
High performance for large rooms with simple operation.
- ✓Good room size match
- ✓Recommended for your air quality
- ✓High performance
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Other Great Options
Honeywell HPA300
Powerful workhorse for large rooms. Built to last.
Molekule Air Pro
Commercial-grade with patented PECO technology for destroying pollutants.
RabbitAir MinusA2
Stylish wall-mountable design with customizable artwork panels.
Not sure which air purifier is right for you?
Learn more about different types of air purifiers and how to choose the best one for your needs.
Read our complete buying guide →