Understanding Air Quality: Resources for Our Learning Community

Understanding Air Quality:

Resources for Our Learning Community

7/10/2026

Dear Valle Lindo School District Learning Community,

In recent weeks, we've received calls and public comments at our Board meetings from community members with questions about air quality related to the warehouse and park project in South El Monte. While decisions about the project rest with city and regional agencies rather than the school district, we want to help families who've reached out find reliable information they can review for themselves.

Because the questions we've received have centered on air quality, below are resources from the South Coast Air Quality Management District (South Coast AQMD) and the U.S. Environmental Protection Agency (EPA), the public agencies responsible for monitoring air quality and setting air quality standards.

Understanding the Air Quality Index (AQI)

Air quality is commonly reported using the Air Quality Index (AQI). A higher AQI number indicates higher measured pollution levels. The AQI uses six color-coded categories, from "Good" (green) to "Hazardous" (maroon), and accounts for pollutants such as ozone, fine particulate matter (PM2.5 and PM10), nitrogen dioxide, and carbon monoxide. An AQI value of 50 or below represents good air quality, while a value at or below 100 is generally considered satisfactory; when values rise above 100, air quality is considered unhealthy first for certain sensitive groups, and then for everyone as values climb higher.

A Quick Note on Particle Pollution (PM2.5 and PM10)

You'll often see two measures of particle pollution. PM10 refers to coarse particles (such as dust), while PM2.5 refers to fine particles that are smaller. Both are measured because they behave differently in the air and are reported separately in air quality data.

What the AQI Categories Mean for Activity

The AQI is designed to help people plan outdoor activity. When the AQI is good, conditions are fine for outdoor activity; as values rise into unhealthy ranges, people are advised to consider reducing prolonged or heavy outdoor exertion to protect their health. The EPA's AirNow site offers plain-language activity guides for each category: https://www.airnow.gov/

Who is Most Sensitive to Air Pollution

Some groups are more affected by poor air quality than others. Children, older adults, and individuals with respiratory or cardiovascular conditions such as asthma or heart disease are typically among the first groups affected when air quality is poor.

How to Check Air Quality Near You

Interactive map (regional): South Coast AQMD's current air quality map shows neighborhood-level readings at over 1,200 locations across the region: aqmd.gov/home/air-quality/current-air-quality-data
Interactive map (national): The EPA's AirNow map provides a nationally consistent view of current air quality by location: https://www.airnow.gov/
Mobile apps: Both the free South Coast AQMD app and the EPA AirNow app provide real-time AQI and forecasts (available for iOS and Android).
Air Quality Index Brochure: South Coast AQMD's brochure, available in English and Spanish, explains the categories in plain language: aqmd.gov/home/research/pubs-docs-reports/brochures

Reading the Data

Real-time readings offer a helpful general picture of current conditions, but South Coast AQMD notes that raw real-time monitor data is preliminary and subject to change until validated. Local conditions such as weather can cause readings to vary across locations and over time. For questions about what specific readings mean for your family's health, we encourage you to consult your healthcare provider.

Where to Learn More About the Project

The City of South El Monte is the lead agency for this project and maintains the official project record, including the Environmental Impact Report and related documents. Community members with questions about the project, its findings, or next steps can find information on the City's website or by contacting the City directly. The city can be contacted at (626)579-6540. Project materials are available through the City's Current Projects page: cityofsouthelmonte.org/606/Current-Projects.

We appreciate our community's engagement and are always glad to help families find factual information. If you have questions for the district, please contact us at (626) 580-0610.