About the Mojave Desert's Air Quality

The Mojave Desert is known for its clear blue skies, scenic vistas, and dark night skies, and is not often associated with the heavy smog commonly seen in the South Coast Air Basin (SCAB), which includes the Los Angeles region and the Inland Empire.  However, the High Desert’s proximity to the SCAB and prevailing southwest winds can transport pollutants from more densely populated urban areas south of the Cajon Pass into our region, contributing to local air quality challenges.

Ground-level ozone remains one of the District’s primary air quality concerns, particularly during the warmer summer months.  Elevated particulate matter, including PM₁₀ and PM₂.₅, can also affect air quality, especially during high-wind events, wildfire smoke impacts, and colder seasons when stagnant conditions occur.

To understand why air quality management is important, it helps to understand how air pollution is measured.  Based on potential health and environmental impacts, certain substances are classified as pollutants under state and federal law.  Air monitoring measures the concentration of these pollutants in outdoor air.  When pollutant levels exceed established health-based standards, the area may be classified as nonattainment, and regulatory agencies are required to develop plans and programs to improve air quality.

Air quality throughout the Mojave Desert has improved significantly over time due to cleaner technologies, stronger emission controls, and coordinated efforts by industry, businesses, and regulatory agencies both within MDAQMD and neighboring regions.  Continued progress depends on maintaining these efforts and working toward achieving state and federal air quality standards for the health and benefit of all residents within the District.

Understanding Air Quality Terms

Air quality information often uses technical terms that can be confusing at first.  Words like standards, attainment, nonattainment, designations, and Air Quality Index (AQI) each have different meanings, and understanding these terms helps explain how air quality is measured and managed.

Air quality standards are health-based limits set by the U.S. Environmental Protection Agency (USEPA) and the California Air Resources Board (CARB) for pollutants in outdoor air.  Area designations describe whether a region meets those standards, while attainment status reflects the current regulatory classification for a specific pollutant.

The Air Quality Index (AQI) is different - it shows short-term daily air quality conditions and helps the public understand whether the air is healthy to breathe today. An area can have good AQI on a given day and still be classified as nonattainment based on long-term air quality data collected over several years.

Understanding these terms also helps explain why MDAQMD may regulate stationary sources such as factories and power plants, while mobile sources such as cars and trucks - often the largest contributors to pollution - are primarily regulated by state and federal agencies.

Explore this section to learn how air quality standards are set, how attainment is determined, and what these designations mean for the Mojave Desert region.  More.

Current Air Quality Conditions and Forecasts

Want to learn more about air quality in your area?  You can view current air quality conditions by checking the Air Quality Index (AQI) for the monitoring location closest to you on the MDAQMD home page.  Scroll to the “Current Air Quality” section and select the monitoring station nearest your community from the drop-down menu above the AQI color bar.

MDAQMD also issues a daily air quality forecast at noon for the following day. Forecasts for both today and tomorrow are available on the home page and through the Air Quality Map, allowing you to view conditions in or near your city.

You can also sign up to receive daily air quality forecasts by email, text message, or X (formerly Twitter) through EnviroFlash.

Current smoke and health advisories, along with information on how to protect your health during poor air quality events, are also available through MDAQMD. 

Visit AirNow to learn about the Air Quality Index (AQI), understand the AQI color categories, and view current local air quality conditions.

Community Air Monitoring with PurpleAir

In addition to MDAQMD’s regulatory air monitoring stations, residents can also view neighborhood-level air quality conditions through the District’s PurpleAir community sensor network.

PurpleAir sensors are low-cost, real-time particulate matter (PM₂.₅) monitors located throughout the Mojave Desert region.  These sensors help provide additional visibility into local air quality conditions, especially during wildfire smoke events, windblown dust, and other short-term air quality impacts.

Unlike MDAQMD’s regulatory monitoring stations, PurpleAir sensors are not used for Federal or State compliance determinations.  Instead, they provide helpful supplemental information that allows residents to better understand air quality conditions closer to home.

To explore local PurpleAir sensor data and community monitoring locations, visit the PurpleAir Community Monitor Map.  More.

Air Quality Standards

Air quality standards are established to protect public health, including sensitive groups such as children, older adults, and individuals with respiratory or heart conditions.  These standards define the maximum allowable concentration of a pollutant in outdoor air that can be present without causing adverse health effects.

Both the California Air Resources Board (CARB) and the U.S. Environmental Protection Agency (EPA) are authorized to establish ambient air quality standards.  California standards are often more stringent than federal standards and are designed to provide additional public health protection.

For information on current state and federal air quality standards, attainment designations, and area classifications, please visit the California Air Resources Board.

Attainment Status

On October 1, 2015, the U.S. Environmental Protection Agency (EPA) strengthened the federal 8-hour ozone National Ambient Air Quality Standard (NAAQS) by lowering the standard from 0.075 parts per million (ppm) to 0.070 ppm (70 parts per billion).  Based on ambient air monitoring data, a portion of the MDAQMD, known as the Federal Ozone Nonattainment Area (FONA), is designated nonattainment for the 2015 ozone standard.  More...

Exceptional Events

Exceptional events are unusual or naturally occurring events that can affect air quality but are not reasonably controllable or preventable by air agencies.  Because these events are outside normal regulatory control, they may be excluded from certain air quality planning and compliance determinations under the National Ambient Air Quality Standards (NAAQS).  Examples of exceptional events include wildfires, stratospheric ozone intrusions, and volcanic or seismic activity. 

In the Mojave Desert region, wildfire smoke and high wind dust events are among the most common exceptional events affecting air quality.  More...

Monitoring Info

Five air monitoring stations are located throughout the District in Barstow, Hesperia, Lucerne Valley, Trona, and Victorville.  These stations collect ambient air quality data 24 hours a day, seven days a week, measuring pollutants such as ozone (O₃), particulate matter (PM₁₀ and PM₂.₅), nitrogen oxides (NOₓ), and hydrogen sulfide (H₂S).  Not all monitoring stations measure every pollutant.  To see which pollutants are monitored at each location, please view our listing of monitoring stations. More...

Pollution Sources

Air pollution in the MDAQMD comes from many different sources, including large industrial facilities, power plants, motor vehicles, landscaping equipment, household activities, windblown dust, and wildfire smoke.

MDAQMD’s regulatory authority primarily applies to stationary sources of air pollution, such as industrial facilities, manufacturing operations, power generation, and other fixed-location emission sources.  Mobile sources, including cars, trucks, trains, aircraft, and most off-road equipment, are primarily regulated by state and federal agencies such as the California Air Resources Board (CARB) and the U.S. Environmental Protection Agency (USEPA).

Although mobile sources remain among the largest contributors to regional air pollution, natural sources such as windblown dust and wildfire smoke can also significantly affect air quality in the Mojave Desert region.  More...

Air Quality and Health

The air we breathe directly impacts our health.  Poor air quality can affect everyone, but some groups are more vulnerable, including children, older adults, and individuals with respiratory or cardiovascular conditions such as asthma, chronic obstructive pulmonary disease (COPD), and heart disease.

Air pollutants such as ozone, particulate matter, and other airborne contaminants can cause both short- and long-term health effects.  Depending on the type of pollutant, concentration, and duration of exposure, health impacts may range from temporary irritation and breathing difficulties to more serious chronic health conditions.  More...

What You Can Do for Clean Air