Greater Los Angeles ozone climatology
Los Angeles Smog Heat Map
Compare how often ground-level ozone reaches elevated AQI levels across the coast, basin, valleys, and Inland Empire. The map summarizes EPA regulatory observations from 2016–2025 on a 5 km comparison grid.
Map measure
AQI 51+ is Moderate. AQI 101+ is Unhealthy for Sensitive Groups. Map colors are relative within the selected measure.
Los Angeles ozone FAQ
Common questions about smog and ozone in Greater Los Angeles
When is smog season in Los Angeles?
Ground-level ozone is usually highest from late spring through early fall. Strong sunlight drives ozone chemistry, while inland heat and stagnant air can let pollution accumulate during the afternoon.
Why is ozone often worse inland than at the beach?
Sea breezes can carry ozone-forming pollution inland. As the air moves east it has more time to react in sunlight, and mountains can slow its escape. Coastal locations often stay cooler and receive cleaner marine air sooner.
Does every colored square contain an ozone monitor?
No. EPA regulatory monitors are irregularly spaced. The map estimates a continuous 5 km comparison surface from the six nearest qualifying monitors and shows the nearest monitor in the map tooltip.
What does “unhealthy for sensitive groups” mean?
An ozone AQI of 101 or higher is unhealthy for sensitive groups, including children, older adults, people with asthma, and people who are active outdoors. Follow current AirNow or South Coast AQMD guidance when air quality is elevated.
Is this map today’s air quality?
No. It summarizes typical ozone patterns from 2016 through 2025. Use the smog forecast for modeled conditions during the next three days, and AirNow for current regulatory readings and health guidance.