Air-quality monitor map
Enable Air quality in Layers and zoom to level 5 or closer to see available ground-monitor measurements. Choose a pollutant in the legend, then select a station for its value and source details.
The colors show raw pollutant concentrations. They do not mean good, moderate, or another air-quality index category. Different pollutants cannot be compared as if they shared one health scale. For a regional index where suitable evidence exists, use Air quality at a place.
The layer starts with PM2.5. It also supports PM10, ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, ammonia, and nitric oxide. Availability varies by source and station.
The common scale uses µg/m³, with legend stops at 0, 10, 25, 50, 75, and 100+. Values above 100 remain visible in station details even though the symbol scale is capped. Compatible mg/m³ readings are converted to µg/m³. Volume mixing ratios in ppb or ppm are excluded from this scale because conversion needs additional physical assumptions.
Reading stations
Station details show available observation and interval times, freshness, quality, station class, fixed/mobile status, completeness, estimated or gap-filled flags, provider, and data owner. Read those labels alongside the value. A nearby station can describe different conditions from your selected location.
Marker opacity reflects freshness and outlines distinguish station class. Text labels also state those properties. The map credits sources represented in the displayed station snapshot.
Loading and degraded results
The legend distinguishes loading, an empty area, stale evidence, excluded sources, failures, and truncated results. The client displays at most 2,000 markers, so a dense viewport may omit stations. Zoom in to inspect a smaller area.
A failed refresh can retain the previous markers and credits with a warning. These are older observations, not proof of current conditions. Changing the pollutant clears the previous pollutant's markers while the new selection loads. If no stations appear, check the zoom, pollutant, source coverage, and legend status before concluding that the area has no pollution.
Operators and client developers can use the air-quality monitor API reference for paging, units, limits, and response states.