Use the nearest relevant station
PM2.5, PM10 and AQI can differ across the same province. Keep the station name, coordinates and timestamp with every value; a citywide label can hide a distant or differently situated monitor.
Thailand air-quality APIs and station data
Start with Air4Thai for official Pollution Control Department readings by monitoring station. OpenAQ can make cross-country API access easier, but its Thailand records still depend on upstream stations and should retain their original location and observation time.
Official readings and API convenience
Air4Thai is the primary Thai public source. OpenAQ is useful for normalized API access and historical analysis, but it does not turn partial station coverage into complete national coverage.
Missing or stale data is unresolved
A blank feed, old timestamp or unavailable station does not mean clean air. For a current travel decision, check the latest station observation and relevant health guidance rather than filling a gap with a provincial average.