These are American colours on a Malaysian number. The value is the DOE's Air Pollutant Index, published unchanged. The bands painted over it are the US EPA's. The two scales use different breakpoints, and Malaysia has no “Unhealthy for Sensitive Groups” tier at all — so a station reading 116 is orange here and plain “Unhealthy” on the government portal. Neither is wrong; they are different instruments.
Marker height and size both rise with severity, and every marker carries its number, because the EPA's orange and red are close enough to be indistinguishable to a red–green colourblind reader. Colour is never the only signal here.
State outlines and towns are Natural Earth; the bloom is each station's reading spread over the ground, not a measurement of anything between stations.
Readings collected from the DOE APIMS public endpoint, roughly every three hours. Not an official source; for advisories, see the department directly.