Taiwan is predominately - “Moderate” - Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
and,
“Unhealthy for Sensitive Groups” - Members of sensitive groups may experience health effects. The general public is not likely to be affected.
I would question the meaning of ‘moderate’ air pollution, ‘moderately bad’ is still bad and South and Central Taiwan are really bad at times!
A handy way to remember is that anything over 35 ug/m3 PM2.5 concentration is considered bad. But even below that there are significant health effects especially on growing children.
This is the calculator you need to make sense of different indexes and numbers.
airnow.gov/index.cfm?action= … _conc_calc