Table 3.

Air quality standard guideline and interim targets for particulate matter (PM_2.5): 24-hour mean.³⁶

S.No	24-hour mean level	PM10 (µg/m3)	PM2.5 (µg/m3)	Basis for the selected level based
1	WHO interim target 1 (IT-1)	150	75	Based on published risk coefficients from multicenter studies and meta-analyses (about 5% increase in short-term mortality over AQG)
2	WHO interim target 2 (IT-2)	100	50	Based on published risk coefficients from multicenter studies and meta-analyses (about 2.5% increase in short-term mortality over AQG)
3	WHO interim target 3 (IT-3)	75	37.5	About 1.2% increase in short-term mortality over AQG
4	WHO air quality guidelines (AQG)	50	25	Based on relation between 24-hour and annual PM levels