National Ambient Air Quality Standards

*Annual Arithmetic mean of minimum 104 measurements in a year taken twice a week 24 hourly at uniform interval

**24 boudy/8 hourly or 01 hourly monitored values, as applicable, shall be complied with 98% of the time in a year. 2% of the time, they may exceed the limits but not on two consecutive days of monitoring.

NOTE: 

Whenever and wherever two consecutive values exceeds the limit specified above for the respective category, it shall be considered adequate reason to institute regular or continuous monitoring and further investigations.