CPCB’s Guidelines on Sample collection, Transportation and Analysis:

---

• The monitoring of pollutants is carried out for 24 hours (4-hourly sampling for gaseous pollutants and 8-hourly sampling for particulate matter) with a frequency of twice a week, to have one hundred and four (104) observations in a year so that results obtained can be compared with NAAQS.
• The monitoring is being carried out with the help of all the Regional Offices the Board and financial assistance from Central Pollution Control Board for operation and maintenance of the stations.
• Large number of personnel and equipments are involved in the sampling, chemical analyses, data reporting etc. It increases the probability of variation and personnel biases reflecting in the data, hence it is pertinent to mention that these data be treated as indicative rather than absolute.