Ambient Air quality Monitoring Guidlines. - Maharashtra Pollution ...

the pollutant and accordingly select the sampling period and rate of sampling
(Lit/min.). After completion of the sampling, remove the impingers, measure the
sample volume. Either make up the sample volume or note the final volume of
the absorbing solution. Preserve the samples as mentioned (7.0).
11.0 CALCULATIONS
The following equation is used for the calculation of gaseous pollutants in the
ambient air.
(A-B) x G.F x Tv x 1000
Concentration (µg/m 3 ) = ---------------------------------
T x Fr x Va
A = Absorbance of exposed sample at a particular wavelength.
B = Absorbance of reagent blank solution.
G.F = Graph factor of the concerned pollutant. (µg/abs.)
(Graph factor is the inverse of the slope)
Tv = Total volume of the exposed sample (ml)
1000 = Conversion factor from litres to m 3
T = Total sampling time (min.)
Fr = Sampling flow rate (Litre/min.)
Va = volume taken for analysis (ml).
Note: T x Fr is equal to total volume of air in litres. The concentration of the
gaseous pollutants can also be expressed in µg/Nm 3 after correcting the total
volume of air at 25 o C temperature and 760 mm Hg pressure.
11.0 REFERENCES
1. Indian standard IS: 5182 (Part v) - 1975.
2. ASTM standard D1605 -60/90.
3. Methods of air sampling and analysis, Published by ISC, 37-42.
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