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

The monthly average concentration of SPM (1995-2001) and RSPM (1999-2001) measured at
BSZ Marg is shown in Figure 2.2 and 2.3 respectively. The strong and medium winds during
April to June creates turbulent conditions and local disturbances in the environment which cause
frequent dust storm and hazy conditions. These dust storms and hazy conditions build up high
particulate matter levels in the ambient air, mostly constituting soil borne particles.
Concentration (µg/m 3 )
600
500
400
300
200
100
0
January
February
March
April
May
June
M onths
Figure 2.2: Monthly Average Concentrations
(1995-2001) of SPM at BSZ Marg, New Delhi.
During monsoon, mostly winds from east prevail. Most frequent rains washes down the air borne
particulates and other pollutants generated and dispersed from the sources in the environment,
therefore the period from July to September is cleaner period in the year. The winter months of
are relatively much calm than other months. The prevailing calm conditions facilitate more
stability to atmosphere and consequently slow dispersion of pollutants generated and help in
build up of pollutants in vicinity of the pollutant sources. Lower average mixing height in winter
season results in less volume of troposphere available for mixing and hence higher SPM and
RSPM concentrations.
67
July
August
September
October
November
December