Environmental Engineering Reference
In-Depth Information
and not on any relationship to ambient air quality on assimilative capacity
of the atmosphere. In the absence of recording instruments for emission
monitoring, limits specifying pollutant loads per unit of production have
little meaning. Concentration monitoring is on grab samples and is rather
infrequent, and hence, enforcement is rather lax.
Assimilative capacity of atmosphere:
Prediction of expected increments in
pollutant concentrations due to proposed major industries, using modeling
dispersions of the likely emissions, has become an integrated part of EIAs
and environmental clearances for the last 15 years. However, this does not
appear to have contributed very much to air quality management due to
doubtful meteorological data and models that have never been validated
for local conditions. Modeling is done on a case-by-case basis, and in
the absence of firm meteorological or background air quality data; there
is unlimited scope to manipulate to get projects cleared. A few regional
EIA studies (or what are called “carrying capacity” studies) have been car-
ried out (e.g., for Doon Valley, National Capital Region at Delhi, and the
Jamshedpur Region), but so far, these have not been used for planning or
granting clearance for industrial units. Thus, assimilative capacity of the
atmosphere is a new concept and the greatest difficulty in its use is the lack
of appropriate meteorological data. The first competent effort in this field
appears to be that underway at Patna in Bihar State since August 1999 by
Envirotech Instruments Pvt. Ltd. of New Delhi, which is collecting primary
meteorological data at the site (including wind and temperature profiles and
mixing heights).
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Pollution load trading:
This concept has so far not arrived in India, and
each project is treated as an individual case. In the highly dusty and politi-
cized Indian scenario, pollutant load trading may not be easy, even in years
to come.
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Evaluation of Performance
It is wrong to say that there have been no
significant improvements in the air quality scenario in India during the previ-
ous 10 years. The most noticeable improvements have been in the levels of
SO
2
in urban areas, primarily due to a switch from using sulphur-free liquid
petroleum gas instead of other locally available fossil fuels. A recent reduc-
tion in sulphur content of diesel (from around 1 percent to below 0.1 percent)
is bound to further improve the situation. The introduction of lead-free gaso-
line and of catalytic converters on all new cars has drastically brought down
concentrations of lead in ambient air of the metro cities. However, the lev-
els of particulates have not abated, and concentrations of nitrogen oxides are
rising. All these changes have essentially resulted from reductions in vehicu-
lar and other nonindustrial emissions under court directions. Although a lot of
emission control systems have been installed and commissioned in industries,
and industrial units and regulatory agencies claim large improvements in com-
pliance of emission standards, it would be a rare case that reports even the
slightest improvement in the ambient air quality due to the better management
