| Statewide
Mobile Source Emissions by County
State Implementation Plan (SIP) InventoriesSince 1970, the
federal Clean Air Act has required states to develop comprehensive
emissions inventories for the five primary criteria pollutants
(CO, NOx, SO2, VOC, and PM) on a periodic basis. Early inventories
were not so comprehensive nor as accurate as more recent ones,
so it is not easy to compare inventories for time periods which
are separated by many years. The requirement for comprehensive
state-wide inventories stems from needs for control strategy
modeling contained in State Implementation Plans (SIPs) and
for tracking progress in reducing emissions of pollutants which
contribute to violations or exceedances of ambient air quality
standards. In Vermont's case, only the mobile source emissions
(CO, VOC, & NOx) are important for strategies addressing regional
ozone violations.
Vermont has submitted four "SIP" inventories containing estimates
of these three mobile-source air pollutants since 1970. These
were done for the years 1975, 1990, 1997 and most recently 1999.
The 1975 inventory did not incorporate many of the more sophisticated
methods for estimation of emissions that the latest two have
used, so at this point, we do not rely on the accuracy of the
1975 inventory for planning purposes.
Click here for additional
maps & tables of mobile-source related emissions by Vermont
County for the years 1990, 1997 and 2007.
Last Updated:1/22/03
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Air Pollution Control Division 
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