The Atmospheric System EMISSIONS

Finally, through legislative and administrative action, health-protective and cost-effective risk-management decisions can be made, and regulatory actions implemented, that directly affect the starting point of our atmospheric system, that is, the primary emissions and their sources. 

To place the remainder of this book on atmospheric chemistry in perspective, the various components of our atmospheric system are treated briefly next. 

Emissions inventories are typically obtained by combining the rate of emissions from various sources (the emission factors ) with the number of each type of source and the time over which the emissions occur. 

Inventories are compiled in various formats. For example, they can be assembled for various individual anthropogenic processes such as refining, or natural processes such as volcanic eruptions, in which emissions of all of the relevant species associated with that event are estimated. Alternatively, and more commonly, emissions inventories are compiled by species, showing the various sources that contribute to the total emissions of each. 

Emission factors for various sources in the United States have been published by the Environmental Protection Agency in the form of the document 

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