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Estimates of Emissions with Smog-Forming Potential for Selected Industry Sectors

Smog-forming Potential

This document develops estimates of the potential for air emissions from selected industry sectors to impact the formation of smog.  The analysis will focus on those emissions that most directly influence the principal health effects of smog, which are associated with ozone and particulate matter. 

• Ground level ozone is formed primarily through a reaction between certain volatile organic compounds (VOCs) and nitrogen oxides (NOx), in the presence of sunlight.  Ozone is a reactive form of oxygen that damages the tissues of the lung on contact, decreasing lung capacity and aggravating conditions such as asthma.
• Fine particles are typically produced in combustion processes.  Such particles can collect in minute air passages in the lung, where they cannot be easily dislodged, and can cause significant deterioration of lung tissue.  This effect can occur simply because of the particle size, and is not necessarily related to the toxicity of the bulk material.

The National Emission Trends (NET) database, maintained by EPA, provides data on six so-called "criteria air pollutants".  Three of the criteria pollutants, NOx, particulates, and VOCs, are particularly relevant to the deleterious effects of smog, as noted above.  Data from 1999 are available through a search tool located on the EPA AirData website, and can be downloaded in a format particularly convenient for this analysis, sorted into four-digit SIC codes.

Data from individual four-digit SIC codes have been grouped into clusters, referred to in this analysis as "sectors of interest".   Tables 1 through 4 present the 1999 NET data in four alternative formats:

• alphabetically
• sorted by VOC
• sorted by NOx
• sorted by PM2.5

Table 1.  Sectors of interest and 1999 air emissions of pollutants with smog-forming potential, in tons per year

Table 2.  Sectors of interest and 1999 air emissions of pollutants with smog-forming potential, in tons per year,

sorted by VOC