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Criteria Pollutants <br />All the criteria pollutants shown in Table 3 above can be directly emitted by the various source <br />types, with the exception of ozone and secondary PM2.5 (also known as condensable particulate <br />matter). <br />Ozone is chemically formed in the atmosphere via complex reactions of oxides of nitrogen <br />(NOx) and volatile organic compounds (VOCs) in the presence of sunlight and under certain <br />meteorological conditions (NOx and VOCs are Ozone precursors). In general, ozone <br />concentrations in the lower atmosphere are highest during warmer months, when the incidence <br />angle of the sun relative to the surface is optimal to support the reactions. In some parts of the <br />western U.S., high winter -time ozone concentrations have been monitored, and these events have <br />generally been linked to areas with high snow cover. It is hypothesized that adequate snow cover <br />(depth) effectively reflects UV radiation striking the ground, essentially `doubling' the potential <br />of the reaction rates relative to the available surface UV. Ozone formation and prediction is <br />complex, non - linear, and generally results from a combination of significant quantities of VOCs <br />and NOx emissions from various sources within a region. Ozone formation may not occur within <br />the resource area, and once formed it has the potential to be transported across long ranges. <br />Therefore, it is typically not appropriate to assess the potential ozone impacts that a single <br />project, where increases in precursor emissions will occur, can have on regional ozone formation <br />and transport. However, the State assesses potential ozone impacts from its authorizing activities <br />on a regional basis when an adequate amount of data is available and where such analysis has <br />been deemed appropriate. For this reason (inappropriate scale of analysis), ozone will not be <br />further addressed in this document beyond the related precursor discussions, and an appropriate <br />qualitative analysis. <br />According to the EPA fine particulate matter (PM2.5) is chiefly comprised of five mass <br />components: organic carbon, elemental carbon (also known as soot or black carbon), ammonium <br />sulfates, ammonium nitrates, and crustal materials (i.e., soil). Primary fine particulate emissions <br />result from combustion processes (including fossil fuel combustion and biomass combustion that <br />occurs in wild fires) and include organic and black carbon. A minority component of primary <br />PM2_5 is made up of crustal elements (i.e. fugitive dust, generally 5 -15 percent). Condensable <br />particulate matter, or secondary PM2.5 particles, are primarily ammonium sulfate and ammonium <br />nitrate formed in the atmosphere from gaseous emissions of sulfur dioxide (S02) and oxides of <br />nitrogen (NOx), reacting with ammonia (NHA The largest constituents of fine particulate are <br />usually organic mass, ammonium nitrates, and ammonium sulfates. Secondary particulates do <br />not result from emissions of fugitive dust (which is the largest emissions category from the <br />Deserado Mine), and thus will not be discussed further in this document. <br />Hazardous Air Pollutants <br />Toxic air pollutants, also known as HAPs, are those pollutants that are known or suspected to <br />cause cancer or other serious health effects, such as reproductive effects or birth defects, or <br />adverse environmental effects. The majority of HAPs originate from stationary sources <br />(factories, refineries, power plants) and mobile sources (e.g., cars, trucks, buses), as well as <br />indoor sources (building materials and cleaning solvents). No ambient air quality standards exist <br />for HAPs, instead emissions of these pollutants are regulated by a variety of laws that target the <br />specific source category and industrial sectors for stationary, mobile, and product <br />DOI- BLM -CO- 110 - 2012 - 0023 -EA 17 <br />