Category: Air Quality

  • Air Pollutants

    The Clean Air Act identifies six common air pollutants that are found all over the United States and can injure health, harm the environment or cause property damage. These pollutants include: The United States Environmental Protection Agency (EPA) has established National Ambient Air Quality Standards (NAAQS) for each of these pollutants. If the air quality…

  • Particulate Matter Overview

    Particulate matter (PM), also known as particle pollution, is a complex mixture of small solid particles and liquid droplets in the air. Some particulate matter, like soot, smoke, dust, or dirt, is large enough to see. Fine particulate matter is so small that it can only be seen through an electron microscope. Particle pollution is…

  • Inversions

    Under normal atmospheric conditions, air is warmer near the ground and colder at higher altitudes. In a temperature inversion, the situation “inverts,” and cold air at the surface gets trapped under a layer of warmer air. During the winter, snow-covered valley floors reflect rather absorb heat, preventing the normal vertical mixing of warm and cold…

  • Particulate Matter 2.5 (PM2.5) Overview

    PM2.5 particulates are fine, inhalable particles or droplets with a diameter of 2.5 microns or smaller. These fine particulates, which are about 30 times smaller than the width of a human hair, can travel deeply into the lungs and cause both short-term and long-term health effects. While larger PM10 particulates can compromise respiratory and cardiac…

  • PM2.5 Moderate Area State Implementation Plans (SIPs) (2009-2014)

    In 2006, the Environmental Protection Agency (EPA) tightened the 24-hour PM2.5 standard from 65µg/m3 (microgram per cubic meter) to 35µg/m3. While the state was in attainment under the previous 24-hour standard, all or parts of seven Utah counties did not meet the new 24-hour PM2.5 standard. Utah continues to attain the 2006 annual PM2.5 standard…

  • Area Designations:
    PM2.5 State Implementation Plan Development

    Nonattainment designation is determined by the EPA when an area or areas within a state persistently exceed the National Ambient Air Quality Standards. The EPA has designated “nonattainment areas” for Particulate Matter having an aerodynamic diameter of 2.5 microns (μm) or less (PM2.5). The two EPA designated areas include: Utah Nonattainment Map Including nonattainment area…

  • Public Comment:
    PM2.5 State Implementation Plan Development

    Public comments are a critical part of the decision making process. The Department of Environmental Quality and its divisions and boards are committed to using the public notice and comment process to improve the decisions they make. The most effective comments: Request actions the agency has legal authority to make. Provide new information the agency…

  • Area Source Rules:
    PM2.5Moderate SIP

    The following rules were adopted as part of the overall emissions control strategy for the PM2.5 SIPs. The rules themselves can be accessed online.

  • PM2.5 Air Trend Plots

    PM2.5 data has been collected at most monitoring stations since 2000. Like PM10, maximum values also tend to occur during wintertime inversions. Also like PM10, trends are somewhat difficult to evaluate because weather plays such a large role in the data collected from year-to-year. This is why the standard is evaluated over a three year…

  • Serious Area PM2.5 State Implementation Plan (SIP) Development (2017-2019)

    The Serious PM2.5 SIP Development is very much an iterative process. The technical foundation of any SIP involves numerous emissions inventories, air quality modeling assumptions, potential emission controls, and ever-fluctuating design values recorded throughout the air monitoring network. The PM2.5 Implementation Rule is very prescriptive about how these numbers must fit together to comprise an…

  • Control Strategies:
    Serious Area PM2.5 SIP

    Disclaimer The Serious PM2.5 SIP Development is very much an iterative process. The technical foundation of any SIP involves numerous emissions inventories, air quality modeling assumptions, potential emission controls, and ever-fluctuating design values recorded throughout the air monitoring network. The PM2.5 Implementation Rule is very prescriptive about how these numbers must fit together to comprise…

  • Public Participation:
    Serious Area PM2.5 SIP

    EPA reclassified two of Utah’s three PM2.5 Nonattainment areas from Moderate to Serious. The State must comply with additional requirements for its PM2.5 State Implementation Plan (SIPs) as a result of this reclassification. Under these new requirements, the State has reviewed its air-quality rules for area, point, and mobile sources and implemented Best Available Control…

  • Technical Analysis:
    Serious Area PM2.5 SIP

    Jump to: Background Emissions Inventories Posted Inventories Modeling Disclaimer The Serious PM2.5 SIP Development is very much an iterative process. The technical foundation of any SIP involves numerous emissions inventories, air quality modeling assumptions, potential emission controls, and ever-fluctuating design values recorded throughout the air monitoring network. The PM2.5 Implementation Rule is very prescriptive about…

  • Particulate Matter 10 (PM10) Overview

    Particulate matter (PM) is a complex mixture of small, solid particles and liquid droplets in the air. PM10 is particulate matter that is 10 microns (μm) or less in diameter. It is a mixture of materials that can include soot, metals, salt, and dust. Major sources include: Air Quality Standards The health-based, National Ambient Air…

  • PM10 State Implementation Plans and Maintenance Plans

    Nonattainment Areas In 1987, the EPA set new air-quality standards for PM10 of 150µg/m3 over a 24-hour period and an average of 50 µg/m3 annually. Utah was initially unable to meet the 24-hour standard and was required to prepare State Implementation Plans for Salt Lake and Utah County. Ogden City was designated nonattainment on September…

  • What is Ozone?

    Ozone is an odorless, colorless gas made up of three oxygen molecules (O3) and is a natural part of the environment. It occurs both in the Earth’s upper atmosphere, or stratosphere, and at ground level in the lower atmosphere, or troposphere. Approximately 90 percent of atmospheric ozone is located in the stratosphere, which begins about…

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