Introduction

How to Use this Report

Use the visualizations of our emissions inventory below to explore the sources of ozone precursor emissions in the summertime within the Northern Wasatch Front Nonattainment Area (NWF NAA). Data presented in this interactive tool represent the summertime Northern Wasatch Front emissions inventory at the time of export. Inventories displayed here are for public consumption and may not necessarily reflect inventories submitted in the final SIP or used in the photochemical model.

  1. Use your mouse to hover over data points to learn more about the Source Classification Code (SCC) and the amount of pollutant coming from that emissions source in tons per day (TPD).
  2. To zoom in, click and drag over the area of the plot you’re interested in.
  3. Use the controls in the upper right corner of each plot to show the plot in full screen mode.
  4. Click on the blue buttons to navigate between sectors and charts.
  5. Double click on a sector in the legend to show data from only that sector. Double click again to show all data.
  6. Read “How to Read a Cumulative Distribution” tab above!

Background Information

This report summarizes emissions from the Northern Wasatch Front (NWF) Ozone Nonattainment Area (NAA), which includes Salt Lake, Davis, and parts of Weber and Tooele counties. This summertime emissions inventory will be used in several applications as part of the Utah Division of Air Quality’s ozone State Implementation Plan (SIP) for the Northern Wasatch Front. The important precursor pollutants that allow ozone to form in the atmosphere are the oxides of nitrogen (NOx) and volatile organic compounds (VOC). Both NOx and VOC are emitted from anthropogenic sources along the Wasatch Front, such as vehicles, paint, or lawnmowers. This report will help you explore the sources of NOx and VOC from many different emission source types.

Emissions inventories are collected and processed through the Sparse Matrix Operating Kernel Emissions Model (SMOKE). SMOKE modeling spatially allocates, temporalizes, and chemically speciates annual emissions estimations from the emissions inventories. Emissions inventories contain annual estimations of the amount of pollutant emitted from a given emission source, typically represented in tons of that pollutant per year. SMOKE takes that annual emission rate and some other inputs to determine 1) where the emissions are coming from geographically, 2) when those emissions are emitted throughout the year, month, and week, and 3) what chemical species are included in the emission of pollutant. From SMOKE, air quality scientists get emissions data in tons of pollutant per day for a given emissions source.

Emissions sources are identified by a Source Classification Code (SCC). Each SCC represents a unique source category-specific process or function that emits air pollutants.

SCC’s and their emissions are classified into broader source sectors. Sectors relevant to the Northern Wasatch Front Ozone State Implementation Plan include: nonpoint, point, electric generating units (EGU’s), onroad mobile, nonroad mobile, airports, rail, solvents, and livestock.

  • EGU’s: Electric generating units, or EGU’s, include emissions from our power plants. These point sources are located at a fixed, stationary location.
  • Airports: Emissions from all aircraft and ground support equipment. These are treated as point sources located at a fixed, stationary location.
  • Point: Any non-EGU or airport point sources, including large industrial facilities. For the NWF NAA, point sources only include sources with annual emission greater than 100 tons per year of NOx or VOC.
  • Nonpoint: Nonpoint sources include emissions that individually are too small in magnitude to report as point sources. Examples include residential heating, residential charcoal grilling. For the NWF NAA, nonpoint sources also include any point sources with annual emission less than 100 tons per year of NOx or VOC.
  • Rail: Emissions from railroads. Examples include emissions from FrontRunner trains and some rail yard emissions.
  • Solvents: This sector includes emissions from asphalt paving, and commercial and consumer solvent use (e.g. hairspray, household cleaning products).
  • Livestock: Emissions from the agricultural production of livestock, including emissions from manure.
  • Onroad: Includes emissions from onroad vehicles that use gasoline, diesel, and other fuels. Onroad vehicles include light-duty and heavy-duty vehicles operating on roads, highway ramps, and during idling.
  • Nonroad: Includes emissions from off-road mobile sources that use gasoline, diesel, and other fuels. These source types include construction equipment, and lawn and garden equipment.

How to Read a Cumulative Distribution

A cumulative distribution helps us easily understand emissions sources that contribute most significantly to the total pollution. All source classification codes (SCC’s) are sorted from the greatest pollutant emission rate (tons per day) to the least emission rate. The SCC with the largest pollution rate is assigned rank 1. The SCC with the smallest pollution rate is given the highest rank. On the cumulative distribution plot, this rank is the “cumulative rank” and is displayed on the x-axis.

The largest pollutant emissions rate (cumulative rank #1) is added the next largest pollutant emissions rate (cumulative rank #2), and so on. This is called the cumulative sum. The very last SCC in the distribution (largest cumulative rank) will have a cumulative sum equal to the total of all pollutant emissions rates in the data set. For every SCC, we divide the cumulative sum of emissions rates by the total sum of emissions rates - this is the cumulative percentage, shown on the y-axis of the plot.

SCC’s that contribute significant to the total percentage of pollutant emissions appear on the left-most side of the distribution with small cumulative rankings. Each SCC causes the cumulative percentage to increase rapidly. SCC’s with smaller emissions rates do not contribute very much to the entire pollutant picture, so they appear near the top of the graph. These SCC’s cause the distribution to gradually approach 100%.

DAQ environmental scientists use a cumulative distribution plot to quickly determine which SCC’s are responsible for the most emissions in a given inventory. Any SCC with a cumulative percentage less than 80% is interesting as a potential emissions source to control.

Northern Wasatch Front VOC and NOx Inventories

Use the blue buttons here to toggle between VOC and NOx inventories.

Summertime VOC Inventory

(Above) Bar chart showing the VOC emissions from each category in the inventory broken out by source classification code (SCC). These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all sources and SCC’s in the Nonattainment Area. These plots show the ranking of SCC’s by the percent they contribute to emissions. The lowest point on the plot accounts for the largest amount of emissions, with each point going up accounting for the next largest source category. In this plot, the largest source contributing to VOC emissions is Personal Hair Care Products (SCC 2460110000) accounting for ~15% of emissions, followed by household products (~10%). The red horizontal line indicates the 80% threshold, so all SCC’s below this line account for 80% of the emissions in the inventory and any SCC above this line likely accounts for a proportionally smaller amount. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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Summertime NOx Inventory

(Above) Bar chart showing the NOx emissions from each category in the inventory broken out by source classification code (SCC). These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all sources and SCC’s in the Nonattainment Area. These plots show the ranking of SCC’s by the percent they contribute to emissions. The lowest point on the plot accounts for the largest amount of emissions, with each point going up accounting for the next largest source category. In this plot, the largest source contributing to VOC emissions is Diesel Trucks used for Construction and Mining (SCC 2270002051) accounting for ~15% of emissions, followed by Highway Diesel Trucks (~10%). The red horizontal line indicates the 80% threshold, so all SCC’s below this line account for 80% of the emissions in the inventory and any SCC above this line likely accounts for a proportionally smaller amount. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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Summertime Northern Wasatch Front VOC Inventory by Sector

Use the blue buttons here to toggle between emissions inventory sectors.

SOLVENTS

(Above) Bar chart showing the VOC emissions from the solvent sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all solvent sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the solvent sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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ONROAD

(Above) Bar chart showing the VOC emissions from the onroad mobile sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all onroad mobile sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the onroad mobile sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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NONROAD

(Above) Bar chart showing the VOC emissions from the nonroad mobile sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all nonroad mobile sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the nonroad mobile sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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NONPOINT

(Above) Bar chart showing the VOC emissions from the nonpoint sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all nonpoint sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the nonpoint sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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POINT

(Above) Bar chart showing the VOC emissions from the point sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all point sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the point sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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AIRPORTS

(Above) Bar chart showing the VOC emissions from the airports sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all airport sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the airports sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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RAIL

(Above) Bar chart showing the VOC emissions from the rail sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all rail sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the rail sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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LIVESTOCK

(Above) Bar chart showing the VOC emissions from the livestock sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all livestock sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the livestock sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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EGUs

(Above) Bar chart showing the VOC emissions from the EGU sector broken out by source classification code (SCC), with the total VOC tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all electric generating unit (EGU) sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total VOC from the EGU sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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Summertime Northern Wasatch Front NOx Inventory by Sector

Note that the Livestock sector is absent; all NOx emissions associated with livestock production are included in the Nonroad sector. Use the blue buttons here to toggle between emissions inventory sectors.

ONROAD

(Above) Bar chart showing the NOx emissions from the onroad mobile sector broken out by source classification code (SCC), with the total NOx tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all onroad mobile sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total NOx from the onroad mobile sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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NONROAD

(Above) Bar chart showing the NOx emissions from the nonroad mobile sector broken out by source classification code (SCC), with the total NOx tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all nonroad mobile sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total NOx from the nonroad mobile sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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NONPOINT

(Above) Bar chart showing the NOx emissions from the nonpoint sector broken out by source classification code (SCC), with the total NOx tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all nonpoint sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total NOx from the nonpoint sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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POINT

(Above) Bar chart showing the NOx emissions from the point sector broken out by source classification code (SCC), with the total NOx tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all point sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total NOx from the point sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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AIRPORTS

(Above) Bar chart showing the NOx emissions from the airport sector broken out by source classification code (SCC), with the total NOx tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all airport sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total NOx from the airport sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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RAIL

(Above) Bar chart showing the NOx emissions from the rail sector broken out by source classification code (SCC), with the total NOx tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all rail sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total NOx from the rail sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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EGUs

(Above) Bar chart showing the NOx emissions from the EGU sector broken out by source classification code (SCC), with the total NOx tons per day displayed at the top of each bar. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and how much is emitted in the Nonattainment Area.

(Above) A cumulative distribution plot for all electric generating unit (EGU) sources and SCC’s in the Nonattainment Area. SCC’s along the distribution below the red horizontal line are the most significant contributors to the total NOx from the EGU sector in the NWF NAA. These plots are interactive, use your mouse to hover over different SCC’s to learn more about the SCC and where it ranks in the inventory. Read the “How to Read A Cumulative Distribution Plot” tab at the top of this page for more information.

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