CHAPIS Emissions Maps

Welcome to CHAPIS!
Find your neighborhood on the air pollution map.

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What is CHAPIS?

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The California Air Resources Board has developed an internet-based mapping tool that allows you to look at a map to view sources of air pollution. We call this system CHAPIS (the Community Health Air Pollution Information System). CHAPIS is about making information regarding air pollution emissions available to you in ways that are more understandable and more visual. The air pollutant emission information contained in CHAPIS is provided for general informational purposes. Please consult your local air district for the most recent data available for specific facilities. The ARB should be contacted regarding mobile source emissions.

The development of the information used in CHAPIS was a joint effort between the ARB and the State's 35 local air pollution control or air quality management districts. Districts provide the data for facilities in their jurisdiction. Everyone contributing to the CHAPIS system has made a major effort to make information in CHAPIS as accurate as possible. However, as with any system that is using millions of pieces of information coming from multiple sources, we anticipate that users may find some information that is not up-to-date or is not accurate. In addition, please keep in mind that due to the way emission information is reported, collected, and managed, there can be a substantial lag time between when the emissions occurred and the reporting of the information to the local air districts' and ARB's emission inventory databases.

Currently, most of the data are from 2001, although some of the data about toxic emissions can be from various years from 1990 to 2001 (see more discussion of the Air Toxics "Hot Spots" program below). ARB will be making regular updates to CHAPIS to correct data problems as they are brought to our attention. We encourage everyone to make use of our "Email Comments" link at the bottom of the maps to bring any data problems to our attention.



What can CHAPIS do?

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You can use these maps to answer questions like: What are the major sources of air pollution within several miles of my home? What are the relative contributions of mobile sources and stationary sources? What sources are near my son or daughter's school? Which chemicals are emitted by a particular facility or mobile sources in this area? To answer these questions you must provide CHAPIS with a location of interest (e.g., county or zip code) and choose which types and sources of pollution you would like to explore.

From the CHAPIS map there are also links to other data sources, such as tools to query the statewide emission inventory database and the network of air monitoring stations.

The air pollutant emission information contained in CHAPIS is provided for general informational purposes only. Please consult your local air district for the most recent data available for specific facilities. In addition, please see the discussion of data limitations in the "What are the limitations?" section below.


What are the limitations?

Please keep in mind that there are limitations to CHAPIS, and ways to use it most effectively. We have tried to provide helpful background information in the CHAPIS Help links, the on-line Tutorial, the FAQ link, as well as on the next pages. Some of the key things to note include the following.

(1) Emissions Are Not the Same as Exposure: Please keep in mind that the emissions alone do not fully represent where and what extent of exposures to air pollution or possible health risks may occur. Weather and wind can result in exposures that occur in different locations from where the emissions actually occurred, and can create new pollutants due to chemical reactions in the atmosphere. Also, a larger number for emissions of a particular chemical may not be as important as smaller amounts of more potent chemicals. While air pollutant emissions information can serve as an indicator of local air pollution, it is the exposure to emissions that influences health effects. Exposure is the amount of pollution that someone actually breathes or otherwise ingests at different locations. Exposure varies with how far away the source is, how the emissions are released into the air and dispersed by the wind, and in what locations a person spends their time doing various activities. Exposure to air pollutants can also occur from indoor sources such as cooking, cleaning, and smoking; however, CHAPIS does not address the contribution of indoor sources. The importance of the exposure to health risk also depends on the combination of multiple air pollutants, the relative toxicity of the pollutants, and many other factors. The CHAPIS web tool does not map the exposure levels or the health risks associated with the pollutants and sources it tracks. (See more discussion of exposure on the next page.)

(2) CHAPIS Does Not Contain All Air Pollution Sources Or All Air Pollutants: It is important to keep in mind that CHAPIS does not contain information on every source of air pollution and does not show every chemical emitted. CHAPIS is being developed in stages to assure data quality. For example, cars and trucks are covered in the gridded mobile emissions for many criteria and toxic pollutants, but they can emit additional pollutants (e.g., PAHs) that are not covered at this time due to lack of data. Large industries and small businesses are being phased in by categories of facilities to ensure quality. The initial release of CHAPIS includes about 2,000 large industrial and small commercial facilities. The initial release covers facilities emitting the bulk of the criteria pollutant (smog-forming) emissions and many of the larger or important sources of toxic air pollutants. However, overall at this time, there is a much lower number of facilities with toxic air pollutant information in CHAPIS than for criteria pollutants. It is a major objective of CHAPIS to include all of the largest air pollution sources and those with the highest documented air pollution risk. CHAPIS will be updated on a periodic basis and additional facilities will be added to CHAPIS as more data become available.

(3) Emission Estimates Are Based on Average Conditions: CHAPIS is intended to provide a visual, map-based window into the ARB's emission inventory database. The emission inventory covers routine, annual air pollution emissions. Process upsets and accidental releases are not included.

(4) Emission Estimates Are Based on a Variety of Factors and Assumptions, and Are Not Exact Measurements of Emissions: Emission inventories provide estimates of the air pollution released from sources but are not an exact accounting of actual amounts. Emission estimates are based on overall average conditions (not any specific day), and are generally based on a limited number of source tests, available emission factors, or material balance calculations for similar types of sources. The exact locations of the releases may not be reflected in detail, nor the types of stacks or other release characteristics that influence how the emissions may affect downwind areas.

(5) Industrial and Commercial Facilities Are Not the Only Sources of Air Pollution: While the locations of industrial and commercial facilities appear on the CHAPIS maps, they are not the only sources of air pollution. Cars and trucks are responsible for most of the air pollution in the State, and generally pose the most prevalent health risks. CHAPIS has tools to show the combined contributions of cars and trucks, together with other sources like industrial sites, using what we call the gridded emissions. The Gridded Emissions options provide a way to see the combined effects of all types of sources reported for a given air pollutant within a series of square grid cells covering an area. (Depending on how much the user zooms in, the size of the grid cells will be either 4 km x 4 km cells, or 1 km x 1 km cells.) The "Calculate Combined Stat(istic)s" feature further provides a summary list and bar chart for all the grid cells in the entire map viewing region.

(6) Choosing a Pollutant: The CHAPIS maps can only symbolize the emissions of one air pollutant choice at a time. However, users can then use the "Identify" or "Calculate Stats" tools to hyperlink to the ARB's underlying emission inventory database for more information about each facility. In addition, there are several pick-list choices under "Select pollutant" that provide combined values (e.g., All Toxic Compounds, Other, and Potency-Weighted Lbs).

(7) Informational Purposes: The air pollutant emission information contained in CHAPIS is provided for general informational purposes only. Please consult your local air district for the most recent data available for specific facilities.

Browser Tips
CHAPIS is best viewed using Internet Explorer (version 5 or higher). Netscape Navigator (version 4.6 or higher) is also generally satisfactory. CHAPIS uses pop-up windows to display some results, so pop-up blockers should be disabled. For best results, use a screen setting of 1024 x 768 pixels, and use a "Text Size" setting of Medium (or Small), to ensure that all buttons will be visible without excessive scrolling or re-sizing of windows. The next pages provide tips for new users, as well as links to learn what actions are underway to reduce air pollution and toxic risks. Click on CONTINUE to learn more about what you can do in CHAPIS.



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What information does CHAPIS have now?

We have already included a large amount of information in this first release of the CHAPIS tool for you to view, and there will be more over time. CHAPIS includes all the available data for mobile sources (cars and trucks, and off-road equipment) and area-wide sources, as well as about 2,000 large industries and small businesses (stationary source facilities). The initial release includes facilities emitting the bulk of the criteria pollutant (smog-forming) emissions and many of the larger or important sources of toxic air pollutants. However, overall at this time, there is a much lower number of facilities with toxic air pollutant information in CHAPIS than for criteria pollutants. We are phasing-in the industries and businesses by categories of facilities to help ensure that the information we provide is as accurate as possible. We are working closely with the local air districts.

For criteria (smog-forming) pollutants, facilities that emit 10 or more tons per year of nitrogen oxides, sulfur oxides, carbon monoxide, PM10, or reactive organic gases are included. For toxic pollutants, facilities are being phased in by categories in collaboration with the local air districts. Large facilities including petroleum refineries and power plants of 50 megawatts or more are included, as well as facilities that conducted health risk assessments under California's Air Toxics "Hot Spots" program in the categories of chemical manufacturing, metal fabrication, and aerospace/electronics manufacturing. In the future, the remaining "Hot Spots" risk assessment facilities and other industries and smaller businesses, such as gas stations and dry cleaners, will also be added.



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Emission Inventory

This page last reviewed May 22, 2008



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