Border Air Quality Data - About the HAP Monitor Values Report
What Does the Report Tell Me ?
The border air quality data HAP Monitor Values Report displays measurements of hazardous air pollutant (HAP) concentrations recorded by monitoring sites within approximately 65 miles (100 kilometers) of the U.S.-Mexico border. The report shows a yearly summary of the measurements at individual monitoring sites, and descriptive information about the sites.
Hazardous air pollutants are substances that are known or suspected to cause serious health problems. Section 112(b) of the Clean Air Act currently identifies a list of 188 pollutants as HAPs. Some of those are further subdivided for air monitoring procedures, resulting in about 200 HAPs that may be monitored for their ambient concentrations in air.
Each row of the HAP Monitor Values Report displays air pollution levels measured at a single monitoring site in a single year. The same site may appear in multiple report rows if it has more than one monitor or if you include multiple data years in the report.
Air monitoring data usually are incomplete for the latest year available in this report. Therefore, comparing reported values for the latest year with prior years may not be meaningful.
How Can I Customize the Report ?
You can use the SORT buttons in each report column to change the order of rows in the report. The default sort order is monitoring site ID, which arranges rows in order of state, county, and monitoring site.
The reporting software automatically adds year as a secondary sort key for most report columns. If a report includes data for multiple years, rows having identical values for the primary sort key, which you choose with the SORT buttons, are arranged in ascending order by year.
Detail or Summary
This is always a detail report. Omitting optional report columns does not change the level of summarization. A row of the report always displays data for a single monitoring site for a single year.
This report potentially can include nearly 40 data columns if you select all optional columns. Viewing such a "wide" report in a browser requires horizontal scrolling, and printing the full report width probably is not possible.
- Row #
- Sequence number of report rows (lines). Sequence numbers are not associated
with particular rows; they simply enumerate the rows of a report from first
to last. Thus, choosing an alternate sort order for a report would change the
sequence numbers associated with particular rows.
- Pollutant Values
- # Obs
- Number of days in the year for which values (observations) were reported.
- 1st Max, 2nd Max, 3rd Max, 4th Max
- The four highest values for the year. Each value is a 24-hour average.
- Arithmetic average of all 24-hour values for the year.
If a monitoring site reports a pollutant concentration that is less than the minimum detectable level for the measurement procedure used, a value equal to one-half the minimum detectable level is substituted for the reported concentration in the AQS database. Pollutant values given in this report - maximum and mean values - reflect the half-minimum-detectable substitutions.
- The units of measurement for pollutant concentration:
- ppbC = parts per billion carbon
To convert from ppbC to parts per billion by volume (ppb), divide pollutant concentration by the number of carbon atoms in the pollutant molecule. In other words, ppbC = ppb * (number of carbon atoms).
- µg/m3 = micrograms per cubic meter
- ng/m3 = nanograms per cubic meter
- ppbC = parts per billion carbon
- The name of the hazardous air pollutant for the row of data.
- The calendar year to which data pertain - the year in which pollutant
concentrations were measured. The report includes this column only
when you select multiple years.
- Monitor ID
- The AQS database identification code for a monitor. An AQS monitor ID has
the following parts:
- FIPS state code (2 digits)
- FIPS county code (3 digits)
FIPS is the acronym for Federal Information Processing Standards, which defines codes used in most U.S. government information systems.
- AQS site code (4 digits) - an arbitrary code that identifies a particular monitoring site within a county
- AQS parameter code (5 digits) - identifies the hazardous air pollutant measured
- AQS monitor number (1 or 2 digits) - a sequence number that distinguishes among monitors for the same pollutant at the same site, also known as parameter occurrence code (POC).
- Monitor Type
- The administrative classification of an air monitoring station. This value
indicates what type of agency established the monitor or what monitoring program
it is associated with. A monitor with several roles may have multiple monitor
types. Values are:
- SLAMS (State and Local Air Monitoring Stations)
- NAMS (National Air Monitoring Stations)
- PAMS (Photochemical Assessment Monitoring Stations - detailed study of ozone and its precursors)
- Unofficial PAMS (site certification pending)
- Index Site
- Non-EPA Federal (operated by a Federal agency other than EPA)
- Trends Speciation (Speciation Trends Network for fine particulate matter)
- Measurement Scale
- The geographic extent of air quality measurements made at the site. Measurements
made elsewhere within that geographic scope should be equivalent. Values are:
- Middle Scale
- Regional Scale
- Urban Scale
- Dominant Source Type
- The class of air pollution sources that normally produce most of the air pollution
measured at the site. Values are:
- Area - small stationary sources (homes, offices) and diffuse sources (agriculture, wildfires)
- Mobile - vehicles of all types
- Point - stationary sources (factories, power plants)
- Monitoring Objective
- The primary reason for measuring air pollution levels at the site. When an
objective pertains to a specific city, urbanized area, metropolitan statistical
area (MSA), or consolidated metropolitan statistical area (CMSA), the name of
the area is given in parentheses. Typical monitoring objectives are:
- General/Background concentration
- Population Exposure
- Highest Concentration
- Site Address
- Address where the monitoring site is located.
- Name of the city, town, village or other municipality in which the site is
located. Blank if the site is not located within such a jurisdiction, or if
no value was provided.
- City Code
- The 5-digit FIPS code for the city, town, village or other municipality
(a "named populated place") in which the monitoring
site is located. Blank or zero if the site is not located within
such a jurisdiction, or if no value was provided.
- Name of the county (or equivalent jurisdiction) in which a site is located.
- County Code
- Code for the county (or equivalent jurisdiction) in which a site
is located, consisting of 2-digit FIPS state code and 3-digit FIPS
county code. FIPS is the acronym for
Federal Information Processing Standards, which defines codes used
in most U.S. government information systems.
- Postal abbreviation for the U.S. state in which a site is located. The nation
of Mexico has the "state" abbreviation MX. [ Details ]
- Border Region
- Name of a section of the U.S.-Mexico border area in which the site
is located. A border region is usually encompasses adjacent U.S. and
Mexican urban areas. A border region is the smallest geographic
area that you may select for border air quality reports.
- Land Use
- The prevalent land use within 1/4 mile of the site. Values are:
- Blighted Area
- Military Reservation
- Location Type
- A general characterization of the setting where the site is located. Values
- Urban and Center City
- Coordinates of the site location, in degrees. Negative values of longitude
indicate locations west of the prime meridian. Blank if no value was provided.
- Locational Accuracy
- The estimated accuracy (uncertainty) of the site location, in meters,
as specified by latitude-longitude coordinates. Blank if no value was
- Locational Method
- The method used to determine the site location, as specified by latitude-longitude
coordinates. Blank if no value was provided.
- Distance to City Center
- Distance in miles to the city central business district. Direction
may be given also, as a compass point: N for north, NE
for northeast, etc. Blank if the site is not located in a city, or
if no value is available.
- City Population
- Population (in year 2000) of the city, town, village or other municipality
in which the site is located. Blank if the site is not located within
such a jurisdiction, or if no value is available.
- Urbanized Area
- Name of the urbanized area in which the site is located. Blank if
the site is not located within such a jurisdiction, or if no value
was provided. The U.S. Census Bureau defines an urbanized area as
a place (city) and the adjacent densely-settled surrounding territory
that together have a minimum population of 50,000 people.
- UA Code
- The 4-digit Census Bureau code for the 1990 urbanized area in which
the site is located. Blank or zero if the site is not located within
such an urbanized area, or if no value was provided.
- MSA (Metropolitan Statistical Area)
- Name of the MSA in which the site is located. Blank if the site is not
located within an MSA, or if no value was provided.
A metropolitan statistical area consists of one or more counties having a combined population of at least 100,000 people, containing a city or urbanized area with a population of at least 50,000 people. (In New England states, the population threshold is 75,000 and MSAs comprise cities and towns rather than counties.) An MSA may contain more than one city larger than 50,000 population, and it may include counties in multiple States.
- MSA Code
- The 4-digit FIPS code for the metropolitan statistical area (MSA)
in which the site is located. Blank or zero if the site is not located
within a metropolitan statistical area, or if no value was provided.
- CMSA (Consolidated Metropolitan Statistical Area)
- Name of the CMSA in which the site is located. Blank if the site is not
located within a CMSA, or if no value was provided.
A consolidated metropolitan statistical area consists of one or more MSAs that have a combined population of at least one million people. The constituent MSAs are called primary MSAs (PMSA).
- CMSA Code
- The 4-digit FIPS code for the consolidated metropolitan statistical
area (CMSA) in which the site is located. Blank if the site is not
located within a consolidated metropolitan statistical area, or if
no value was provided.
- AQCR (Air Quality Control Region)
- Name of the AQCR in which the site is located. Blank if no value
An air quality control region is a group of counties within a state (or multiple adjacent states) that share common geographical or pollutant concentration characteristics based on a common pollutant source.
- AQCR Code
- The 3-digit AQS code for the air quality control region (AQCR)
in which the site is located. Blank if no value was provided.
- Site Established
- The date (day, month, year) when the monitoring site began measuring air pollutant
concentrations. This date pertains to the entire site, and not necessarily to
a specific pollutant (monitor).
- Site Terminated
- The date (day, month, year) when the monitoring site stopped operating.
No value is displayed if the site is still operating.
- Site Detail
- You can view a complete listing of all hazardous air pollutants reported by
a monitoring site by clicking on the "See All HAPs" link in each row.
A Site Detail report is displayed in response to your click. It shows annual
summary values of every HAP reported by the site for the year associated with
the row of the main report in which you clicked. The Site Detail column
is included in reports whose rows pertain to distinct monitoring sites. It is
not available if report rows represent larger aggregations, such as a county
or a state.