Chronic Disease and the Environment
Frequently Asked Questions (FAQs)
What is a metropolitan area?
How were the metropolitan areas selected?
Why shouldn’t I compare 2001–2006 metropolitan area data to
SMART BRFSS metropolitan/micropolitan data?
Why were 2001–2006 metropolitan area data released if not to
compare to other local area data?
Where can I obtain the BRFSS questionnaires for the data
years in this project?
What is the Air Quality System (AQS) database?
What is the Air Quality Index (AQI)?
What is a metropolitan area?
The term metropolitan area refers collectively to metropolitan statistical
area (MSA), primary metropolitan statistical area (PMSA), or New England
county metropolitan area (NECMA). These geographic subdivisions were defined
by the U. S. Office of Management and Budget (OMB) and used by the U.S. Census
Bureau and the Environmental Protection Agency in 2001.
- Metropolitan statistical area (MSA) — County or group of
counties with the presence of a city with 50,000 or more inhabitants, or the
presence of an urbanized area and a total population of at least 100,000.
- Primary metropolitan statistical area (PMSA) — County or group
of counties that qualify as an MSA and have a total population of 1
million or more.
- New England county metropolitan area (NECMA) — County or group
of counties with a presence of an urbanized area and a total population of
at least 75,000.
Note: NECMAs were defined by OMB to provide an alternative to the
city- and town-based metropolitan statistical areas and consolidated
metropolitan statistical areas typically used in New England.
How were the metropolitan areas selected?
All metropolitan areas with at least 500 completed interviews in the
2001–2006 BRFSS data were selected for inclusion in this project. A total of
69 metropolitan areas met these criteria in 2001, 80 in 2002, 85 in 2003,
87 in 2004, 86 in 2005, and 110 in 2006.
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Why shouldn’t I compare 2001–2006 metropolitan area data to SMART BRFSS metropolitan/micropolitan data?
The definitions of these statistical
areas have significantly changed over time. Changes have consisted chiefly of the recognition of new
areas as they reached the minimum required city or urbanized area population
and the addition of counties to existing areas as new decennial census data
showed them to qualify. In some instances, formerly separate areas have been
merged, components of an area have been transferred from one area to
another, or components of an area have been dropped. The most recent changes
occurred in 2003; therefore, the definitions used for SMART BRFSS are
different than those used in this project.
Because of these historical changes in geographic definitions, users must
be cautious in comparing data for these statistical areas from different
dates. Historical metropolitan area definitions are available for 1999,
1993, 1990, 1983, 1981, 1973, 1970, 1963, 1960, and 1950 at
http://www.census.gov/population/www/estimates/pastmetro.html.
Source: U.S. Census Bureau, Population Division, Population
Distribution Branch
Why were 2001–2006 metropolitan area data released if not to compare to
other local area data?
The 2001–2006 metropolitan area data were released specifically for use with the
2001–2006 Air Quality System (AQS) database to compare measures of air
pollutants in the environment and chronic diseases for that specified time
period.
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Where can I obtain the BRFSS questionnaires for the
data years in this project?
The questionnaires are available in portable document format (PDF) on the BRFSS
Web site under Questionnaires. You will need Acrobat Reader to view and
print these documents.
What is the Air Quality System (AQS) database?
The AQS database, maintained by the U. S. Environmental Protection Agency,
contains measurements of criteria pollutants such as ozone (O3), sulfur
dioxide (SO2), carbon monoxide (CO), and particulate matter (PM2.5, PM10)
concentrations at sites in the 50 United States, plus the District of
Columbia, Puerto Rico, and the Virgin Islands. Ambient measurements are
collected from a network of national, state, and local air monitoring
stations and are used to create the Air Quality Index (AQI). Additional
information on the AQS is available at
http://www.epa.gov/air/data/aqsdb.html.
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What is the Air Quality Index (AQI)?
The AQI is an index for reporting daily air quality based on levels of the
criteria pollutants. The AQI scale runs from 0 to 500 and is categorized
into the following six groups: 0-50 = Good; 51-100 = Moderate; 101-150 =
Unhealthy for Sensitive Groups; 151-200 = Unhealthy; 201-300 = Very
Unhealthy; 301-500 = Hazardous. Additional information on the AQI is
available at http://airnow.gov/.
For more information on the BRFSS in general, see the
BRFSS FAQs.
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