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)?
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.
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.
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/metro.
Source: U.S. Census Bureau, Population Division, Population Distribution Branch
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.
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.
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/airdata/.
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://www.airnow.gov.
For more information on the BRFSS in general, see the BRFSS FAQs.