2008 yuarebrF 145 Number 2, iesSer

Linkage of the National

Health Interview Survey

to Air Quality Data
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All material appearing in this report is in the public domain and may be

reproduced or copied without permission; citation as to source, however, is

appreciated.

Library of Congress Cataloging-in-Publication Data

Linkage of the National Health Interview Survey to air quality data.

p. ; cm.— (Vital and health statistics. Series 2, Data evaluation and methods

research ; no. 145) (DHHS publication ; no (PHS) 2008-1345)

Authors, J. Parker, N. Kravets, T. J. Woodruff.

Includes bibliographical references.

ISBN-13: 978-0-8406-0619-8

ISBN-10: 0-8406-0619-2

1. Air pollution—Health aspects—United States—Statistics. I. Parker, J.

(Jennifer D.) II. Kravets, N. (Nataliya) III. Woodruff, T. J. (Tracey J.) IV. National

Health Interview Survey (U.S.) V. National Center for Health Statistics (U.S.)

VI. United States. Environmental Protection Agency. VII. Series. VIII. Series:

DHHS publication ; no. (PHS) 2008-1345

[DNLM: 1. Air Pollution—United States—Statistics. 2. Data Collection—United

States—Statistics. 3. Health Surveys—United States—Statistics. 4. Information

Systems—United States—Statistics. 5. Statistics—methods—United States. W2

A N148vb no.145 2008 / WA 754 L756 2008]

RA576.5.L56 2008

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2007045522

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Printed on acid-free paper.
Series 2, Number 145

Linkage of the National

Health Interview Survey

to Air Quality Data

Data Evaluation and Methods Research

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Center for Health Statistics

Hyattsville, Maryland

February 2008

DHHS Publication No. (PHS) 2008–1345
National Center for Health Statistics

Edward J. Sondik, Ph.D., Director

Jennifer H. Madans, Ph.D., Acting Co-Deputy Director

Michael H. Sadagursky, Acting Co-Deputy Director

Jennifer H. Madans, Ph.D., Associate Director for Science

Jennifer H. Madans, Ph.D., Acting Associate Director for

Planning, Budget, and Legislation

Michael H. Sadagursky, Associate Director for

Management and Operations

Lawrence H. Cox, Ph.D., Associate Director for Research

and Methodology

Linda B. Torian, Acting Director for Information Technology

Linda B. Torian, Acting Director for Information Services

Linda T. Bilheimer, Ph.D., Associate Director for Analysis

and Epidemiology

Charles J. Rothwell, M.S., Director for Vital Statistics

Jane E. Sisk, Ph.D., Director for Health Care Statistics

Jane F. Gentleman, Ph.D., Director for Health Interview

Statistics

Clifford L. Johnson, M.S.P.H., Director for Health and

Nutrition Examination Surveys

Office of Analysis and Epidemiology

Linda Bilheimer, Ph.D., Associate Director

Diane Makuc, Dr.P.H., Associate Director for Science

Pauline Mendola, Ph.D., Chief, Infant, Child, and Women’s

Health Studies Branch

Christine Cox, M.A., Chief, Special Projects Branch

Amy Bernstein, Sc.D., Chief, Analytic Studies Branch

James Lubitz, M.A., Acting Chief, Aging and Chronic

Disease Statistics Branch

Richard Klein, M.A., Acting Chief, Health Promotion

Statistics Branch
Contents
 

Abstract ................................................................................................. 1 
 

Introduction .............................................................................................. 1 
 

Background .............................................................................................. 1 
 

Linkage of NHIS to Air Quality Data ......................................................................... 2 
 

Data Files Used for Linkage............................................................................... 2 
 

Linkage Methods........................................................................................ 4 
 

Description of Linked Data Files ............................................................................. 5 
 

Methods ............................................................................................... 6 
 

Results ................................................................................................ 6 
 

Discussion ............................................................................................... 7 
 

References ............................................................................................... 8 
 

Text Tables

A.	 Median and interquartile range of the number of pollution monitors used in exposure estimation, by geographic linkage
 

method and pollutant: National Health Interview Survey, 2005 ............................................... 7 
 

Detailed Tables

1.	 Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for PM10, by 
 

geographic linkage method and survey year: United States, 1987–2005......................................... 9 
 

2 Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for SO2, by 
 

geographic linkage method and survey year: United States, 1987–2005......................................... 9 
 

3.	 Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for NO2, by 
 

geographic linkage method and survey year: United States, 1987–2005........................................ 10 
 

4.	 Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for CO, by
 

geographic linkage method and survey year: United States, 1987–2005........................................ 10 
 

5.	 Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for PM2.5, by 
 

geographic linkage method and survey year: United States, 1999–2005........................................ 11 
 

6.	 Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for O3, by 
 

geographic linkage method and survey year: United States, 1987–2005........................................ 11 
 

7.	 Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for PM10, by geographic
 

linkage method and respondent characteristic: United States, 2005 ........................................... 12 
 

8.	 Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for SO2, by geographic
 

linkage method and respondent characteristic: United States, 2005 ........................................... 13 
 

9.	 Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for NO2, by geographic
 

linkage method and respondent characteristic: United States, 2005 ........................................... 14 
 

10.	 Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for CO, by geographic
 

linkage method and respondent characteristic: United States, 2005 ........................................... 15 
 

11.	 Percentage and standard errors (SE) of NHIS respondents linked to annual EPA monitoring data for PM2.5, by 
 

geographic linkage method and respondent characteristic: United States, 2005 .................................. 16 
 

12.	 Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for O3, by geographic
 

linkage method and respondent characteristic: United States, 2005 ........................................... 17 
 

iii
13.	 Median and interquartile range of PM10 exposure (μg/m3

) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and survey year: United States, 1987–2005........................................ 18 
 

14.	 Median and interquartile range of SO2 exposure (ppb) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and survey year: United States, 1987–2005........................................ 18 
 

15.	 Median and interquartile range of NO2 exposure(ppb) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and survey year: United States, 1987–2005........................................ 19 
 

16.	 Median and interquartile range of CO exposure (ppm) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and survey year: United States, 1987–2005........................................ 19 
 

17.	 Median and interquartile range of PM2.5 exposure (μg/m3

) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and survey year: United States, 1999–2005........................................ 20 
 

18.	 Median and interquartile range of PM10 exposure (μg/m3

) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and respondent characteristic: United States, 2005 .................................. 20 
 

19.	 Median and interquartile range of SO2 exposure (ppb) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and respondent characteristic: United States, 2005 .................................. 21 
 

20.	 Median and interquartile range of NO2 exposure (ppb) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and respondent characteristic: United States, 2005 .................................. 22 
 

21.	 Median and interquartile range of CO exposure (ppm) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and respondent characteristic: United States, 2005 .................................. 23 
 

22.	 Median and interquartile range of PM2.5 exposure (μg/m3

) for respondents linked to annual EPA monitoring data, by
 

geographic linkage method and respondent characteristic: United States, 2005 .................................. 24 
 

iv
Objective

This report describes the linkage

between the National Health Interview

Survey (NHIS) and air monitoring data

from the U.S. Environmental Protection

Agency (EPA). There have been few

linkages of these data sources, partly

because of restrictions on releasing

geographic detail from NHIS on

public-use files in order to protect

participant confidentiality.

Methods

Pollution exposures for NHIS

respondents were calculated by

averaging the annual average exposure

estimates from EPA air monitors both

within 5, 10, 15, and 20 miles of the

respondent’s block-group location

(which is available on restricted NHIS

data files) and by county of residence.

The 1987–2005 linked data files—

referred to as NHIS-EPAAnnualAir—

were used to describe the percentage

of NHIS respondents linked and the

median exposures by linkage method,

survey year, and pollutant. Using the

2005 NHIS-EPAAnnualAir data file, the

percentage linked and median

exposure were described by

respondent characteristics, linkage

method, and pollutant.

Results

Many decisions were made to define

pollution exposures for NHIS

respondents, including monitor

selection, location assignment for NHIS

respondents, and geographic linkage

criteria. Geographic linkage criteria for

assigning area-level exposure estimates

affected the percentage and

composition of respondents included in

the resulting linked sample. Median

exposure estimates, however, were

similar among geographic linkage

methods.

Conclusion

NHIS-EPAAnnualAir data files for

1985 through 2005 are currently

available to users in the NCHS

Research Data Center.

Keywords: National Health Interview

Survey c air pollution c data linkage c

GIS (geographic information system)

Linkage of the National Health

Interview Survey to Air Quality

Data

by Jennifer D. Parker, Ph.D., Office of Analysis and Epidemiology;

Nataliya Kravets, M.A., NOVA Research Company, Northrop

Grumman CITS II Contractor; Tracey J. Woodruff, Ph.D., M.P.H.,

U.S. Environmental Protection Agency and the University of

California at San Francisco

Introduction

The objective of this report is to

describe the linkage of the National

Health Interview Survey (NHIS) with

air monitoring data obtained from the

U.S. Environmental Protection Agency

(EPA). This report is divided into

several sections. The first two sections

introduce and give background

information concerning the linkage. The

third section describes the

methodological issues that arose during

the linkage of the two national data

systems, including characteristics of the

input datasets, selection of monitors

from the EPA data for inclusion, and the

assignment of pollution exposures for

each respondent. The fourth section

describes the resulting linked data files,

and the fifth section summarizes the

report and presents conclusions. Because

NHIS respondents do not necessarily

live near air pollution monitors and air

pollution monitors are not all located

near NHIS respondents, the resulting

linkage necessarily excludes some

survey respondents and some air

monitors. Consequently, both the

characteristics of the sample and the

overall exposure estimates are affected

by linkage decisions.

As the need to study the effects of

environmental pollutants on human

health increases, opportunities to

combine existing data sources should be

explored. Understanding the linkage

issues will enhance the strengths and

mitigate the limitations of analyses

using the NHIS-EPAAnnualAir data

files, and it may also improve future

linked data files.

Background

To date, only a few research papers

have used EPA air pollution monitoring

data linked to NHIS to examine health

outcomes; Ostro combined NHIS data

from the late 1970s with corresponding

estimates of air pollution to examine

respiratory morbidity and work-loss

days (1–5). Linkages between EPA data

and the Centers for Disease Control and

Prevention’s National Center for Health

Statistics (NCHS) National Health and

Nutrition Examination Surveys

(NHANES) have also been used

foranalytic studies of cardiovascular (6)

Nataliya Kravets’ work on this project was funded by the Office of the Assistant Secretary for Planning

and Evaluation, ASPE, SP 05–039, Data Linkage for Environmental Health Policy. This report was edited

by Demarius V. Miller and Megan M. Cox, CDC/CCHIS/NCHM/Division of Creative Services,

Writer-Editor Services Branch, and typeset by Jacqueline M. Davis, CDC/CCHIS/NCHM/Division of

Creative Services.

Page 1
Page 2 [ Series 2, Number 145

and pulmonary (7–8) outcomes. NCHS

vital statistics data have been linked to

county level air quality data to examine

daily mortality (9–14) and perinatal

outcomes (15–18).

In 1977, NCHS published

‘‘Statistics Needed for Determining the

Effects of the Environment on Health,’’

which included many recommendations

on how to use data efficiently to relate

environmental factors to health effects

(19). These recommendations included

the extension and broadening of NCHS

surveys to include measures of

environmental exposures and the

facilitation of epidemiological studies

using available data. A subobjective was

to facilitate and support the pooling and

interpretation of data across institutions

concerned with environmental health.

Over the last 30 years, many

biomonitoring measurements have been

collected by NHANES programs and

used for research and policy, and some

studies linking ambient exposures to

health have been conducted.

Linkages between NCHS surveys

and EPA monitoring data, however, have

been hindered by several factors,

including limited geographic detail

available on public-use files,

noncompatible geographic units for

linkage, and the lack of correspondence

between respondent locations and

monitor locations. Health data systems

at NCHS are designed to provide

national estimates for health outcomes,

conditions, and risk factors. Disclosure

of detailed information on individual

records may lead to violations of data

confidentiality; furthermore, the sample

sizes for subnational geographic units

are often too small to provide

statistically reliable estimates. As a

result, geographic information in the

large national data systems is limited on

public-use files and restricted on

in-house files. Currently the public-use

NHIS data files provide only one

geographic identifier, REGION, which is

coded into four categories: Northeast,

Midwest, South, and West. Earlier years

of NHIS released information on large

Metropolitan Statistical Areas or large

states (20).

Even with the more detailed

geography on in-house NHIS data files,

combining these files and EPA data

systems is complicated by incompatible

geographic units. Individual monitor

measurements originate at a particular

site and have been geocoded to latitude

and longitude (21). NHIS, on the other

hand, is limited by the availability and

quality of geocodes. Although geocodes

can be assigned at various geographic

levels, more NHIS respondents can be

coded to their U.S. Census Bureau block

group of residence than to smaller units.

Statistical approaches for analyzing

misaligned data—that is, data with

information for different levels of

geography—have been described (22).

One straightforward method is to

aggregate estimates using geographic

information common to both data sets.

For example, county of residence for

NHIS respondents and the average

exposure for a county are easily

combined.

Even with availability of location

information and aligned estimates,

survey data and monitoring data may

not be collected at the same locations;

that is, not all survey respondents reside

near air pollution monitors, and not all

pollution monitors are near survey

respondents. This lack of overlap is not

surprising because the data sources are

collected for different purposes. Air

monitors are used for regulatory

purposes (23), whereas NHIS is

designed to be a nationally

representative sample of the U.S.

civilian noninstitutionalized population

(20). This lack of overlap means that

health estimates from the resulting file

no longer meet the NHIS feature of

‘‘nationally representative,’’ and

exposure estimates are based on less

coverage than those using the original

collection of monitors.

Linkage of NHIS to

Air Quality Data

Data Files Used for

Linkage

The National Health Interview

Survey

NHIS is a nationally representative

sample of the civilian,

noninstitutionalized population

conducted continuously by NCHS (20).

Data are collected through in-person

interviews. The structure of the survey

instrument has changed from 1987 to

2005. Since the major redesign of NHIS

in 1997, questions from the Family Core

Questionnaire are asked about each

person in the family and compiled into

the NHIS person file. In addition, a

sample adult and a sample child from

each family with children are randomly

selected, and additional questions for

this adult and child are asked.

Information for the randomly selected

adult and child from each family are

contained in the separate sample adult

and sample child files. Although

respondent characteristics described in

this report are from the person file,

additional information from public-use

files, including the sample adult and

sample child files, can be combined

with the linked data files for analytic

studies.

Many households in NHIS are

missing sufficient information for

accurate coding at all levels of

geography. Annually created in-house

NHIS files, available under restricted

conditions to NCHS staff and to other

users of the Research Data Center

(RDC) (24), include state and county

codes. These codes have allowed

researchers to link NHIS to contextual

information from other sources, such as

the Area Resource File (25). Special

NHIS files geocoded to U.S. Census

Bureau blocks and block groups have

been created and are available only

through the RDC for all users, including

NCHS staff. Files with geocoded

household location, used in the
Series 2, Number 145 [ Page 3

assignment of block and block-group

identifiers when available, are not

currently retained by NCHS.

U.S. Census Bureau block groups,

the primary geographic units used to

link data files, are geographic

subdivisions of census tracts; their

primary purpose is to provide a

geographic summary unit for census

block data. A block group comprises a

reasonably compact and contiguous

cluster of census blocks. Each census

tract contains a minimum of one block

group and may have a maximum of nine

block groups. Although the number of

people in census block groups averages

about 1,500, the minimum is about 600

people and the maximum is about 3,000

people (26). Because the geographic

information available for block groups

was different between the years prior to

1995 and the years starting with 1995,

geographic internal points (unweighted

coordinates at the center of the block

group) of block groups were used for

the 1987–1994 NHIS, and coordinates

of the population-weighted centroids

were used for the 1995–2005 NHIS;

these locations are very close for most

NHIS locations (see Block-group

centroid under Linkage Methods).

EPA Annual Air Pollution

Monitoring Data

The EPA has set national air quality

standards for principal air pollutants,

often referred to as criteria pollutants.

These pollutants are ozone (O3),

nitrogen dioxide (NO2), sulfur dioxide

(SO2), particulate matter less than 10

microns in diameter (PM10) and

particulate matter less than 2.5 microns

in diameter (PM2.5), carbon monoxide

(CO), and lead (Pb) (23). Each of these

pollutants is monitored to summarize the

current status of the air quality. The

collection times, monitor locations, and

the reported measures vary among

pollutants because they are collected for

regulatory rather than research purposes

and because the properties of the

pollutants differ.

The Air Quality System (AQS)

database provides annual averages of air

monitoring data, which are ambient

concentrations of criteria and hazardous

air pollutants at monitoring sites,

primarily in cities and towns (20). The

AQS database is updated by the EPA

daily, primarily by the staff of state and

local environmental agencies that

measure ambient concentrations of

criteria air pollutants at several thousand

monitoring sites throughout the United

States. Each month, the EPA extracts a

summary of the measurements recorded

at each air monitoring station (the

highest value in a year, the average,

etc.) and updates AirData.

For the purposes of this project,

monitor-specific annual averages were

extracted from the AQS using the

Annual Summary Web pages (21).

Although the individual observations for

each monitor are available, the annual

arithmetic averages calculated by the

EPA were used. For this initial linkage,

using these averages was considered

preferable to calculating these or other

metrics directly from the raw data for

several reasons: they were calculated

using EPA methodology, are readily

obtained, and are more easily replicated.

However, even using the annual

averages, several variables were

downloaded from the system for each

monitor (defined more fully in the EPA

documentation [21]) to identify monitors

for inclusion, including those listed

below.

1. MONITORID—unique monitor

identifier that comprises the

following:

a.	 STATE—location of

monitor.

b. COUNTY—location of

monitor.

c.	 PARAMETERCD—

identifier for the pollutant

exposure collected at the

monitor.

d. SITE ID—site

identification is used to

obtain information on the

location of the pollution

monitor.

e.	 POC—parameter

occurrence code, which is

used to distinguish

monitors collecting

information at the same

site for the same pollutant.

2. PCNT_OBS—the percentage of

data values collected relative to

that expected for a particular

pollutant and monitor.

3. OBS_CNT—the number of

observations.

4. EXCEPTIONAL DATA

FLAG—indicates whether

something has occurred locally

that could have affected the

annual average.

5. ARITH_MEAN—the annual

average.

6. YR_WTD_ARITH_MEAN—the

annual average based on

combining four quarterly

averages. This is available for

PM10 and PM2.5.

7. INTERVAL_CODE—used to

determine how frequently

pollution measurements were

obtained and how they were

reported.

Using SITE ID, additional

information about the monitoring sites

(including location parameters) was

extracted from the site information

pages (21), including: LATITUDE,

LONGITUDE, and DATUM CODE

(indicating the geographic coordinate

system used to code latitude and

longitude).

For the purpose of this project, the

following steps were performed:

1. The small number of monitors

outside the 50 states and the

District of Columbia were

excluded.

2. The monitors were limited to

those that collected data for Pb,

total suspended particulates (TSP,

a proxy sometimes used for

PM10), O3, CO, SO2, NO2,

PM10, and PM2.5.

3. Experimental monitors were

excluded (POC > 4, a criterion

for experimental monitors).

4. Multiple annual averages from

some monitors were included in

the AQS file because the

monitors report different annual

averages using different sets of

the raw measurements for

regulatory purposes. In the case

of multiple monitor entries, the

annual average that included all

recorded measures

(EXCEPTIONAL DATA FLAG
Page 4 [ Series 2, Number 145

= 0, no events recorded, or 2,

including all exceptional events)

was retained. When exceptional

events take place at a monitor’s

location, such as a forest fire,

multiple ways of measuring

pollution for regulatory purposes

exist: including exceptional

events, excluding them, including

some types of events and

excluding others, etc. Thus, this

step also eliminated multiple

records for the same monitor.

5. The annual averages were

limited to those that were based

on data collected under specified

reporting intervals (as indicated

by INTERVAL_CODE). Gaseous

pollutants were typically reported

hourly each day, whereas

particulates were often reported

as daily averages every 3 or 6

days. Specifications for selected

pollutants were as follows:

a.	 For SO2, 1-hour intervals

were used. A very small

number of monitors

collected measurements at

5-minute intervals, and

they were removed.

b. For NO2, 1-hour intervals

were used.

c.	 For CO, 1-hour intervals

were used.

d. For O3, daily maximums

from 1-hour intervals and

8-hour running average

intervals were used as

separate variables.

e.	 For PM10, 1-hour, 24-hour,

and/or 24-hour block

average (a daily average of

1-hour measurements)

intervals were used

interchangeably.

f.	 For PM2.5, 1-hour, 24-hour,

and/or 24-hour block

average intervals were used

interchangeably.

6. Monitors with missing annual

arithmetic averages were

excluded.

7. On the basis of PCNT_OBS and

OBS_CNT, monitors with fewer

than 75 percent of the expected

number of observations were

excluded; after examining

missing data patterns, monitors

were excluded if either

PCNT_OBS or OBS_CNT was

missing.

8. Both PM10 and PM2.5 may be

measured under standard

conditions (i.e., 25 +C, 1

atmosphere), prevailing local

conditions, or both. This

difference originates for political

purposes and poses a

comparability problem. For

PM2.5, only local data were used,

which are much more prevalent

than standard data. For PM10,

standard data was used in

preference to local data if both

were available at the same site,

and when sites provided only

local data, a county-specific

correction (typically 5 percent or

less) was used so that the value

approximated standard conditions

(personal communication with

Abt Associates; available upon

request).

9. After the preceding steps, if there

were more than one monitor for

a particular pollutant at a site,

the annual average was retained

for one monitor—most often the

monitor with the highest

percentage of observations

collected (PCNT_OBS).

The annual exposure estimates for

O3 need to be further qualified. In

cooler months, O3 levels drop

considerably. As a result, not all states

require O3 monitoring for the entire

year, which leads to annual averages

that are based on differing time periods;

typically the monitoring season is May

through September, but it varies (27).

Although this system is adequate for

regulatory purposes, its use could bias

epidemiological associations and

surveillance without additional

purpose-specific qualifications.

Linkage Methods

Pollution exposure values were

assigned to individual NHIS records by

combining all annual averages for each

pollutant from monitors within a

specified distance and within the same

county of the respondent. Distances

between NHIS participants and the air

quality monitors were calculated using

the latitude and longitude assigned to

the block group of residence of NHIS

participants and the latitude and

longitude of the EPA monitors. Using

these distances to identify nearby

monitors, annual pollution estimates

within 5, 10, 15, and 20 miles of the

NHIS respondents’ block group were

calculated. Annual pollution estimates

for each county were also calculated and

assigned to NHIS participants by county

of residence. As a result, pollution levels

for a particular pollutant are assigned to

NHIS participants in multiple ways in

the NHIS-EPAAnnualAir data files.

Distance Calculations

Distance Formula—The Great

Circle Distance Formula (28) was used

in this research to calculate distances.

Given that the calculation of the

distance affects the identification of

monitors near the block-group centroid,

the choice of formula might influence

distance-based exposure calculations.

Although distance formulas are known

to be approximations, for the relatively

short distances needed for exposure

assignment, the Great Circle Distance

Formula likely provides reasonable

measures for use in this research.

Geodetic datum—Another issue

addressed when calculating distances

was the unknown datum of the

geographic coordinate system, that is,

the system used to assign location.

Latitude and longitude can be assigned

to locations using a variety of systems

that use different reference points and

assume different conditions for Earth’s

surface and size (28). Importantly, the

same latitude and longitude values can

identify different points on Earth’s

surface if they are assigned using

different geographic coordinate systems.

However, if the geographic coordinate

system is known for a particular

location, coordinates can be transformed

from one system to another. In the EPA

monitor dataset, about 80 percent of the

records were missing DATUM CODE,

which is used to identify the system

used to assign latitude and longitude.
Series 2, Number 145 [ Page 5

The remaining monitors had codes that

indicated that the latitude and longitude

coordinates had been recorded using one

of three primary geodetic systems:

North American Datum 1983, North

American Datum 1927, or World

Geodetic System of 1984. Although

knowing how the coordinates were

assigned to a location is essential for

having accurate maps, what was not

known during this research was whether

there would be an effect of using

coordinates derived from different

geographic coordinate systems on

distance calculations for the short

distances (20 miles or less) needed for

this exposure assessment. To examine

this issue of geodetic datum, a

sensitivity analysis was performed by

reassigning the coordinate system of the

block groups and recalculating distances.

The results indicated that any potential

miscalculation was likely to be

negligible for the distance calculations

needed for this project (details available

upon request.)

Block-group centroid—This project

next examined how distances that are

based on block-group centroids

approximate distances that are based on

residence. Using a subset of the

2004–2005 intermediate NHIS data file

with known location information by

residence (these files were in the

process of being geocoded at the time of

this analysis, but the residential

information has subsequently been

destroyed), the (unweighted) distribution

of the distances between NHIS family

locations and the block-group centroid

were examined. This process was

repeated to examine both the geographic

internal point (the approximate location

of the physical center of the block

group) and the population-weighted

centroid (the approximate location of the

center weighted by population—in other

words, the center where people live).

About 95 percent of NHIS families were

within 2 miles of the assigned

block-group centroid, whether the

centroid was defined by the populationweighted centroid or the geographic

internal point. The distribution of

distances for the population-weighted

centroid was shifted to the left,

indicating shorter distances.

Exceptionally large differences between

the population-weighted centroid and the

geographic internal point were identified

in Alaska and Hawaii, suggesting that

block-group assignment is a better

indicator of residential location for

respondents in the 48 contiguous states.

For these data files, the populationweighted centroid of the block group

and the geographic internal point were

available for the 1995–2005 NHIS.

Because the U.S. Census Bureau

definitions were different for earlier

years, only the geographic internal point

was available prior to 1995. Exposure

assignments using either centroid are

likely to be similar. Nevertheless, the

population-weighted centroid of the

block group was used as the location for

the 1995–2005 NHIS and the

geographic internal point for earlier

years.

Exposure Assignment

Using the distances between the

latitude and longitude of the block

group of residence of the NHIS

participant and the latitude and

longitude of the air quality monitor,

pollution exposures for each participant

were estimated by averaging all annual

averages from monitors located within

5, 10, 15, and 20 miles from the

block-group centroid. Unweighted and

distance-weighted averages were

calculated (distance-weighted averages

were calculated using the inverse of the

squared distance between the centroid

and the monitor as a weight).

In addition to the distance-based

pollution exposures, county-specific

annual exposure averages were

calculated by averaging the annual

averages for each monitor in each

county and were assigned to individual

NHIS records by county of residence.

Although the monitor information on the

EPA website (21) is coded to the most

recent set of county Federal Information

Processing Standards (more commonly

known as FIPS) codes (currently 2000)

regardless of the year the monitoring

data were collected, NHIS data files are

not automatically updated. For the years

in this report, FIPS county identifiers for

the EPA monitor information were

recoded to be compatible with NHIS.

Exposure Variables

Monitor-specific arithmetic annual

average exposures were collected for the

following: PM (μg/m3

10 ), overall and

quarterly weighted; PM2.5 (μg/m3

),

overall and quarterly weighted; CO

(ppm); SO2 (ppm); NO2 (ppm); O3

(ppm), overall and average of running 8

hour measurements; Pb (ppm); and TSP

(μg/m3

).

For each respondent, the following

variables were created from the annual

monitor averages for each pollutant

above:

1. Average of annual exposures of

monitors within the county.

2. Number of monitors used to

calculate exposure within the

county.

3. Average of annual exposures of

monitors within 5, 10, 15, and

20 miles of the respondent’s

block group (four variables).

4. Average of annual exposures of

monitors within 5, 10, 15, and

20 miles of the respondent’s

block group, inverse distance

weighted (four variables).

5. Number of monitors within 5,

10, 15, and 20 miles of the

respondent’s block group (four

variables).

6. Distance to nearest monitor.

7. Annual exposure at nearest

monitor.

Currently, the 1985–2005

NHIS-EPAAnnualAir data files are

available as statistical analysis software

(also known as SAS) data files for

external users in the RDC; 1985 and

1986 data years have exposure

information for fewer respondents and

are not described in this report.

Description of Linked

Data Files

To evaluate the linked files, the

NHIS-EPAAnnualAir data files are

described in terms of the percentage of

NHIS respondents linked to six of the

linked pollutants using different

alternatives for exposure
Page 6 [ Series 2, No. 145

assignment: PM10 (quarterly weighted),

PM2.5 (quarterly weighted), CO, SO2,

O3, and NO2. The median and the

interquartile range of pollution exposure

are shown for all pollutants except O3,

because of its different monitoring

schedule (27).

Methods

Percentage Linked

The percentage of NHIS

respondents linked to each pollutant was

calculated for selected geographic

linkage methods (5 mile, 10 mile, 20

mile, and county) by survey year using

the 1987–2005 NHIS-EPAAnnualAir

data files. Using the 2005 NHISEPAAnnualAir data file, percentages

were estimated for each geographic

linkage method by NHIS subgroups,

defined by poverty status (29), Hispanic

origin and race, age, health status,

region, and urbanization level of the

county of residence (30).

Because many percentages are not

independent, the respondents, for

example, with a 5-mile exposure

estimate are included among those with

a 20-mile exposure estimate, and many

respondents with an exposure estimate

for PM10 are likely included among

those with an exposure estimate for

NO2; statements that refer to lower or

higher percentages across geographic

linkage methods or across pollutants are

not based on statistical tests. Conversely,

percentages between survey years or

respondent characteristics are assumed

independent, and tests of differences

were based on approximate z statistics

using the standard errors of each

percentage to estimate the standard error

of the difference (31); statements that

refer to lower or higher percentages are

based on a critical value of 1.96 for a

two-sided z test at the 0.05 level with no

adjustment for multiple comparisons.

Lack of comment does not mean that

percentages were compared and deemed

not statistically significant.

Exposure Estimates

The median (50th percentile) and

the interquartile range (25th and 75th

percentiles) of the estimated annual

average pollution exposures were

estimated for selected geographic

linkage methods (5 mile, 20 mile, and

county) by survey year using the

1987–2005 NHIS-EPAAnnualAir data

files. These percentiles were also

estimated for the geographic linkage

methods by NHIS subgroups described

above using the 2005 NHISEPAAnnualAir data files.

For these percentile calculations, the

exposure variables calculated without

inverse-distance weighting were used.

That is, this research utilized the

20-mile exposure variables that were

calculated by combining annual

averages from all monitors within 20

miles, without regard to distance from

the respondent’s block group of

residence. Differences in exposure

estimates between the 5-mile and

20-mile variables are greater than the

corresponding differences between the

5-mile and 20-mile inverse-distance

weighted variables.

Sets (median and interquartile

range) based on fewer than 100 total

respondents or fewer than 25

respondents above the 75th percentile or

below the 25th percentile are not shown.

Statements that refer to lower, higher, or

similar medians are not based on

statistical tests; statistical methods for

percentiles of geographically clustered

exposures within complex surveys are

not fully developed.

Because of the clustering inherent

in complex survey designs, standard

errors were calculated in SUDAAN

(32). All estimates were weighted by

NHIS survey weights to approximate the

relative distributions and exposures in

the population represented by the linked

sample. Because of the varying

percentages of linked records by

pollutant and geographic linkage

methods, the appropriateness of

statistical methods that use the NHIS

design (e.g., weights, strata, primary

sampling units) for these linked data

files has not been confirmed.

Results

Percentage of NHIS

Respondents Linked to Air

Quality data

For each pollutant, Tables 1–5 show

the number and survey-weighted

percentage of NHIS respondents linked

by survey year as well as varying

distances between the block group and

the monitors. Using 2005 data as an

example, the percentage linked for

exposures defined by a 5-mile radius

ranged from 17 percent for SO2 to

36 percent for PM2.5, and the percentage

linked for a 20-mile exposure radius

increased to a range of 55 percent for

NO2 to 80 percent for PM2.5. The

percentage of respondents linked to

pollution exposure varied by pollutant,

geographic linkage method, and survey

year. For each pollutant and each survey

year, a large percentage of NHIS

respondents were not assigned an

exposure estimate and could not be

included in association studies of health

and air pollution. This limitation is

particularly pronounced for exposures

defined by the 5-mile radius, where

(with the exception of PM2.5 and PM10

for the mid-1990s NHIS) fewer than

30 percent of respondents are linked.

Although PM2.5 estimates are

unavailable for earlier years, in recent

years, more NHIS respondents had

exposure data for PM2.5 than for other

pollutants.

Using the 2005 NHISEPAAnnualAir file, Tables 6–10 show

the number and survey-weighted

percentage of NHIS respondents linked

by varying distances from the block

group to the monitor for different

respondent characteristics. Generally, a

higher percentage of poor respondents

(compared with near-poor and nonpoor

respondents—particularly for 5-mile

exposures), non-Hispanic black

respondents (compared with nonHispanic white respondents), Hispanic

respondents (compared with nonHispanic respondents), and, to a lesser

degree, younger respondents (compared

with older respondents) are linked to

pollution exposure information, although

these relationships were not observed,
Series 2, Number 145 [ Page 7

nor statistically significant, for all

pollutants and all linkage methods.

Associations between linkage and health

status were weak. More respondents in

the large central cities and in the West

were linked compared with those in

other areas. With some exceptions,

within a particular subgroup, patterns

were generally similar by geographic

linkage method even if the percentages

differed.

Percentages and standard errors

calculated without survey weights were

generally similar to those presented (not

shown). Differences between the

survey-weighted and unweighted

estimates were generally larger for

5-mile linkages compared with linkages

for greater radii, and they were also

larger for population subgroups

(particularly those in less urban areas)

with lower linkage percentages. Most

relative differences were lower than

10 percent (not shown).

Exposure Estimates

Tables 11–15 summarize the

survey-weighted median and

interquartile range of the exposures by

survey year and the varying distances

between the respondent’s block group of

residence and the exposure monitors.

Pollution levels have generally

decreased over time. Median pollution

levels appear similar by geographic

linkage method; slightly lower values

were reported for NO2 and SO2 for

larger geographic areas. PM2.5 estimates

appear higher for 5-mile exposure

estimates than for other geographic

linkage methods.

Tables 16–20 summarize the

survey-weighted median and

interquartile range of the exposure

estimates by selected respondent

characteristics and by varying distances

between the respondent’s block group of

residence and the exposure monitors

using the 2005 EPAAnnualAir file.

Generally, median exposures were

similar for poor respondents compared

with near-poor and nonpoor respondents,

although there were exceptions.

Geographic differences (e.g., by region

and urbanization level of the county)

were larger than differences for other

respondent characteristics. Median

exposures among respondents in the

West were highest for some pollutants

(e.g., CO) but lowest for others (e.g.,

PM2.5).

The median numbers of monitors

used to estimate exposures in 2005 are

given in Table A. Relatively few

monitors are used in the estimation of

exposures for most respondents,

particularly for the 5-mile and 10-mile

exposure measures. On the other hand,

for the 20-mile and county level

exposures measures, the 75th percentiles

of the number of monitors used for

estimation are four or higher for nearly

all of the pollutants examined. The

estimates presented in this report are, for

the most part, within 5 percent of those

calculated using the inverse distanceweighted exposure variables, the

variables assigned by combining annual

monitor-specific averages weighted by

their distance from the block-group

center. Differences were larger for the

20-mile exposures compared with the

5-mile exposures, which is likely due to

the relatively few monitors used in the

estimation of 5-mile exposure for most

respondents (Table A).

Discussion

Numerous decisions are needed to

link national surveys to EPA’s air

monitoring data, including the selection

of monitors, the calculation of distances,

the assignment of geographic location

for survey respondents, and the

geographic area over which to estimate

exposure. What is important to note is

that the number of available survey

respondents for analysis of exposurehealth relationships with linked data

depends on the geographic area over

which exposures are calculated—the

larger the area, the more respondents are

included. When more precise exposure

estimates are needed, the number of

respondents will decrease and the

demographic composition of the sample

will change. Depending on the study,

differences in the sample could affect

resulting associations (33). Nevertheless,

the availability of these linked data files

provides an opportunity to investigate

nationwide, if not nationally

representative, associations between air

quality and health. Among other

benefits, these investigations will likely

lead to improvements in future linkage

methodology between these data

sources.

The best analytic methods for these

data are unknown. Two statistical issues

are particularly important. First, the

combination of these data sources leads

to a linked file that is a subset of the

nationally representative survey; what is

unknown is whether the survey weights

are appropriate for use with the

subsetted data or whether the resulting

file should be analyzed unweighted and

considered a clustered convenience

sample. Second, because block-group

centroids are used for assigning

exposure, all respondents within a block

group are assigned the same exposure

value (or no exposure value.) The effect

of the additional clustering on standard

errors of summary statistics for these

exposure measures (e.g., means and

percentiles) within the NHIS clustered

complex survey design is unknown.

Statistical survey research is needed to

understand the use of survey weights

and design-based methods for these

linked data files.

Table A. Median and interquartile range of the number of pollution monitors used in

exposure estimation, by geographic linkage method and pollutant: National Health

Interview Survey, 2005

Pollutant 5-mile 10-mile 20-mile County

Carbon monoxide........... 1(1,1) 2(1,3) 2(1,5) 2(1,4)

Sulfur Dioxide ............. 1(1,1) 1(1,2) 2(1,4) 1(1,3)

Nitrogen Dioxide ........... 1(1,1) 1(1,2) 2(1,5) 2(1,4)

PM10 .................. 1(1,2) 1(1,3) 3(1,5) 1(1,6)

PM2.5 .................. 1(1,2) 2(1,3) 3(2,6) 2(1,4)

NOTES: Percentiles calculated using survey weights. PM10 is particulate matter less than 10 microns in diameter; PM2.5 is

particulate matter less than 2.5 microns in diameter.
Page 8 [ Series 2, Number 145

NHIS is a large household survey

that collects information on many health

indicators potentially associated with air

quality, including asthma, cardiovascular

health, and activity limitations. The data

contain respondents of many racial and

ethnic backgrounds with varying levels

of socioeconomic status. Trends for

many health indicators are available for

many years. Although the cross-sectional

design of the survey and the inability to

determine clearly the time of exposure

may limit the understanding of many of

these relationships, the breadth and size

of the linked data files suggest

opportunity.

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Series 2, Number 145 [ Page 9

Table 1. Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for PM10, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

5-mile 10-mile 20-mile County

Number of

Survey survey

year respondents Number Percent SE Number Percent SE Number Percent SE Number Percent SE

1987 ................ 122,859 17,590 13.9 0.8 34,836 27.4 1.1 51,966 41.7 1.3 39,747 31.7 1.3

1988 ................ 122,310 24,682 19.3 0.8 45,481 36.6 1.2 69,297 56.4 1.3 54,040 43.5 1.5

1989 ................ 116,929 34,806 29.1 1.0 58,665 49.7 1.3 77,505 66.5 1.4 65,550 55.5 1.3

1990 ................ 119,631 39,358 32.3 0.9 64,712 54.1 1.2 83,662 70.5 1.3 71,815 60.0 1.4

1991 ................ 120,032 40,724 33.3 0.9 66,619 55.1 1.1 86,068 71.8 1.2 74,605 62.0 1.3

1992 ................ 120,700 42,620 34.6 1.0 68,582 56.4 1.3 87,179 72.3 1.4 76,928 63.5 1.5

1993 ................ 109,671 39,514 35.3 1.0 64,271 58.2 1.3 80,922 73.8 1.4 71,551 65.0 1.6

1994 ................ 116,179 43,094 36.6 1.0 68,852 59.2 1.3 86,337 74.8 1.3 75,958 65.4 1.5

1995 ................ 102,467 41,382 38.5 0.8 65,247 61.3 0.9 80,728 77.7 0.9 70,061 66.2 1.0

1996 ................ 63,402 24,158 35.5 1.0 39,523 59.8 1.2 49,171 76.0 1.1 41,985 63.6 1.3

1997 ................ 103,477 38,866 35.3 0.7 63,776 58.8 0.8 80,334 76.1 0.9 68,768 63.5 1.0

1998 ................ 98,785 34,885 32.7 0.7 57,925 55.4 0.8 74,069 73.1 0.9 62,321 59.8 1.0

1999 ................ 97,059 30,815 28.8 0.7 52,740 51.0 0.8 70,100 69.8 0.9 56,657 54.5 1.0

2000 ................ 100,618 31,362 27.8 0.7 55,442 51.0 0.8 72,837 69.9 0.9 57,577 53.1 0.9

2001 ................ 100,760 31,195 27.3 0.7 53,909 49.2 0.9 72,017 68.4 1.0 58,271 52.7 1.0

2002 ................ 93,386 28,610 27.0 0.8 50,601 49.5 0.9 67,098 68.8 1.0 54,904 54.0 1.0

2003 ................ 92,148 27,509 26.0 0.8 48,458 47.5 0.9 64,282 66.3 0.9 51,755 50.9 0.9

2004 ................ 94,460 27,286 25.2 0.7 48,276 46.4 0.8 65,609 66.5 0.9 52,922 50.9 0.9

2005 ................ 98,649 25,705 22.9 0.6 47,797 43.8 0.8 65,967 63.6 0.9 52,100 48.2 0.9

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. PM10 is particulate matter

less than 10 microns in diameter.

Table 2. Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for SO2, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

5-mile 10-mile 20-mile County

Number of

Survey survey

year respondents Number Percent SE Number Percent SE Number Percent SE Number Percent SE

1987 ................ 122,859 34,219 27.0 0.7 55,161 44.2 0.9 72,516 58.8 1.2 59,848 48.3 1.2

1988 ................ 122,310 31,935 25.4 0.8 55,425 44.8 1.1 75,635 61.7 1.3 62,362 50.5 1.4

1989 ................ 116,929 29,577 24.4 0.8 51,150 43.1 1.1 70,303 60.3 1.3 56,955 48.2 1.5

1990 ................ 119,631 30,321 24.5 0.7 51,644 42.8 1.0 71,407 60.0 1.2 59,224 49.3 1.4

1991 ................ 120,032 30,400 24.7 0.8 51,710 42.7 1.1 73,012 61.0 1.3 60,389 50.2 1.4

1992 ................ 120,700 29,554 23.7 0.9 50,442 41.3 1.2 72,077 59.8 1.4 59,193 48.8 1.4

1993 ................ 109,671 26,804 23.8 0.9 46,616 42.3 1.2 64,796 59.2 1.4 54,836 50.0 1.4

1994 ................ 116,179 26,934 22.5 0.8 48,252 41.0 1.0 68,098 58.6 1.4 55,198 47.3 1.4

1995 ................ 102,467 25,750 23.3 0.7 45,136 42.3 0.9 63,738 61.1 1.0 54,092 50.4 1.0

1996 ................ 63,402 14,539 21.2 0.8 26,654 40.6 1.0 39,297 60.7 1.3 34,030 50.9 1.2

1997 ................ 103,477 23,094 20.8 0.6 43,264 40.1 0.8 63,326 60.1 1.0 52,280 47.7 0.9

1998 ................ 98,785 21,350 19.9 0.6 40,749 39.4 0.8 60,461 60.0 1.0 50,620 48.5 1.0

1999 ................ 97,059 20,431 19.6 0.6 38,666 38.2 0.8 58,312 58.8 1.0 49,275 47.9 0.9

2000 ................ 100,618 20,544 18.5 0.6 40,869 38.5 0.8 61,726 59.7 0.9 49,829 46.6 0.9

2001 ................ 100,760 19,969 18.0 0.6 40,510 38.0 0.8 60,255 58.0 0.9 48,649 45.2 0.9

2002 ................ 93,386 18,969 18.6 0.6 37,596 38.2 0.9 56,367 58.9 1.0 46,207 46.5 0.9

2003 ................ 92,148 17,589 17.3 0.6 35,595 36.7 0.8 53,598 56.6 1.0 42,754 43.1 0.9

2004 ................ 94,460 17,585 16.9 0.6 35,245 35.5 0.8 54,241 56.7 0.9 42,579 42.8 0.9

2005 ................ 98,649 18,565 17.1 0.5 38,377 37.1 0.8 57,984 57.7 0.9 46,727 44.6 0.9

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. SO2 is sulfur dioxide.
Page 10 [ Series 2, Number 145

Table 3. Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for NO2, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

Number of 5-mile 10-mile 20-mile County

Survey survey

year respondents Number Percent SE Number Percent SE Number Percent SE Number Percent SE

1987 ................ 122,859 22,773 18.2 0.7 41,323 32.9 0.9 57,105 46.3 1.1 42,130 33.9 1.0
 

1988 ................ 122,310 21,271 16.8 0.7 40,457 32.6 1.0 57,170 46.9 1.2 42,144 34.2 1.1
 

1989 ................ 116,929 21,247 17.5 0.7 38,401 32.4 1.1 54,546 46.8 1.4 40,930 34.7 1.3 
 

1990 ................ 119,631 24,117 19.7 0.8 44,041 36.5 1.1 59,782 50.3 1.3 45,548 37.9 1.3 
 

1991 ................ 120,032 24,842 20.3 0.7 44,884 37.1 1.0 61,598 51.5 1.3 47,648 39.7 1.2
 

1992 ................ 120,700 23,099 18.5 0.7 42,246 34.7 1.0 59,731 49.8 1.2 45,571 37.7 1.1
 

1993 ................ 109,671 22,171 19.5 0.8 39,951 36.3 1.0 56,059 51.5 1.2 42,505 38.8 1.2
 

1994 ................ 116,179 24,209 20.3 0.8 43,518 37.3 1.1 61,157 53.0 1.3 48,719 42.1 1.3 
 

1995 ................ 102,467 23,843 20.4 0.6 41,626 37.3 0.7 57,568 53.9 0.8 47,109 42.5 0.8
 

1996 ................ 63,402 13,194 18.1 0.7 24,984 35.8 1.0 35,281 53.0 1.1 27,638 40.1 1.0 
 

1997 ................ 103,477 24,012 19.6 0.5 43,289 37.2 0.7 59,423 53.7 0.8 48,613 42.4 0.7
 

1998 ................ 98,785 22,549 19.1 0.5 41,155 36.7 0.7 57,217 53.8 0.8 46,544 42.2 0.7 
 

1999 ................ 97,059 22,844 19.7 0.5 41,128 37.5 0.7 56,552 54.4 0.8 46,802 43.5 0.8 
 

2000 ................ 100,618 24,259 19.8 0.6 43,782 38.4 0.7 59,820 55.3 0.8 49,992 44.5 0.8
 

2001 ................ 100,760 23,422 19.0 0.5 43,639 38.0 0.7 59,089 54.4 0.8 49,395 43.6 0.8
 

2002 ................ 93,386 22,182 19.8 0.5 40,594 38.5 0.7 55,574 55.7 0.8 45,777 43.9 0.8 
 

2003 ................ 92,148 20,756 18.7 0.5 38,376 36.9 0.7 53,447 54.6 0.8 43,965 42.8 0.8 
 

2004 ................ 94,460 21,193 18.8 0.5 39,808 37.4 0.7 55,621 55.4 0.8 45,263 42.9 0.7 
 

2005 ................ 98,649 22,162 19.0 0.5 41,948 37.8 0.7 57,472 55.0 0.7 48,087 43.9 0.7 
 

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. NO2 is nitrogen dioxide.

Table 4. Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for CO, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

Number of 5-mile 10-mile 20-mile County

Survey survey

year respondents Number Percent SE Number Percent SE Number Percent SE Number Percent SE

1987 ................ 122,859 37,412 29.3 0.8 58,935 47.3 1.0 75,065 61.0 1.2 62,776 50.7 1.1
 

1988 ................ 122,310 36,530 28.7 0.7 58,871 47.6 0.9 75,122 61.5 1.2 64,402 52.3 1.1
 

1989 ................ 116,929 34,863 28.8 0.8 55,740 47.3 1.0 71,967 61.8 1.3 61,139 52.2 1.3 
 

1990 ................ 119,631 34,987 28.5 0.8 56,329 47.0 1.1 72,494 61.2 1.3 60,289 50.5 1.3 
 

1991 ................ 120,032 35,621 29.1 0.7 56,896 47.2 1.0 73,375 61.5 1.3 61,429 51.3 1.2
 

1992 ................ 120,700 35,160 28.5 0.8 56,505 46.7 1.1 72,724 60.5 1.3 61,127 50.7 1.2
 

1993 ................ 109,671 32,449 28.8 1.0 52,161 47.4 1.3 67,162 61.4 1.5 56,425 51.4 1.5
 

1994 ................ 116,179 33,531 28.4 1.0 54,364 46.7 1.3 70,923 61.4 1.5 58,054 50.1 1.5 
 

1995 ................ 102,467 31,857 28.3 0.7 52,155 48.0 0.8 67,546 64.0 0.9 56,419 51.8 0.9
 

1996 ................ 63,402 19,151 27.2 0.9 31,839 47.1 1.1 41,732 63.7 1.1 34,683 51.2 1.2 
 

1997 ................ 103,477 31,998 27.4 0.6 52,722 47.0 0.8 67,998 63.2 0.9 56,629 50.5 0.8
 

1998 ................ 98,785 29,651 26.4 0.7 49,101 45.6 0.8 64,046 61.9 0.8 53,447 49.7 0.8 
 

1999 ................ 97,059 27,892 25.3 0.6 47,152 44.4 0.7 62,732 61.9 0.8 53,212 50.2 0.8 
 

2000 ................ 100,618 30,222 26.0 0.7 50,133 45.3 0.7 65,991 62.6 0.8 55,890 50.7 0.7
 

2001 ................ 100,760 28,397 24.3 0.6 49,310 44.4 0.7 64,952 61.3 0.8 55,138 49.8 0.7
 

2002 ................ 93,386 26,213 24.2 0.6 45,170 43.9 0.8 60,279 61.4 0.8 50,579 49.5 0.7 
 

2003 ................ 92,148 25,051 22.9 0.6 42,782 41.7 0.8 57,325 58.9 0.8 48,254 47.4 0.8 
 

2004 ................ 94,460 24,945 22.5 0.6 43,453 41.9 0.7 59,389 60.2 0.8 49,586 48.2 0.7 
 

2005 ................ 98,649 26,179 22.8 0.6 46,116 42.4 0.7 62,283 60.4 0.8 53,040 49.4 0.7 
 

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. CO is carbon monoxide.
Series 2, Number 145 [ Page 11

Table 5. Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for PM2.5, by geographic

linkage method and survey year: United States, 1999–2005

Geographic linkage method

Number of 5-mile 10-mile 20-mile County

Survey survey

year respondents Number Percent SE Number Percent SE Number Percent SE Number Percent SE

1999 ................ 97,059 24,719 24.4 0.7 46,422 46.4 0.9 64,152 65.8 0.9 51,032 51.1 1.0

2000 ................ 100,618 39,621 36.3 0.8 64,383 61.1 0.9 81,201 79.6 0.9 73,311 69.8 1.0

2001 ................ 100,760 40,826 37.3 0.8 65,063 61.7 0.9 81,784 80.0 0.9 73,612 70.4 1.0

2002 ................ 93,386 38,806 38.5 0.8 61,695 63.2 0.9 76,916 81.0 0.9 70,005 71.9 1.0

2003 ................ 92,148 37,431 37.5 0.8 59,919 62.0 0.9 75,527 80.8 0.9 68,382 71.4 1.0

2004 ................ 94,460 37,315 36.8 0.8 60,572 61.7 0.9 77,144 80.9 0.8 69,907 71.4 1.0

2005 ................ 98,649 38,324 36.1 0.7 63,263 61.7 0.9 80,109 80.3 0.8 72,822 71.4 1.0

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. PM2.5 is particulate matter

less than 2.5 microns in diameter.

Table 6. Number, percentage, and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for O3, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

Number of 5-mile 10-mile 20-mile County

Survey survey

year respondents Number Percent SE Number Percent SE Number Percent SE Number Percent SE

1987 ................ 122,859 39,048 31.3 0.8 66,615 53.9 0.9 86,308 70.3 1.2 74,879 61.1 1.2

1988 ................ 122,310 37,244 29.9 0.8 65,615 53.5 1.0 85,507 70.3 1.2 75,358 61.8 1.3

1989 ................ 116,929 36,902 31.1 0.8 63,954 54.7 1.2 82,267 70.9 1.4 72,996 62.6 1.4

1990 ................ 119,631 38,592 32.0 0.8 66,391 55.7 1.2 85,104 72.0 1.2 74,047 62.6 1.4

1991 ................ 120,032 38,668 31.9 0.8 66,333 55.1 1.1 85,561 71.7 1.2 74,886 62.9 1.3

1992 ................ 120,700 37,241 30.3 0.8 65,660 54.1 1.2 85,675 71.3 1.4 74,309 61.8 1.4

1993 ................ 109,671 35,333 31.7 0.8 61,498 56.1 1.2 78,672 72.4 1.3 70,333 64.7 1.4

1994 ................ 116,179 37,241 31.6 0.8 64,626 55.5 1.2 82,852 71.7 1.4 74,976 64.8 1.4

1995 ................ 102,467 35,714 31.9 0.7 61,023 57.2 0.9 77,550 74.5 1.0 70,363 66.4 1.0

1996 ................ 63,402 21,226 30.0 0.9 36,561 54.9 1.2 47,906 74.5 1.3 43,330 65.9 1.3

1997 ................ 103,477 35,836 31.0 0.7 62,269 56.8 0.9 80,250 75.9 1.0 71,121 65.9 1.0

1998 ................ 98,785 34,085 30.8 0.7 59,521 56.9 0.9 76,502 75.7 1.0 67,725 65.6 1.0

1999 ................ 97,059 33,743 31.4 0.7 58,870 57.5 0.9 75,703 76.5 1.0 66,737 66.0 1.0

2000 ................ 100,618 35,996 31.8 0.7 62,771 58.9 0.8 80,325 78.3 0.9 70,321 67.2 1.0

2001 ................ 100,760 35,813 31.5 0.7 63,234 59.4 0.8 80,902 78.8 0.9 71,657 68.4 1.0

2002 ................ 93,386 32,755 31.3 0.7 58,768 59.6 0.8 75,170 78.7 0.9 67,034 69.0 0.9

2003 ................ 92,148 32,239 31.4 0.7 58,002 60.0 0.8 74,781 79.7 0.9 66,416 69.7 1.0

2004 ................ 94,460 32,937 31.5 0.7 59,937 60.5 0.8 77,347 81.0 0.8 68,867 70.8 1.0

2005 ................ 98,649 33,571 30.8 0.7 61,557 59.4 0.8 79,767 79.7 0.9 71,947 70.9 1.0

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. O3 is ozone.
Page 12 [ Series 2, Number 145

Table 7. Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for PM10, by geographic linkage

method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Number Percent SE Percent SE Percent SE

Total........................ 98,649 22.9 0.6 63.6 0.9 48.2 0.9

Poverty status

Below poverty threshold ........... 15,540 30.9 1.2 63.8 1.4 52.4 1.3

At or above poverty threshold ........ 83,109 21.7 0.6 63.6 0.9 47.6 0.9

Hispanic origin and race

Hispanic or Latino ............... 23,642 37.6 1.2 82.7 1.1 72.9 1.2

Mexican .................... 16,006 41.7 1.6 83.2 1.5 79.5 1.6

Not Hispanic or Latino............. 75,007 20.4 0.6 60.3 1.0 44.0 0.9

White only................... 56,483 17.6 0.7 56.2 1.1 40.0 1.0

Black or African American only ...... 13,216 31.4 1.2 75.1 1.7 57.5 1.5

Age

Less than 25 years .............. 37,137 24.2 0.7 64.4 0.9 49.6 0.9

25–64 years ................... 50,282 22.3 0.6 64.0 0.9 48.1 0.9

65 years and over ............... 11,230 21.6 0.9 59.4 1.3 45.0 1.2

Health status

Poor or fair ................... 9,658 24.1 0.9 59.7 1.3 46.6 1.3

Excellent, very good, or good ........ 88,701 22.8 0.6 64.0 0.9 48.4 0.9

Region

Northeast .................... 17,086 12.4 1.1 54.8 1.8 22.2 1.6

Midwest ..................... 21,678 20.3 1.4 54.1 1.7 41.0 1.7

South ....................... 35,291 18.8 0.9 60.3 1.8 44.5 1.5

West ....................... 24,594 41.7 1.8 87.4 1.6 85.2 1.9

2006 NCHS urban-rural classification

Large central metropolitan .......... 32,199 39.0 1.1 96.0 0.3 87.1 0.6

Large fringe metropolitan ........... 22,759 13.6 0.8 66.9 1.2 29.0 1.2

Medium metropolitan ............. 20,165 30.0 1.6 65.7 2.4 58.4 2.5

Small metropolitan ............... 8,868 13.2 3.3 29.6 4.7 22.2 5.1

Other counties ................. 14,658 5.1 1.4 17.7 2.8 10.9 2.8

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. PM10 is particulate matter

less than 10 microns in diameter. NCHS is the National Center for Health Statistics.
Series 2, Number 145 [ Page 13

Table 8. Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for SO2, by geographic linkage

method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Number Percent SE Percent SE Percent SE

Total........................ 98,649 17.1 0.5 57.7 0.9 44.6 0.9

Poverty status

Below poverty threshold ........... 15,540 23.6 1.0 56.0 1.4 45.9 1.4

At or above poverty threshold ........ 83,109 16.1 0.6 57.9 0.9 44.4 0.9

Hispanic origin and race

Hispanic or Latino ............... 23,642 24.0 1.1 65.1 1.3 60.2 1.3

Mexican .................... 16,006 19.4 1.1 57.4 1.7 56.5 1.7

Not Hispanic or Latino............. 75,007 15.9 0.6 56.4 1.0 42.0 0.9

White only................... 56,483 13.4 0.6 53.0 1.1 39.0 1.1

Black or African American only ...... 13,216 28.0 1.3 70.9 1.6 52.4 1.7

Age

Less than 25 years .............. 37,137 17.4 0.6 58.1 1.0 45.1 0.9

25–64 years ................... 50,282 16.9 0.6 58.1 0.9 44.5 0.9

65 years and over ............... 11,230 16.8 0.7 54.6 1.3 43.5 1.3

Health status

Poor or fair ................... 9,658 17.6 0.7 53.6 1.3 42.0 1.2

Excellent, very good, or good ........ 88,701 17.0 0.6 58.1 0.9 44.8 0.9

Region

Northeast .................... 17,086 33.0 1.5 82.0 1.6 60.4 2.1

Midwest ..................... 21,678 16.6 1.3 54.3 2.4 39.5 2.0

South ....................... 35,291 10.1 0.7 48.4 1.5 33.6 1.4

West ....................... 24,594 15.1 1.2 55.7 1.6 54.9 1.6

2006 NCHS urban-rural classification

Large central metropolitan .......... 32,199 31.0 1.2 87.3 0.6 84.7 0.8

Large fringe metropolitan ........... 22,759 15.6 0.9 73.3 1.1 37.9 1.2

Medium metropolitan ............. 20,165 16.1 1.4 50.2 2.7 38.6 2.4

Small metropolitan ............... 8,868 6.5 2.2 18.1 4.4 13.3 3.8

Other counties ................. 14,658 1.9 0.9 13.4 2.7 9.8 2.7

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. SO2 is sulfur dioxide.

NCHS is the National Center for Health Statistics.
Page 14 [ Series 2, Number 145

Table 9. Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for NO2, by geographic linkage

method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Number Percent SE Percent SE Percent SE

Total........................ 98,649 19.0 0.5 55.0 0.7 43.9 0.7

Poverty status

Below poverty threshold ........... 15,540 26.2 1.0 54.3 1.2 46.4 1.3

At or above poverty threshold ........ 83,109 17.9 0.5 55.1 0.7 43.5 0.7

Hispanic origin and race

Hispanic or Latino ............... 23,642 36.6 1.3 76.1 1.3 71.2 1.4

Mexican .................... 16,006 35.5 1.5 71.5 1.7 69.7 1.8

Not Hispanic or Latino............. 75,007 16.0 0.5 51.4 0.8 39.3 0.7

White only................... 56,483 13.0 0.5 47.1 0.9 35.1 0.8

Black or African American only ...... 13,216 27.3 1.2 66.7 1.6 53.0 1.6

Age

Less than 25 years .............. 37,137 19.7 0.6 56.0 0.8 45.0 0.8

25–64 years ................... 50,282 18.8 0.5 55.1 0.7 43.6 0.7

65 years and over ............... 11,230 17.7 0.7 51.4 1.1 41.8 1.1

Health status

Poor or fair ................... 9,658 19.1 0.7 49.7 1.1 40.8 1.1

Excellent, very good, or good....... 88,701 19.0 0.5 55.5 0.7 44.2 0.7

Region

Northeast .................... 17,086 30.0 1.4 74.8 1.4 54.0 1.7

Midwest ..................... 21,678 10.4 0.9 40.1 1.5 26.4 1.2

South ....................... 35,291 12.4 0.7 48.5 1.3 37.2 1.3

West ....................... 24,594 29.9 1.4 65.2 1.2 66.0 1.2

2006 NCHS urban-rural classification

Large central metropolitan .......... 32,199 38.8 1.1 90.3 0.6 86.1 0.7

Large fringe metropolitan ........... 22,759 16.1 0.9 71.7 1.2 39.0 1.2

Medium metropolitan ............. 20,165 16.3 1.4 44.4 2.5 39.3 2.3

Small metropolitan ............... 8,868 2.8 1.2 9.0 2.7 9.6 3.0

Other counties ................. 14,658 1.1 0.8 6.4 1.7 2.6 1.5

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. NO2 is nitrogen dioxide.

NCHS is the National Center for Health Statistics.
Series 2, Number 145 [ Page 15

Table 10. Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for CO, by geographic linkage

method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Number Percent SE Percent SE Percent SE

Total........................ 98,649 22.8 0.6 60.4 0.8 49.4 0.7

Poverty status

Below poverty threshold ........... 15,540 30.1 1.0 58.5 1.3 51.0 1.3

At or above poverty threshold ........ 83,109 21.7 0.6 60.7 0.8 49.2 0.7

Hispanic origin and race

Hispanic or Latino ............... 23,642 40.0 1.3 78.3 1.5 73.4 1.7

Mexican .................... 16,006 37.8 1.6 74.3 2.0 72.7 2.4

Not Hispanic or Latino............. 75,007 19.9 0.6 57.4 0.8 45.4 0.7

White only................... 56,483 16.4 0.6 53.4 0.9 41.1 0.8

Black or African American only ...... 13,216 33.4 1.4 70.1 1.6 58.6 1.4

Age

Less than 25 years .............. 37,137 23.3 0.6 61.4 0.8 50.5 0.8

25–64 years ................... 50,282 22.8 0.6 60.8 0.8 49.6 0.7

65 years and over ............... 11,230 20.9 0.8 55.8 1.1 45.3 1.0

Health status

Poor or fair ................... 9,658 23.5 0.8 53.9 1.1 44.9 1.0

Excellent, very good, or good ........ 88,701 22.7 0.6 61.1 0.8 49.9 0.7

Region

Northeast .................... 17,086 31.3 1.4 77.8 1.3 59.2 1.7

Midwest ..................... 21,678 16.5 1.1 49.8 1.7 37.4 1.5

South ....................... 35,291 12.7 0.7 46.2 1.3 33.4 1.0

West ....................... 24,594 39.2 1.7 80.8 1.7 81.0 1.5

2006 NCHS urban-rural classification

Large central metropolitan .......... 32,199 46.0 1.2 97.8 0.3 97.8 0.4

Large fringe metropolitan ........... 22,759 16.7 1.0 75.1 1.2 40.6 1.2

Medium metropolitan ............. 20,165 23.2 1.5 55.9 2.6 48.0 2.4

Small metropolitan ............... 8,868 4.5 2.1 11.5 3.5 7.9 3.1

Micropolitan ................... 14,658 1.1 0.7 5.4 1.4 3.3 1.3

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. CO is carbon monoxide.

NCHS is the National Center for Health Statistics.
Page 16 [ Series 2, Number 145

Table 11. Percentage and standard error (SE) of NHIS respondents linked to annual EPA air monitoring data for PM2.5, by geographic

linkage method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Number Percent SE Percent SE Percent SE

Total........................ 98,649 36.1 0.7 80.3 0.8 71.4 1.0

Poverty status

Below poverty threshold ........... 15,540 46.65 1.3 79.6 1.2 72.5 1.4

At or above poverty threshold ........ 83,109 34.53 0.7 80.4 0.9 71.2 1.0

Hispanic origin and race

Hispanic or Latino ............... 23,642 48.68 1.4 88.2 1.1 86.1 1.2

Mexican .................... 16,006 45.58 1.6 85.7 1.5 84.7 1.5

Not Hispanic or Latino............. 75,007 33.99 0.8 79.0 0.9 68.9 1.1

White only................... 56,483 29.92 0.8 76.3 1.1 65.1 1.2

Black or African American only ...... 13,216 51.99 1.6 89.4 1.2 82.8 1.5

Age

Less than 25 years .............. 37,137 37.79 0.8 81.3 0.9 72.7 1.0

25–64 years ................... 50,282 35.42 0.7 80.5 0.8 71.2 1.0

65 years and over ............... 11,230 34.09 1.0 76.6 1.2 67.7 1.3

Health status

Poor or fair ................... 9,658 37.22 1.1 76.7 1.1 67.7 1.4

Excellent, very good, or good ........ 88,701 36.00 0.7 80.7 0.9 71.7 1.0

Region

Northeast .................... 17,086 43.57 1.5 87.0 1.2 75.3 1.6

Midwest ..................... 21,678 35.38 1.5 73.1 2.2 64.0 2.3

South ....................... 35,291 29.42 1.4 77.8 1.5 65.1 1.9

West ....................... 24,594 41.56 1.5 86.7 1.4 86.6 1.1

2006 NCHS urban-rural classification

Large central metropolitan .......... 32,199 55.66 1.1 97.6 0.3 99.7 0.1

Large fringe metropolitan ........... 22,759 29.75 1.3 89.8 0.8 70.2 1.4

Medium metropolitan ............. 20,165 40.77 1.8 89.7 1.3 80.5 2.3

Small metropolitan ............... 8,868 28.95 3.7 59.1 5.8 47.8 5.8

Other counties ................. 14,658 9.03 2.0 34.1 3.4 24.1 3.7

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. PM2.5 is particulate matter

less than 2.5 microns in diameter. NCHS is the National Center for Health Statistics.
Series 2, Number 145 [ Page 17

Table 12. Percentage and standard error (SE) of NHIS respondents linked to annual EPA monitoring data for O3, by geographic linkage

method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Number Percent SE Percent SE Percent SE

Total........................ 98,649 30.8 0.7 79.7 0.9 70.9 1.0

Poverty status

Below poverty threshold ........... 15,540 37.0 1.2 77.6 1.3 67.7 1.4

At or above poverty threshold ........ 83,109 29.9 0.7 80.1 0.9 71.3 1.0

Hispanic origin and race

Hispanic or Latino ............... 23,642 46.2 1.3 88.9 1.2 84.3 1.3

Mexican .................... 16,006 48.6 1.6 86.1 1.6 84.2 1.5

Not Hispanic or Latino............. 75,007 28.2 0.7 78.2 1.0 68.6 1.1

White only................... 56,483 25.4 0.7 76.0 1.1 66.9 1.2

Black or African American only ...... 13,216 38.7 1.3 87.0 1.5 72.7 1.6

Age

Less than 25 years .............. 37,137 31.6 0.7 80.4 1.0 71.7 1.0

25–64 years ................... 50,282 30.6 0.7 80.1 0.9 71.0 1.0

65 years and over ............... 11,230 29.6 1.0 76.3 1.1 67.6 1.3

Health status

Poor or fair ................... 9,658 30.5 0.9 74.8 1.2 64.8 1.3

Excellent, very good, or good ........ 88,701 30.8 0.7 80.2 0.9 71.5 1.0

Region

Northeast .................... 17,086 30.9 1.5 91.3 1.3 76.2 1.9

Midwest ..................... 21,678 28.8 1.3 76.3 2.1 65.0 2.3

South ....................... 35,291 23.5 1.0 74.9 1.6 63.0 1.9

West ....................... 24,594 45.0 1.7 81.6 1.6 85.9 1.4

2006 NCHS urban-rural classification

Large central metropolitan .......... 32,199 49.6 1.2 97.5 0.3 90.4 0.7

Large fringe metropolitan ........... 22,759 27.4 1.1 94.0 0.6 79.9 1.2

Medium metropolitan ............. 20,165 36.1 1.8 89.9 1.5 84.8 2.3

Small metropolitan ............... 8,868 15.3 2.8 46.1 4.9 42.4 5.3

Other counties ................. 14,658 4.7 1.2 31.8 3.6 19.8 3.6

NOTES: Percentages and standard errors calculated using survey weights. NHIS is the National Health Interview Survey. EPA is the U.S. Environmental Protection Agency. O3 is ozone. NCHS is the

National Center for Health Statistics.
Page 18 [ Series 2, Number 145

Table 13. Median and interquartile range of PM10 exposure (μg/m3

) for respondents linked to annual EPA monitoring data, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

5-mile 10-mile 20-mile County

Survey year Median 25th 75th Median 25th 75th Median 25th 75th Median 25th 75th

1987 ................ 37.7 32.0 46.7 38.2 32.9 46.2 37.2 32.3 44.7 37.5 31.1 45.3
 

1988 ................ 35.9 30.8 40.6 35.6 30.7 41.3 35.9 31.3 40.6 36.3 29.7 41.2
 

1989 ................ 33.5 28.7 38.7 34.1 29.0 39.4 34.2 28.7 38.3 33.4 28.6 40.4
 

1990 ................ 30.6 25.9 35.1 30.7 26.1 35.3 30.5 26.3 34.8 30.9 25.7 36.4
 

1991 ................ 30.5 25.9 35.6 30.9 26.1 35.2 31.0 26.0 33.9 30.3 25.5 35.5
 

1992 ................ 27.6 23.4 31.6 28.1 24.0 31.6 27.3 23.6 30.7 27.2 23.0 32.0
 

1993 ................ 26.9 23.1 31.1 27.1 23.0 31.3 27.0 23.1 30.4 26.7 22.8 32.6
 

1994 ................ 27.1 22.7 32.7 27.3 22.9 32.7 27.4 22.7 32.0 26.5 21.9 33.8
 

1995 ................ 25.1 21.5 31.1 25.5 21.5 30.5 26.0 21.3 30.2 25.1 21.2 31.4
 

1996 ................ 24.6 20.8 30.0 24.7 20.8 30.1 24.5 20.8 29.4 24.3 20.4 30.1
 

1997 ................ 24.6 21.3 29.6 24.6 21.3 29.7 24.6 21.1 28.7 24.4 21.1 29.0
 

1998 ................ 25.3 22.2 29.6 25.6 22.2 29.6 25.8 22.4 28.5 25.1 21.3 29.8
 

1999 ................ 25.3 21.7 30.1 25.1 21.7 29.3 24.9 21.5 28.7 25.1 21.5 30.3
 

2000 ................ 24.9 21.4 29.6 25.1 21.7 29.6 25.1 21.6 28.6 24.7 21.0 29.6
 

2001 ................ 24.2 20.8 29.3 24.5 21.0 28.7 24.1 21.1 28.0 24.2 20.5 28.6
 

2002 ................ 23.8 20.2 29.1 23.6 20.4 28.3 23.2 20.4 26.9 23.4 19.9 28.8
 

2003 ................ 23.9 20.6 29.4 23.9 20.5 29.2 23.8 20.5 27.9 23.9 20.3 28.4
 

2004 ................ 22.5 19.4 26.7 22.6 19.5 27.3 22.3 19.5 25.7 22.7 19.5 27.0
 

2005 ................ 24.5 21.3 29.0 24.8 21.3 29.5 24.8 21.3 29.2 24.5 20.7 28.3
 

NOTES: Percentiles calculated using survey weights. PM10 is particulate matter less than 10 microns in diameter. EPA is the U.S. Environmental Protection Agency.

Table 14. Median and interquartile range of SO2 exposure (ppb) for respondents linked to annual EPA monitoring data, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

5-mile 10-mile 20-mile County

Survey year Median 25th 75th Median 25th 75th Median 25th 75th Median 25th 75th

1987 ................ 8.2 4.6 12.0 7.9 4.5 11.4 7.7 4.4 11.2 7.4 4.1 11.1
 

1988 ................ 8.1 4.6 12.2 7.7 4.4 11.4 7.4 4.4 11.2 7.2 4.3 10.3
 

1989 ................ 8.1 4.6 12.2 7.7 4.5 11.4 7.4 4.1 10.8 7.1 3.6 10.8
 

1990 ................ 7.6 4.0 10.9 7.4 4.0 10.4 7.0 3.7 9.8 6.5 3.3 9.7
 

1991 ................ 7.8 4.4 11.2 7.5 4.2 10.1 7.1 3.3 9.5 7.0 3.3 9.5
 

1992 ................ 7.0 3.9 9.6 6.6 4.1 9.2 6.5 3.4 9.0 6.1 3.4 8.7
 

1993 ................ 6.6 3.8 9.0 6.3 3.6 8.9 6.2 3.3 8.6 6.1 2.7 8.2
 

1994 ................ 6.5 3.9 9.1 6.2 3.8 8.6 6.0 3.5 8.4 5.9 3.0 7.9
 

1995 ................ 5.5 3.6 7.1 5.0 3.2 6.8 4.8 3.0 6.7 4.6 3.0 6.2
 

1996 ................ 5.4 3.4 7.3 5.1 3.2 7.1 4.8 2.9 6.9 4.8 2.5 6.5
 

1997 ................ 5.5 3.7 7.4 5.3 3.2 7.0 5.1 2.9 6.8 4.7 2.5 6.4
 

1998 ................ 5.4 3.3 7.2 5.1 3.0 6.8 4.8 2.8 6.7 4.4 2.6 6.4
 

1999 ................ 5.2 3.4 7.1 4.8 3.1 6.6 4.6 2.8 6.5 4.2 2.6 6.5
 

2000 ................ 4.9 2.8 6.5 4.6 2.6 6.3 4.3 2.4 6.1 3.9 2.3 6.0
 

2001 ................ 4.7 2.9 6.3 4.4 2.7 6.1 4.3 2.6 5.7 3.7 2.3 5.3
 

2002 ................ 4.2 2.6 5.7 4.0 2.3 5.5 4.0 2.2 5.3 3.6 2.2 4.9
 

2003 ................ 4.2 2.5 5.7 4.0 2.4 5.5 3.8 2.1 5.5 3.4 2.0 4.9
 

2004 ................ 4.4 2.8 5.6 4.0 2.6 5.3 3.8 2.5 5.1 3.5 2.4 4.8
 

2005 ................ 4.3 2.7 5.7 4.1 2.3 5.4 3.8 2.3 5.2 3.6 2.2 5.0
 

NOTES: Percentiles calculated using survey weights. SO2 is sulfur dioxide. EPA is the U.S. Environmental Protection Agency.
Series 2, Number 145 [ Page 19

Table 15. Median and interquartile range of NO2 exposure (ppb) for respondents linked to annual EPA monitoring data, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

5-mile 10-mile 20-mile County

Survey year Median 25th 75th Median 25th 75th Median 25th 75th Median 25th 75th

1987 ................ 27.8 22.5 37.2 27.2 21.9 34.2 25.3 20.5 31.5 25.1 19.8 32.1
 

1988 ................ 27.1 22.5 35.5 26.4 21.3 33.1 25.1 20.3 31.3 24.7 19.8 30.3
 

1989 ................ 27.2 22.0 35.1 25.8 21.2 31.7 24.8 19.9 30.0 25.1 18.6 29.2
 

1990 ................ 25.5 20.2 33.6 24.6 19.2 30.0 22.9 18.1 28.1 22.6 17.9 27.8
 

1991 ................ 25.1 19.8 32.4 24.2 18.9 29.4 22.6 17.5 27.4 21.5 16.5 27.9
 

1992 ................ 24.4 20.1 29.6 23.5 18.6 28.3 21.9 17.8 26.6 22.3 16.4 26.4
 

1993 ................ 23.9 19.1 29.9 23.5 18.4 28.1 21.8 17.1 26.9 21.1 16.8 26.7
 

1994 ................ 24.8 20.3 31.8 23.8 19.1 29.9 22.4 17.5 27.9 22.4 16.6 28.6
 

1995 ................ 23.1 18.7 29.8 22.3 17.3 28.6 20.9 16.4 27.1 21.1 15.8 27.1
 

1996 ................ 22.5 18.1 29.3 21.9 17.7 28.6 20.4 16.3 26.7 20.5 16.3 26.7
 

1997 ................ 21.9 17.0 28.2 20.3 16.0 27.9 19.3 15.1 25.7 19.2 14.3 25.7
 

1998 ................ 22.8 17.7 29.3 21.4 16.5 27.1 19.8 15.8 25.0 18.7 14.6 25.2
 

1999 ................ 22.4 17.5 28.0 20.8 16.6 26.4 18.9 15.4 24.6 18.7 14.9 25.4
 

2000 ................ 21.3 16.6 27.1 19.6 15.4 25.1 18.4 14.6 24.0 18.0 13.3 24.0
 

2001 ................ 21.0 16.6 27.4 19.6 15.7 25.8 18.5 14.6 24.0 18.0 13.2 24.1
 

2002 ................ 19.7 15.9 25.5 18.7 14.6 24.8 17.5 13.7 23.5 17.3 12.8 22.4
 

2003 ................ 18.6 14.4 24.8 17.7 14.2 23.8 16.9 12.8 22.0 16.3 12.1 21.9
 

2004 ................ 17.4 13.9 23.2 16.6 13.0 22.2 15.7 12.4 20.8 15.3 12.0 20.4
 

2005 ................ 17.5 13.5 23.4 16.7 13.0 21.7 15.8 12.0 20.1 15.1 11.7 20.0
 

NOTES: Percentiles calculated using survey weights. NO2 is nitrogen dioxide. EPA is the U.S. Environmental Protection Agency.

Table 16. Median and interquartile range of CO exposure (ppm) for respondents linked to annual EPA monitoring data, by geographic

linkage method and survey year: United States, 1987–2005

Geographic linkage method

5-mile 10-mile 20-mile County

Survey year Median 25th 75th Median 25th 75th Median 25th 75th Median 25th 75th

1987 ..................... 1.28 0.96 1.75 1.27 0.97 1.73 1.24 0.97 1.70 1.21 0.96 1.68
 

1988 ..................... 1.23 0.92 1.64 1.22 0.94 1.62 1.18 0.93 1.61 1.19 0.90 1.58
 

1989 ..................... 1.29 0.94 1.77 1.26 0.93 1.72 1.21 0.93 1.66 1.24 0.90 1.63
 

1990 ..................... 1.18 0.92 1.58 1.17 0.89 1.50 1.13 0.90 1.44 1.08 0.88 1.41
 

1991 ..................... 1.14 0.85 1.57 1.12 0.83 1.49 1.08 0.84 1.45 1.08 0.80 1.39
 

1992 ..................... 1.07 0.84 1.46 1.06 0.84 1.38 1.03 0.84 1.34 0.99 0.82 1.33
 

1993 ..................... 1.03 0.78 1.39 1.03 0.78 1.29 0.95 0.80 1.29 0.99 0.78 1.27
 

1994 ..................... 0.99 0.80 1.31 1.00 0.80 1.31 0.98 0.80 1.28 0.96 0.78 1.28
 

1995 ..................... 0.90 0.73 1.18 0.90 0.74 1.17 0.88 0.75 1.13 0.87 0.72 1.14
 

1996 ..................... 0.86 0.69 1.17 0.84 0.68 1.14 0.86 0.70 1.12 0.83 0.67 1.10
 

1997 ..................... 0.78 0.61 1.05 0.79 0.61 1.03 0.77 0.62 1.00 0.75 0.60 0.98
 

1998 ..................... 0.81 0.61 1.06 0.80 0.62 1.01 0.80 0.61 0.98 0.80 0.57 0.97
 

1999 ..................... 0.79 0.63 1.06 0.78 0.63 1.05 0.76 0.63 1.03 0.75 0.60 1.04
 

2000 ..................... 0.70 0.53 0.92 0.69 0.53 0.92 0.68 0.53 0.93 0.66 0.49 0.89
 

2001 ..................... 0.68 0.50 0.88 0.66 0.50 0.87 0.64 0.50 0.87 0.62 0.48 0.84
 

2002 ..................... 0.60 0.46 0.81 0.59 0.45 0.79 0.59 0.45 0.78 0.57 0.45 0.80
 

2003 ..................... 0.61 0.48 0.83 0.60 0.47 0.79 0.58 0.46 0.78 0.58 0.45 0.77
 

2004 ..................... 0.55 0.43 0.72 0.54 0.42 0.72 0.52 0.42 0.72 0.53 0.41 0.68
 

2005 ..................... 0.50 0.41 0.65 0.50 0.40 0.64 0.50 0.39 0.63 0.50 0.39 0.60
 

NOTES: Percentiles calculated using survey weights. CO is carbon monoxide. EPA is the U.S. Environmental Protection Agency.
Page 20 [ Series 2, Number 145

Table 17. Median and interquartile range of PM2.5 exposure (μg/m3

) for respondents linked to annual EPA monitoring data, by geographic

linkage method and survey year: United States, 1999–2005

Geographic linkage method

5-mile 10-mile 20-mile County

Survey year Median 25th 75th Median 25th 75th Median 25th 75th Median 25th 75th

1999 ..................... 14.4 11.9 16.9 14.5 11.8 16.8 14.3 11.9 16.6 14.2 11.6 17.1 
 

2000 ..................... 13.8 11.5 16.0 13.7 11.4 15.9 13.7 11.4 16.0 13.4 11.4 16.0 
 

2001 ..................... 13.5 11.2 15.6 13.3 11.1 15.5 13.3 11.1 15.3 13.0 10.7 15.7 
 

2002 ..................... 13.4 11.0 15.2 13.1 10.7 15.0 13.0 10.7 14.8 12.8 10.7 14.8 
 

2003 ..................... 12.9 10.8 14.8 12.7 10.7 14.6 12.7 10.5 14.6 12.5 10.4 14.6 
 

2004 ..................... 12.6 10.4 14.2 12.4 10.3 14.1 12.2 10.2 13.9 12.1 10.1 14.0 
 

2005 ..................... 13.6 10.9 15.5 13.4 10.8 15.5 13.4 10.6 15.5 13.2 10.6 15.4 
 

NOTES: Percentiles calculated using survey weights. PM2.5 is particulate matter less than 2.5 microns in diameter. EPA is the U.S. Environmental Protection Agency.

Table 18. Median and interquartile range of PM10 exposure (μg/m3) for respondents linked to annual EPA monitoring data, by geographic

linkage method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Median 25th 75th Median 25th 75th Median 25th 75th

Total........................ 24.5 21.3 29.0 24.8 21.3 29.2 24.5 20.7 28.3 
 

Poverty status

Below poverty threshold ........... 25.4 21.7 29.6 26.2 22.4 29.6 25.1 22.5 30.0 
 

At or above poverty threshold ........ 24.4 21.2 28.8 24.6 21.0 28.8 24.4 20.7 28.3 
 

Hispanic origin and race

Hispanic or Latino ............... 26.7 21.5 30.9 26.9 21.7 30.5 26.3 22.7 30.3 
 

Mexican .................... 27.7 22.0 33.2 27.5 22.8 32.0 28.1 23.1 30.3 
 

Not Hispanic or Latino............. 24.4 21.2 28.2 24.4 21.2 28.3 23.9 20.6 28.3 
 

White only................... 24.0 21.2 27.5 24.2 21.1 27.9 23.7 20.6 28.1 
 

Black or African American only ...... 25.1 21.6 29.6 26.2 22.5 29.6 25.1 22.5 28.3

Age

Less than 25 years .............. 24.7 21.3 29.5 24.8 21.5 29.4 24.5 21.0 28.5 
 

25–64 years ................... 24.5 21.3 28.9 24.7 21.3 29.0 24.5 20.7 28.3 
 

65 years and over ............... 24.5 21.2 28.3 24.5 20.8 28.8 24.5 20.4 28.3 
 

Health status

Poor or fair ................... 25.1 21.5 29.2 25.0 21.7 29.6 24.7 21.1 29.2 
 

Excellent, very good, or good ........ 24.5 21.3 29.0 24.7 21.3 29.0 24.5 20.7 28.3 
 

Region

Northeast .................... 24.5 22.7 29.1 27.3 22.7 29.6 24.3 20.2 27.7 
 

Midwest ..................... 25.6 22.5 28.9 26.4 23.6 29.3 27.0 23.3 28.3 
 

South ....................... 22.7 19.2 26.3 23.6 19.9 26.3 23.6 20.4 25.5 
 

West ....................... 25.5 21.4 30.9 25.6 20.7 31.9 25.0 20.6 30.3 
 

2006 NCHS urban-rural classification

Large central metropolitan .......... 26.3 22.3 29.6 27.4 23.3 29.9 26.1 23.6 30.3 
 

Large fringe metropolitan ........... 23.6 19.3 28.9 24.8 21.6 28.6 23.5 19.5 27.4 
 

Medium metropolitan ............. 24.2 20.4 27.7 23.0 19.6 25.9 23.0 19.6 25.8 
 

Small metropolitan ............... 22.2 20.7 24.8 22.2 20.2 24.3 22.2 14.8 24.5 
 

Other counties ................. 22.2 19.4 24.9 22.2 19.4 24.9 22.0 19.4 24.9 
 

NOTES: Percentiles calculated using survey weights. PM10 is particulate matter less than 10 microns in diameter. EPA is the U.S. Environmental Protection Agency. NCHS is the National Center for

Health Statistics.
Series 2, Number 145 [ Page 21

Table 19. Median and interquartile range of SO2 exposure (ppb) for respondents linked to annual EPA monitoring data, by geographic

linkage method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Median 25th 75th Median 25th 75th Median 25th 75th

Total........................ 4.3 2.7 5.7 3.8 2.3 5.2 3.6 2.2 5.0

Poverty status

Below poverty threshold ........... 4.4 2.9 5.7 3.9 2.3 5.3 3.5 2.3 5.0

At or above poverty threshold ........ 4.3 2.7 5.7 3.8 2.3 5.2 3.6 2.2 5.0

Hispanic origin and race

Hispanic or Latino ............... 4.0 2.2 5.9 3.0 1.8 4.3 3.0 1.6 3.8

Mexican .................... 2.5 2.1 4.5 2.9 2.0 3.5 3.0 1.7 3.5

Not Hispanic or Latino............. 4.4 3.0 5.7 4.1 2.4 5.3 3.8 2.4 5.1

White only................... 4.6 3.1 5.8 4.1 2.4 5.3 3.9 2.5 5.2

Black or African American only ...... 4.4 3.1 5.1 4.1 2.9 5.4 3.8 2.4 4.9

Age

Less than 25 years .............. 4.3 2.7 5.6 3.8 2.3 5.2 3.6 2.2 5.0

25–64 years ................... 4.3 2.7 5.7 3.7 2.3 5.2 3.6 2.2 5.0

65 years and over ............... 4.5 2.9 5.9 4.1 2.4 5.4 3.8 2.3 5.1

Health status

Poor or fair ................... 4.4 2.5 5.7 3.7 2.2 5.2 3.6 2.2 4.9

Excellent, very good, or good ........ 4.3 2.7 5.7 3.8 2.3 5.2 3.6 2.2 5.0

Region

Northeast .................... 5.9 4.6 7.6 5.4 4.4 7.6 5.2 4.3 6.5

Midwest ..................... 4.1 3.1 5.1 4.1 3.1 4.8 3.8 3.1 5.0

South ....................... 3.4 1.9 4.9 3.1 1.8 5.0 3.1 1.6 4.4

West ....................... 2.2 1.7 2.8 2.2 1.7 3.0 2.6 1.7 3.3

2006 NCHS urban-rural classification

Large central metropolitan .......... 4.2 2.5 5.7 3.5 2.1 4.7 3.4 2.5 4.5

Large fringe metropolitan ........... 4.3 3.2 5.5 4.3 2.9 5.4 4.3 1.8 5.4

Medium metropolitan ............. 4.6 2.6 5.9 4.1 2.3 5.3 4.3 1.7 5.2

Small metropolitan ............... 4.6 3.3 7.3 4.1 3.3 6.2 4.6 3.3 7.3

Other counties ................. † † † 3.5 2.2 5.1 3.8 2.4 7.4

† Estimates for groups with fewer than 100 respondents or fewer than 25 respondents above the 75th percentile or below the 25th percentile are not shown.

NOTES: Percentiles calculated using survey weights. SO2 is sulfur dioxide. EPA is the U.S. Environmental Protection Agency. NCHS is the National Center for Health Statistics.
Page 22 [ Series 2, Number 145

Table 20. Median and interquartile range of NO2 exposure (ppb) for respondents linked to annual EPA monitoring data, by geographic

linkage method and respondent characteristic: United States, 2005

Geographic linkage method

5-mile 20-mile County

Characteristic Median 25th 75th Median 25th 75th Median 25th 75th

Total........................ 17.5 13.5 23.4 15.8 12.0 20.1 15.1 11.7 20.0

Poverty status

Below poverty threshold ........... 18.5 15.0 24.4 15.9 12.3 22.3 15.9 12.1 22.0

At or above poverty threshold ........ 17.3 13.4 22.8 15.7 12.0 20.1 15.1 11.7 19.8

Hispanic origin and race

Hispanic or Latino ............... 19.9 14.9 27.4 16.5 12.3 23.9 15.8 11.7 23.0

Mexican .................... 19.2 14.9 25.9 16.5 13.0 23.9 16.5 12.8 23.0

Not Hispanic or Latino............. 17.3 13.3 21.6 15.5 12.0 19.6 15.1 11.7 19.2

White only................... 16.4 12.6 20.0 15.3 11.9 19.2 15.0 11.4 18.6

Black or African American only ...... 19.2 15.4 21.7 16.6 12.6 20.0 16.0 12.2 21.7

Age

Less than 25 years .............. 17.7 13.6 23.2 15.7 12.2 20.2 15.1 11.7 20.0

25–64 years ................... 17.7 13.6 24.0 15.7 12.1 20.2 15.3 11.7 20.1

65 years and over ............... 17.3 13.3 22.2 15.8 11.9 20.0 15.4 11.1 19.6

Health status

Poor or fair ................... 17.7 14.1 24.1 15.3 11.6 20.2 15.4 11.4 20.0

Excellent, very good, or good ........ 17.6 13.5 23.4 15.8 12.1 20.1 15.1 11.7 20.0

Region

Northeast .................... 20.0 16.1 26.3 17.5 15.3 26.0 16.6 13.8 22.1

Midwest ..................... 17.8 15.1 20.5 17.0 12.8 19.6 18.3 13.0 23.9

South ....................... 14.1 10.1 17.7 12.0 9.1 14.5 12.0 8.6 14.5

West ....................... 18.5 14.5 24.5 17.4 13.6 23.8 18.5 14.1 22.3

2006 NCHS urban-rural classification

Large central metropolitan .......... 20.0 16.4 26.3 17.4 13.3 23.8 18.1 14.5 23.0

Large fringe metropolitan ........... 16.9 12.1 20.4 17.0 12.6 20.0 13.3 9.1 17.7

Medium metropolitan ............. 14.3 11.1 16.1 12.6 10.6 15.1 13.7 11.1 15.1

Small metropolitan ............... † † † 8.4 7.9 12.3 8.4 7.9 10.6

Other counties ................. † † † 9.6 6.8 12.8 † † †

† Estimates for groups with fewer than 100 respondents or fewer than 25 respondents above the 75th percentile or below the 25th percentile are not shown.
 

NOTES: Percentiles calculated using survey weights. NO2 is nitrogen dioxide. EPA is the U.S. Environmental Protection Agency. NCHS is the National Center for Health Statistics.
 
Series 2, Number 145 [ Page 23

Table 21. Median and interquartile range of CO

linkage method and respondent characteristic:

exposure (ppm) for

United States, 2005

respondents linked to annual EPA monitoring data, by geographic

Geographic linkage method

5-mile 20-mile County

Characteristic Median 25th 75th Median 25th 75th Median 25th 75th

Total. . . . . . . . . . . . . . . . . . . . . . . .

Poverty status

Below poverty threshold ...........

At or above poverty threshold ........

Hispanic origin and race

Hispanic or Latino ...............

Mexican ....................

Not Hispanic or Latino.............

White only. . . . . . . . . . . . . . . . . . .

Black or African American only ......

Age

Less than 25 years ..............

25–64 years ...................

65 years and over ...............

Health status

Poor or fair ...................

Excellent, very good, or good ........

Region

Northeast ....................

Midwest .....................

South .......................

West .......................

2006 NCHS urban-rural classification

Large central metropolitan ..........

Large fringe metropolitan ...........

Medium metropolitan .............

Small metropolitan ...............

Other counties .................

0.50

0.50

0.50

0.55

0.55

0.49

0.49

0.49

0.50

0.50

0.51

0.50

0.50

0.52

0.45

0.47

0.60

0.55

0.48

0.44

†

†

0.41

0.40

0.41

0.42

0.42

0.40

0.39

0.41

0.41

0.41

0.41

0.41

0.41

0.38

0.38

0.41

0.43

0.43

0.38

0.39

†

†

0.65

0.65

0.65

0.70

0.71

0.63

0.62

0.65

0.65

0.65

0.65

0.64

0.65

0.62

0.55

0.56

0.74

0.71

0.60

0.59

†

†

0.50

0.49

0.50

0.54

0.54

0.49

0.48

0.50

0.50

0.50

0.50

0.49

0.50

0.48

0.45

0.47

0.61

0.54

0.50

0.45

0.45

0.37

0.39

0.39

0.39

0.44

0.40

0.38

0.38

0.40

0.39

0.39

0.39

0.39

0.39

0.36

0.37

0.38

0.47

0.40

0.40

0.38

0.38

0.33

0.63

0.64

0.63

0.66

0.65

0.61

0.60

0.59

0.63

0.63

0.64

0.64

0.63

0.69

0.54

0.56

0.79

0.68

0.57

0.55

0.81

0.44

0.50

0.50

0.49

0.51

0.49

0.49

0.48

0.50

0.49

0.50

0.49

0.49

0.50

0.49

0.48

0.47

0.60

0.53

0.46

0.45

†

†

0.39

0.39

0.39

0.45

0.42

0.38

0.38

0.38

0.38

0.39

0.39

0.38

0.39

0.33

0.37

0.38

0.46

0.41

0.32

0.39

†

†

0.60

0.60

0.60

0.60

0.60

0.60

0.60

0.59

0.60

0.60

0.60

0.60

0.60

0.57

0.54

0.53

0.79

0.61

0.55

0.52

†

†

† Estimates for groups with fewer than 100 respondents or fewer than 25 respondents above the 75th percentile or below the 25th percentile are not shown.
 

NOTES: Percentiles calculated using survey weights. CO is carbon monoxide. EPA is the U.S. Environmental Protection Agency. NCHS is the National Center for Health Statistics.
 
Page 24 [ Series 2, Number 145

Table 22. Median and interquartile range of PM2.5 (μg/m3

) exposure among respondents

geographic linkage method and respondent characteristic: United States, 2005

linked to annual EPA air monitoring data, by

Characteristic

Geographic linkage method

5-mile 20-mile County

Median 25th 75th Median 25th 75th Median 25th 75th

Total. . . . . . . . . . . . . . . . . . . . . . . .

Poverty status

Below poverty threshold ...........

At or above poverty threshold ........

Hispanic origin and race

Hispanic or Latino ...............

Mexican ....................

Not Hispanic or Latino.............

White only. . . . . . . . . . . . . . . . . . .

Black or African American only ......

Age

Less than 25 years ..............

25–64 years ...................

65 years and over ...............

Health status

Poor or fair ...................

Excellent, very good, or good ........

Region

Northeast ....................

Midwest .....................

South .......................

West .......................

2006 NCHS urban-rural classification

Large central metropolitan ..........

Large fringe metropolitan ...........

Medium metropolitan .............

Small metropolitan ...............

Other counties .................

13.6

13.9

13.5

13.5

13.2

13.6

13.3

14.4

13.5

13.6

13.5

13.7

13.5

13.6

15.5

13.6

10.3

14.4

13.5

12.8

11.7

12.4

10.9

11.3

10.7

10.5

10.5

11

10.6

12.8

10.9

10.9

10.7

11.4

10.8

12.4

12.9

11.7

8.6

11.8

11.6

10.3

8.2

10.1

15.5

15.8

15.5

15.6

16

15.5

15.4

15.8

15.5

15.5

15.6

15.7

15.5

14.9

16.4

15.1

14.7

16.0

15.5

15.0

13.9

14.6

13.4

13.7

13.4

12.6

12.3

13.5

13.4

14.2

13.4

13.4

13.4

13.5

13.4

13.6

15.6

13.5

9.9

13.7

13.9

13.0

12.7

13.6

10.6

10.8

10.6

10.1

10.1

10.8

10.6

12.5

10.6

10.6

10.6

10.9

10.6

11.7

12.9

11.7

9.0

10.6

10.8

10.4

9.6

10.8

15.5

15.7

15.4

15.7

16.1

15.5

15.4

15.8

15.5

15.5

15.4

15.6

15.5

14.7

16.3

15.0

14.0

16.1

15.5

14.8

14.1

14.9

13.2

13.5

13.2

12.6

12.5

13.3

13.2

14.2

13.2

13.2

13.1

13.3

13.2

13.6

15.3

13.2

10.5

13.3

13.6

12.6

12.1

12.9

10.6

11.1

10.6

10.5

10.5

10.8

10.6

12.5

10.6

10.6

10.6

11.0

10.6

11.7

12.9

11.2

9.0

11.0

11.0

10.3

8.1

10.2

15.4

15.4

15.4

15.4

15.4

15.4

15.3

15.7

15.4

15.4

15.4

15.4

15.4

14.4

16.2

14.8

14.1

15.6

15.1

14.7

14.1

14.6

NOTES: Percentiles

Health Statistics.

calculated using survey weights. PM2.5 is particulate matter less than 2.5 microns in diameter. EPA is the U.S. Environmental Protection Agency. NCHS is the Natinal Center for
Vital and Health Statistics

series descriptions

SERIES 1.	 Programs and Collection Procedures—These reports

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SERIES 2.	 Data Evaluation and Methods Research—These reports

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Data from direct examination, testing, and measurement on

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SERIES 12.	 Data From the Institutionalized Population Surveys—

Discontinued in 1975. Reports from these surveys are

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reports contain statistics on health resources and the public’s

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DHHS Publication No. (PHS) 2008-1345, Series 2, No. 145