Final Report: Development of Exposure and Health Outcome Indicators for Those with Asthma or Other Respiratory Problems

EPA Grant Number: R833629
Title: Development of Exposure and Health Outcome Indicators for Those with Asthma or Other Respiratory Problems
Investigators: Meng, Ying-Ying , Jerrett, Michael , Ritz, Beate R. , Wilhelm, Michelle
Institution: University of California - Los Angeles
EPA Project Officer: Nolt-Helms, Cynthia
Project Period: September 1, 2007 through August 31, 2010 (Extended to February 29, 2012)
Project Amount: $500,000
RFA: Development of Environmental Health Outcome Indicators (2006) RFA Text |  Recipients Lists
Research Category: Health Effects , Health

Objective:

Asthma is the most common chronic lung disease in the United States. In 2010, approximately 39 million Americans (13%) reported being diagnosed with asthma.[1] In 2009, 5 million (14%) Californians reported being diagnosed with asthma.[2] Air pollutants, particularly traffic emissions, affect asthma sufferers through airway inflammation and may affect symptom severity as a function of acute and chronic airway obstruction.[3] Currently, the EPA outcome-based environmental health indicators available for asthma are limited with only prevalence of lifetime asthma diagnosis, current asthma, and asthma attack.[4] More and better asthma-related health outcome indicators are needed to evaluate environmental strategies that will improve the health of asthmatics and individuals suffering from other respiratory problems. The National Health Interview Survey (NHIS) has collected information on asthma-related emergency department (ED) visits, doctor’s visits, and absences from school/work. These indicators are important for assessing the benefits and costs associated with further incremental reductions in air pollutant concentrations and exposures because they affect the lives of the majority of asthma sufferers. Little has been done to explore whether these data can be used as asthma health outcome indicators. The availability of the results of several California Health Interview Surveys (CHIS) makes it possible for the first time to relate data on air pollutant and traffic exposure with health data for a large number of asthma sufferers at multiple time points due to its large sample size and collection of geocodable residential address information, as well as information on duration of residence in the same neighborhood.

The goal of this research was to investigate the feasibility of combining existing monitoring and CHIS data to develop health outcome indicators, such as asthma attacks, asthma-related ED visits, absences from school/work, asthma medication use, and frequency of asthma symptoms for those with asthma, as well as asthma-like symptoms, seeking medical help for breathing problems and absences from work/school due to breathing problems for those without asthma diagnoses. The project objectives were to:

1) Develop long-term (12-, 24- and 36-month) criteria air pollutant exposure indicators for CHIS 2003 and CHIS 2005 respondents using existing measurement data for O3, NO2, PM10, and PM2. 5 from the California Air Resource Board (CARB) air monitors;

2) Explore additional exposure indicators using geostatistical modeling for CHIS respondents in Los Angeles and traffic-related exposure indicators based on residential traffic density (TD) and proximity to roadways for all CHIS 2003 and CHIS 2005 respondents;

3) Examine whether health outcome indicators are associated with spatial and/or temporal variations in pollutant exposures while taking into account other risk factors; and

4) Identify whether the types of health outcomes and the magnitude of associations estimated for our air pollution exposure indicators differ by type of area (e.g., rural and urban) and by sub-populations (e.g., children and the elderly, or racial and ethnic groups).


[1] CDC, National Center for Health Statistics. National Health Interview Survey, 2010. http://www.cdc.gov/asthma/nhis/2010/data.htm. Accessed May 23, 2012. 

[2] UCLA Center for Health Policy Research. California Health Interview Survey, 2009. http://www.askchis.com Exit EPA Disclaimer. Accessed May 23, 2012.

[3] Meng YY, Lombardi C. Asthma and Outdoor Air Pollution. In: Friis R, eds. 2012. The Praeger Handbook of Environmental Health, ABC-CLIO, Inc., Santa Barbara, California.

[4] U.S. Environmental Protection Agency (EPA). (2008) EPA’s 2008 Report on the Environment. National Center for Environmental Assessment, Washington, DC; EPA/600/R-07/045F. Available from the National Technical Information Service, Springfield, VA, and online at https://www.epa.gov/roe.

Summary/Accomplishments (Outputs/Outcomes):

Associations between 12-, 24-, 36-month pollutant concentration averages and asthma health outcomes

We observed positive associations between asthma health outcome indicators and criteria pollutant averages over 1 to 3 years prior to CHIS interview; and in general, positive associations were observed more consistently among adults than children and were similar across the different exposure time periods. Based on pollutant average distributions, we scaled O3 and NO2 by 10 ppb, PM10 by 10 µg/m3, and PM2.5 by 5 µg/m3. Among CHIS 2003 adult respondents ever diagnosed with asthma, we observed positive associations between increased odds of having an asthma attack and a 10 ppb increase in average O3, as well as suggested positive associations between increased odds of having an asthma attack and a 10 µg/m3 increase in average PM10 and a 5 µg/m3 increase in PM2.5 across all exposure time periods. Among CHIS 2003 adults with current asthma, we observed a suggested increase in the odds of experiencing daily/weekly symptoms with increases in 12- and 24-month average PM2.5 concentration. Additionally, we observed positive associations between all four criteria pollutants and the odds of using a daily asthma medication, having two or more work absences due to asthma, and visiting the ED due to asthma within the year prior to the CHIS interview. Specifically, in all exposure time periods, we observed positive associations between increases in odds of daily asthma medication use and increases in average O3 and PM2.5 concentrations; we also observed suggested positive associations between increased odds of daily medication use and increases of average PM10 in all exposure time periods, as well as increases in 12-month average NO2. Across all time periods of exposure, we observed positive associations between increases in the odds of having two or more work absences due to asthma and increases in PM10 averages and suggestive increases in odds of having two or more work absences with increases in all time periods of average NO2 and 12-month average O3 and PM2.5. For all time periods, we observed positive increases in the odds of having an asthma-related ED visit as average PM10 increased and suggested positive associations between increases in odds of having an asthma-related ED visit and increases in average O3 and PM2.5; we observed suggestive increases in the odds of having an ED visit with increases in 12-month and 24-month average NO2. Fewer relationships between criteria pollutants and asthma outcomes were observed among CHIS 2003 children with current asthma. Among children with current asthma, we observed suggested positive associations between increased odds of using a daily asthma medication and increases in 12-month average NO2 as well as positive associations between increased odds of using daily asthma medication and increases in 24- and 36-month average NO2.

Associations between criteria pollutant estimates and asthma outcome associations were weaker and less precise for CHIS 2005 respondents than for CHIS 2003 respondents. Among CHIS 2005 adults with current asthma, we observed suggestive increases in the odds of experiencing daily/weekly symptoms as average 12- and 24-month PM10 increased and a significant positive association between increased odds of experiencing daily/weekly symptoms and increases in average 36-month PM10. We also observed suggested positive associations between increases in the odds of experiencing daily/weekly symptoms and increases in average 12- and 24-month PM2.5 and a significant positive association between increased odds of experiencing daily/weekly symptoms and increased average 36-month PM2.5. Among CHIS 2005 children with current asthma, we observed suggested positive associations between increased odds of missing 2 or more days of school and increased average O3 in all time periods of exposure.

Associations between exposure estimates for criteria air pollutants and asthma-like health outcomes among those without asthma diagnoses, such as wheeze symptoms, having two or more wheeze attacks, and seeking medical help for breathing problems, were observed in adults more than children. Among CHIS 2003 adults who did not have asthma diagnoses, increases in 12-month average O3 and PM10 concentrations were positively associated with increases in the odds of wheeze symptoms across all exposure time intervals, while increased PM2.5 was suggestively associated with an increase in the odds of wheeze symptoms. Among CHIS 2003 adults with asthma-like symptoms, increased 12-month average O3 was suggestively associated, while increases in 24- and 36-month average O3 were significantly associated with increased odds of having two or more wheeze attacks. Across all exposure time periods, increases in average O3 was suggestively associated with increased odds of seeking medical help for breathing problems. Additionally, average 12- and 24-month PM10 increases were suggestively associated, while increased average 36-month PM10 concentration was significantly associated, with increases in the odds of seeking medical help for breathing problems. Among CHIS 2003 children without asthma diagnoses, we observed suggested associations between increases in 12- and 36-month average O3 and increased odds of wheezing, as well as a significant association between increased 24-month average O3 and increased odds of wheezing.

Associations between land use regression (LUR) measures and asthma health outcomes

To explore additional exposure indicators using geostatistical modeling, we examined associations between land use regression (LUR) measures for NO, NO2, and NOX scaled by interquartile range (IQR) among CHIS 2003 and 2005 respondents in Los Angeles County. Among CHIS 2003 adult respondents ever diagnosed with asthma, we observed positive associations between interquartile increases in NO, NO2, and NOX LUR measures and increased odds of reporting asthma attacks in the previous 12 months. Among adults with current asthma, interquartile increases in NO, NO2, and NOX were associated with increased odds of an asthma-related ED visit. The results also suggested a positive association between NO2 and NOX and daily/weekly asthma symptoms among adults with current asthma. We did not observe positive associations between LUR measures for NO, NOX, and NO2 and asthma outcomes among CHIS 2003 children with current asthma or CHIS 2005 respondents with current asthma; however, we observed negative associations between LUR measures for NO, NOX, and NO2 and daily asthma medication use for CHIS 2005 child respondents. These results for CHIS 2005 child respondents are likely unreliable, as the sample size available for children was limited.

Associations between air pollutant concentrations and asthma health outcomes using multilevel modeling

To assess the effects of inter- and intra-community variability in pollutant concentrations among adults with current asthma, we used multi-level modeling to examine associations between asthma outcomes and both mean-concentration levels of Medical Service Study Areas (MSSAs) and the deviation of an individual’s annual average pollutant concentration from his/her assigned MSSA’s annual pollutant mean.

We observed suggested associations between increased odds of having an asthma-related ED visit in the year prior to the CHIS interview and increases in PM10 and PM2.5 MSSA means (between-group exposure effects), as well as increases in the deviation from the PM10 MSSA mean (within-group pollutant exposure effects). Significant associations were observed between increased odds of having daily/weekly symptoms and increases in both the MSSA mean and deviations from the MSSA mean for O3, PM10, and PM2.5. In addition, a significant association was observed between increased odds of missing 2 or more days of school/work due to asthma and increased deviation from the PM10 MSSA mean, while suggested associations were observed between increased odds of missing 2 or more days of school/work and both increases in MSSA mean and increased deviation from the MSSA mean for O3, PM10, and PM2.5.

When assessing between- and within-group exposure effects on daily asthma medication use, significant interactions were found between the CHIS year and pollutant; therefore, MSSA mean concentration effects are reported separately by year for this outcome. Increases in 2003 MSSA pollutant means had stronger associations with daily asthma medication use than increases in 2005 MSSA pollutant means. Among adults with current asthma, associations were significant or near significant between increased odds of daily asthma medication use and increases in 2003 MSSA mean for O3, PM10, and PM2.5. In addition, positive associations were observed between increases in odds of daily asthma medication use and increased deviation from a respondent’s O3, PM10, and PM2.5 MSSA mean.

Associations between annual air pollutant averages and asthma health outcomes stratified by sub-population

To identify whether the types of health outcomes and the magnitude of associations estimated for our air pollution exposure indicators differ by type of area and by sub-population, we examined associations between annual pollutant averages and asthma health outcomes stratified by race, location of residence (urban vs. rural), and age (18-64 years old vs. 65 years and older) among CHIS 2003 respondents with current asthma. We observed associations between annual pollutant averages and asthma health outcomes stratified by race/ethnicity among CHIS 2003 respondents with current asthma. Among Asian/Pacific Islander (API) respondents with current asthma, we observed positive associations between increases in average PM2.5 and increased odds of having an ED visit, having two or more school/work absences, and having daily/weekly symptoms within the year prior to the CHIS interview. Additionally, we observed a suggested association between increases in average PM2.5 and increased odds of daily asthma medication use. We observed positive associations between increases in average NO2 and increased odds of daily medication use, having two or more school/work absences, and having daily/weekly symptoms among API respondents. Among African American respondents with current asthma, increases in annual average PM10 was associated with greater odds of having daily or weekly asthma symptoms, while for Latinos, increased PM10 was associated with greater odds of having an ED visit and using asthma medication daily. Latino respondents with current asthma also had increased odds of daily asthma medication use with increases in annual average O3. Positive associations between increases in annual average O3 and increased odds of missing 2 or more days of school/work were observed among white respondents with current asthma, while for whites ever diagnosed with asthma, an increase in annual average O3 was suggestively associated with an increase in the odds of an asthma attack.

Conclusions:

Based on these findings, we conclude that it is feasible to combine existing environmental monitoring and health survey data to develop indicators signaling the impact of exposures on health outcomes for those with asthma or asthma-like symptoms. In addition to the existing EPA outcome-based environmental health indicators available for asthma such as asthma attack, health outcome indicators such as asthma-related ED visits, absences from school/work, medication use, and frequent asthma symptoms may serve as a new set of health indicators for ozone, particulate matter, and nitrogen dioxide exposures. We also observed associations between exposure estimates for criteria air pollutants and asthma-like health outcomes among those without asthma diagnoses, such as wheeze symptoms, having two or more wheeze attacks, and seeking medical help for breathing problems. Additionally, our findings among CHIS 2003 respondents demonstrated positive associations between exposure indicators developed through geostatistical modeling (e.g., LUR) for NO, NO2, and NOX and the asthma outcomes of interest. This finding illuminates the potential benefits of incorporating other exposure indicators in addition to indicators based on air monitoring data alone to more accurately assess pollutant exposures, especially for exposure indicators that focus on traffic emissions. Furthermore, positive associations between ED visits due to asthma, daily/weekly asthma symptoms, and missing 2 or more days of school/work were observed as O3, PM10, and PM2.5 exposure increased both between- and within-MSSAs for CHIS 2003 and 2005 respondents with current asthma. These results highlight the community level impact of air pollution on asthma outcomes and the importance of policies that decrease air pollution exposure for communities as a whole. However, further research is needed to refine these indicators and to determine whether theses health outcome indicators would be valid for other parts of the country. Finally, differences in health outcomes associated with air pollutant exposure were observed across racial/ethnic groups, highlighting the importance of protecting vulnerable populations from air pollutant exposure and the subsequent effect on asthma and asthma-related health outcomes.

References:

CDC, National Center for Health Statistics. National Health Interview Survey, 2010. http://www.cdc.gov/asthma/nhis/2010/data.htm. Accessed May 23, 2012.

Berhane, K., W. J. Gauderman, et al. (2004). Statistical issues in studies of the long term effects of air pollution: The Southern California Childrens Health Study (with discussion). Statistical Science 19(3): 414-449.

Checkley, W., K. P. West, Jr., et al. (2011). Supplementation with vitamin A early in life and subsequent risk of asthma. The European Respiratory Journal : Official Journal of the European Society for Clinical Respiratory Physiology

Gunier, R. B., A. Hertz, et al. (2003). Traffic density in California: socioeconomic and ethnic differences among potentially exposed children. Journal of Exposure Analysis and Environmental Epidemiology 13(3): 240-246.

Meng YY, Lombardi C. Asthma and outdoor air pollution. In: Friis R, eds. 2012. The Praeger Handbook of Environmental Health, Santa Barbara, California:  ABC-CLIO, Inc.

Reynolds, P., J. Von Behren, et al. (2004). Residential exposure to traffic in California and childhood cancer. Epidemiology 15(1): 6-12.

Su, J. G., M. Jerrett, et al. (2009). Predicting traffic-related air pollution in Los Angeles using a distance decay regression selection strategy. Environmental Research 109(6): 657-670.

UCLA Center for Health Policy Research. California Health Interview Survey, 2009. http://www.askchis.com. Accessed May 23, 2012.

U.S. Environmental Protection Agency (EPA). (2008) EPA’s 2008 Report on the Environment. National Center for Environmental Assessment, Washington, DC; EPA/600/R-07/045F. Available from the National Technical Information Service, Springfield, VA, and online at https://www.epa.gov/roe.

Journal Articles:

No journal articles submitted with this report: View all 3 publications for this project

Supplemental Keywords:

Health outcome indicators, asthma, asthma-like symptoms, criteria pollutant, mobile sources, risk, health effects, ecological effects, vulnerability, public policy, decision making, public good, Bayesian, socio-economic, epidemiology, geostatistical modeling, Northwest, California, CA, EPA Region 9

Progress and Final Reports:

Original Abstract
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  • 2009 Progress Report
  • 2010 Progress Report
  • 2011