Introduction• Asthma prevalence (2013): 7.0% of U.S. adults

and 11.5% of Michigan adults (CDC, 2015).

• Fine particulate matter (PM2.5) associated with increased asthma morbidity (Delfino et al., 2014; Slaughter et al., 2003).

Methods• A serial cross-sectional study design

examined the association between annual county-level air pollution and prevalence of asthma in Kent County, MI.

• Asthma and covariates were assessed using data from the Behavioral Risk Factor Surveillance System (BRFSS) Selected Metropolitan Area Risk Trends (SMART) for Kent County for 2005-2012.

• Annual PM2.5 concentration and ambient temperature data was from retrieved from AirData online database for 2004-2012.

• Publicly available data did not require consent from the individuals, per the Grand Valley State University Human Research Review Committee.

• Poisson regression was used to identify whether annual PM2.5 concentration is associated with the prevalence of asthma.

• Analyses were repeated for a one-year lag in the PM2.5 data.

• Statistical analyses performed using SAS v9.4 (Cary, NC).

AcknowledgmentsI would like to thank Jeffrey Wing, PhD, MPH for his assistance with this project, including SAS training and statistical analyses.

Results Discussion & Conclusions• First study to analyze the association

between PM2.5 and adult asthma prevalence in Kent County, MI.

• Adjusted for numerous health, demographic, and environmental confounders, in order to reduce bias in the models presented.

• Large, representative sample from Kent County, MI over an eight year timespan.

• A suggestive association between same-year PM2.5 and asthma was observed when controlling for confounding factors.

• Limitations • Cross-sectional research design• Limited COPD and race/ethnicity data• One-year lag period analysis• Other studies note associations

between 7-14 days (Kim et al., 2012; Slaughter et al., 2003).

• Suggestive association indicates importance low ambient PM2.5 concentration has on adult asthma prevalence in Kent County.

Brenton L. SpikerGrand Valley State University

ReferencesCenters for Disease Control and Prevention. (2015). Asthma: Most recent

asthma data. Retrieved from http://www.cdc.gov/asthma/most_recent_data.htm

Delfino, R. J., Wu, J., Tjoa, T., Gullesserian, S. K., Nickerson, B., & Gillen, D. L. (2014). Asthma morbidity and ambient air pollution. Epidemiology, 25(1), 48–57. http://doi.org/10.1097/EDE.0000000000000016

Kim, S. Y., Peel, J. L., Hannigan, M. P., Dutton, S. J., Sheppard, L., Clark, M. L., & Vedal, S. (2012). The temporal lag structure of short-term associations of fine particulate matter chemical constituents and cardiovascular and respiratory hospitalizations. Environmental Health Perspectives, 120(8), 1094–1099. http://doi.org/10.1289/ehp.1104721

Slaughter, J. C., Lumley, T., Sheppard, L., Koenig, J. Q., & Shapiro, G. G. (2003). Effects of ambient air pollution on symptom severity and medication use in children with asthma. Annals of Allergy, Asthma & Immunology, 91(4), 346–353. http://doi.org/10.1016/S1081-1206(10)61681-X

Annual PM2.5 concentration and asthma prevalence in Kent County, Michigan

Note: Asthma data is adapted from the Selected Metropolitan Area Risk Trends (SMART) data for Kent County, from the Behavioral Risk Factor Surveillance Study (BRFSS), for the associated years in the table. Particulate matter and maximum temperature data is adapted from the AirData database, available for Grand Rapids, Michigan. Temperature is reported in degrees Centigrade (oC).a Proportions were calculated using all respondents, including responses of “Don’t Know/Not Sure.” b Kent County BRFSS SMART data unavailable for 2004 or 2006.

Table 1

BRFSS Asthma and PM2.5 data for Kent County, MI 

YearEver Told

Have Asthma

Never Told Have

Asthma

Proportion with

Asthma (%)a

Annual Mean PM2.5

(µg/m³)

AverageMaximum

Temperature (oC)

2004 .b .b - b 12.01 14.97

2005 92 586 13.57 13.40 14.86

2006 .b .b -b 12.84 8.41

2007 53 352 13.98 12.82 17.26

2008 50 422 10.57 10.61 14.96

2009 78 388 16.74 10.52 15.04

2010 57 388 12.78 9.65 16.88

2011 98 652 13.01 9.47 16.21

2012 73 450 13.88 9.65 18.42

Figure 1. Annual adult asthma proportion and annual mean PM2.5 concentration for Kent County, Michigan from 2005-2012. 2006 Kent County BRFSS SMART data not available.

• 3,721 respondents in the Kent County, MI SMART BRFSS from 2005-2012 (Table 1 and Figure 1).

• Same-year statistical analysis:• The simple (unadjusted) model: 10µg/m3

increase in PM2.5 was associated with approximately 38.5% increase in the prevalence of asthma in Kent County, MI (p = 0.063).

• The final adjusted model: 10µg/m3 increase in PM2.5 was associated with approximately 35% increase in the prevalence of asthma in Kent County, MI (p = 0.085).

• One-year lag analysis:• The simple model: 10µg/m3 increase in PM2.5

was associated with a 13% lower odds of asthma in Kent County, MI (p = 0.122).

• The final adjusted model: 10µg/m3 increase in PM2.5 was associated with a 12% lower odds of asthma in Kent County, MI (p = 0.156).

Table 2

Asthma Prevalence Ratio Models

Model PR 95% CI p-value

Unadjusted a 1.39 0.98, 1.95 0.0627

Adjusted b 1.35 0.96, 1.90 0.0850

Lag Unadjusted a 0.87 0.73, 1.04 0.122

Lag Adjusted b 0.88 0.74, 1.05 0.156

Note: Prevalence ratio (PR) is represented by a 10µg/m3 increase in PM2.5.a Unadjusted models include average annual PM2.5, year, and average annual maximum temperature. b Adjusted models includes PM2.5, year, average annual maximum temperature, age, diabetes, smokers, sex, household income, highest completed education, employment, and healthcare status.

Objective• Analyze association between adult

asthma prevalence and annual PM2.5 concentration in Kent County, MI for 2005-2012.