- The document examines the association between annual PM2.5 levels and adult asthma prevalence in Kent County, Michigan from 2005-2012 using BRFSS data. - A 10μg/m3 increase in same-year PM2.5 was associated with a 35% increase in asthma prevalence, though this finding was only suggestive. - A one-year lag analysis found a non-significant negative association between PM2.5 and subsequent asthma prevalence.

1. 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).
Acknowledgments
I 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. Spiker
Grand Valley State University
References
Centers 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
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
Year
Ever Told
Have
Asthma
Never
Told
Have
Asthma
Proportion
with
Asthma
(%)a
Annual
Mean
PM2.5
(µg/m³)
Average
Maximum
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.