142nd APHA Annual Meeting and Exposition

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Exploring drivers of asthma in Louisville with spatially-explicit, real-time data: The environmental perspective

142nd APHA Annual Meeting and Exposition (November 15 - November 19, 2014): http://www.apha.org/events-and-meetings/annual
Tuesday, November 18, 2014 : 1:10 PM - 1:30 PM

Meredith Barrett, PhD , Propeller Health, San Francisco, CA
Olivier Humblet, ScD , Propeller Health, San Francisco, CA
Justine Marcus, BA , Propeller Health, San Francisco, CA
Ted Smith, PhD , Economic Growth and Innovation, Louisville Metro Government, Louisville, KY
David Van Sickle, PhD , Propeller Health, Madison, WI

In Louisville, Kentucky, a history of industrial activity and poor air quality has contributed to an adult asthma prevalence of 15%. Local asthma surveillance activities, which rely upon limited data including asthma hospitalizations and prevalence assessed by national surveys, do not provide spatially-defined information indicating where and when asthma exacerbations occur.


We aimed to determine the community-level drivers of asthma exacerbations in real time and space. The specific objectives included: 1) studying associations between ambient air pollutant variability and asthma exacerbations, 2) identifying hotspots of high density inhaler use, 3) predicting areas of high risk, and 4) generating models to evaluate the impact of public health interventions.


Active Louisville participants (n=140) tracked their rescue inhaler for 13 months with a GPS-enabled sensor. This sensor passively collected the time and precise location of each inhaler use. Using GIS and spatial tools, we mapped population-level asthma hotspots and extracted georeferenced environmental, climatic and socioeconomic data for each inhaler event.


Sensors collected 5,430 inhaler events, which were merged with over 40 socioeconomic and environmental datasets. The daily frequency of inhaler use was significantly correlated with concentrations of carbon monoxide, nitrogen dioxide, and particulate matter; tree and weed pollen; lower wind speed; and southerly and easterly winds. Hotspots were identified, and ecological niche models predicted areas of high risk, influenced predominantly by impervious surface, PM2.5 and proximity to emission sources. We predicted a 27% reduction in high risk areas for inhaler usage if Louisville were to reduce PM2.5 by 10% across the region.


Tracking where and when asthma symptoms occur can support asthma surveillance, improve understanding of environmental drivers, target interventions and raise public awareness. Moving forward, the program should address methodological limitations to ensure hotspots are representative of asthma severity, irrespective of clustered participation.

Learning Areas:

Environmental health sciences
Public health or related research

Learning Objectives:
Describe the history of air quality and the current asthma burden in Louisville. Compare the value of sensor-collected asthma data for community asthma surveillance with historic data from national surveys and healthcare utilizations. List the associations between inhaler use and several environmental drivers in Louisville. Identify asthma hotspots across Louisville and Jefferson County.

Keyword(s): Geographic Information Systems (GIS), Environmental Health

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: Meredith Barrett, PhD, has over 15 years of experience in environmental science and health research, and has studied the impacts of environmental change on both infectious and chronic disease. She was a Robert Wood Johnson Foundation Health & Society Postdoctoral Scholar at the University of California Berkeley and UC San Francisco from 2011-2013, where she first collaborated on this Louisville project. She joined Propeller health as VP of Science and Research in September 2013.
Any relevant financial relationships? Yes

Name of Organization Clinical/Research Area Type of relationship
Propeller Health Chronic Respiratory Disease Employment (includes retainer) and Stock Ownership

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.