Assessing exposure to unconventional natural gas development: using an air pollution dispersal screening model to predict new-onset respiratory symptoms.

Various exposure estimates have been used to assess health impact of unconventional natural gas development (UNGD). The purpose of this study was to (1) use an air pollution dispersal screening model and wind direction to characterize the air emissions from UNGD facilities at each residence and (2) assess association of this exposure estimate with respiratory symptoms. Respiratory symptoms were abstracted from health records of a convenience sample of 104 adults from one county in southwestern PA who had completed a standard clinical interview with a nurse practitioner. Using publicly available air emission data, we applied a "box" air pollution dispersion screening model to estimate the median ambient air level of CO, NOx, PM 2.5, VOCs, and formaldehyde at the residence during the year health symptoms were reported. Sources and median emissions were categorized as north, south, east, or west of the residence to account for the effect of wind direction on dispersion. Binary logistic regression was performed for each respiratory symptom. Number of sources had varying magnitudes of association with some symptoms (i.e., cough, shortness of breath, and "any respiratory symptom") and no association with others (i.e., sore throat, sinus problems, wheezing). Air emissions were not associated with any symptom.