By Tim Halliday, John Lynham and Aureo de Paula
Kīlauea volcano is the largest stationary source of sulfur dioxide (SO₂) pollution in the United States of America. The SO₂ that the volcano emits eventually forms particulate matter, another major pollutant. In a recent project, we use this exogenous source of pollution variation to estimate the impact of particulate matter and SO₂ on emergency room admissions and costs in the state of Hawai‘i.
To accomplish this, we employ two sources of data. The first is measurements of air quality collected by the Hawai‘i Department of Health taken from various monitoring stations across the state. The second is data on emergency room utilization due to cardio-pulmonary reasons which we obtained from the Hawai‘i Health Information Corporation. An important feature of our study is that our cost data are more accurate than the cost measures used in much of the literature. We then merged these data by region and day to obtain a comprehensive database of air quality and medical care utilization in the State of Hawai‘i. Importantly, we employed coarse geographic information on the patients’ residence (as opposed to the hospital in which they were admitted) when computing the utilization time series by region to ensure that our utilization measures corresponded more accurately with the pollution exposure. Using the merged database, we then employed regression techniques in which we related ER utilization and charges to measures of exposure to particulates and SO2 while controlling for comprehensive seasonal patterns and regional effects.
We find strong evidence that particulate pollution increases pulmonary-related hospitalization. Specifically, a one standard deviation increase in particulate pollution leads to a 2-3% increase in expenditures on emergency room visits for pulmonary-related outcomes. However, we do not find strong effects for pure SO₂ pollution or for cardiovascular outcomes. We also find no effect of volcanic pollution on fractures, our placebo outcome. Finally, the effects of particulate pollution on pulmonary-related admissions are most concentrated among the very young. Our estimates suggest that, since the large increase in emissions that began in 2008, the volcano has increased healthcare costs in Hawai‘i by approximately $6,277,204.
These estimates provide evidence of some of the external costs of particulate pollution. Importantly, other studies have had a difficult time unraveling the effects of particulate pollution from other types of pollution such as carbon monoxide because they tend to be highly correlated. In contrast, in our data, the correlation between particulate pollution and other pollutants (aside from SO2, of course) is considerably smaller than the other literature on the topic that largely relies on manmade sources of pollution. In this sense, we provide one of the best available estimates of the pure impact of particulate pollution on human health.
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