Pollution and regional variations of lung cancer mortality in the United States

The aims of this study were to identify counties in the United States (US) with high rates of lung cancer mortality, and to characterize the associated community-level factors while focusing on particulate-matter pollution.

We performed a descriptive analysis of lung cancer deaths in the US from 2004 through 2014. We categorized counties as "clustered" or "non-clustered" - based on whether or not they had high lung cancer mortality rates - using novel geospatial autocorrelation methods. We contrasted community characteristics between cluster categories. We performed logistic regression for the association between cluster category and particulate-matter pollution.

Among 362 counties (11.6%) categorized as clustered, the age-adjusted lung cancer mortality rate was 99.70 deaths per 100,000 persons (95%CI: 99.1-100.3). Compared with non-clustered counties, clustered counties were more likely in the south (72.9% versus 42.1%, P<0.01) and in non-urban communities (73.2% versus 57.4, P<0.01). Clustered counties had greater particulate-matter pollution, lower education and income, higher rates of obesity and physical inactivity, less access to healthcare, and greater unemployment rates (P<0.01). Higher levels of particulate-matter pollution (4th quartile versus 1st quartile) were associated with two-fold greater odds of being a clustered county (adjusted OR: 2.10; 95%CI: 1.23-3.59).

We observed a belt of counties with high lung mortality ranging from eastern Oklahoma through central Appalachia; these counties were characterized by higher pollution, a more rural population, lower socioeconomic status and poorer access to healthcare. To mitigate the burden of lung cancer mortality in the US, both urban and rural areas should consider minimizing air pollution.