An examination of historical air pollutant emissions from us petroleum refineries

Criteria and hazardous air pollutant emissions from petroleum refineries in the US have decreased over the last 20 yr despite increasing crude density, changes in sulfur concentrations, increasingly stringent product specifications, and overall increase of refinery production of major fuel types. Refinery emissions of criteria air pollutants have decreased as much as 80% from 1990 to 2010. Emissions of hazardous air pollutants and their associated toxicity hazard potential have decreased nearly 70%. Furthermore, the emissions are not correlated with changes in crude oil sulfur content or density. Trends in annual criteria and hazardous air pollutant emissions and in crude oil density and sulfur content are compared to assess potential relationships between crude quality and refinery emissions. The potential toxicity of hazardous air pollutant emissions is evaluated using USEPA‐derived toxicity criteria and then trended to demonstrate the overall reduction in toxicity hazard potential that has occurred.