The Oliver Robinson bribery trial, in which guilty verdicts were issued for officials of Drummond Coal Co. and its law firm, Balch & Bingham, revealed a gritty episode about avoiding environmental cleanup in North Birmingham. But there’s a bigger dirty picture.

The vast majority of Jefferson County’s 31 major sources of pollution – those emitting enough pollution to require a permit under Title V of the Clean Air Act – are located in low-income areas, a BirminghamWatch analysis found.

The findings show 71 percent of the major pollution sources are in areas with incomes below the median income for the county.

Only one primary source of pollution is in a neighborhood with a median household income greater than 110 percent of the county median.

Residents of the same low-income areas also often are largely African American. Research has shown that economically depressed populations can be more heavily affected by the negative health effects of air pollution.

Poor air does not equally strike everyone in the Birmingham area, raising issues of environmental justice. Read more.

Thirty-one industries, businesses and other operations in Jefferson County are considered possible large sources of pollution and issued operating permits that recognize that. In total 190 entities – from colleges to funeral homes to dry cleaners – hold air emission permits of some type. Read more.