The updates will phase in deadlines for controlling emissions, with different timetables for tanks coming online after April 12 of this year — when the change was first proposed — and those that came on before that date.
Additionally, the new standards remove controls for the tanks if owners and operators can prove that they emit less than four tons of volatile organic compounds a year, and clarify protocols and other measures of the original rule.
The organic compounds the tanks emit can form ozone, which can lead to health problems.
Storage tanks can also emit other air pollutants like benzene and hexane, which can cause cancer and other ailments.
The EPA sets limits on emissions for storage tans that emit six or more tons of collative organic compounds, requiring that they reduce their output by 95 percent.