Washington, Philadelphia, St. Louis, Houston and Cleveland are among the areas getting a one-year extension on 2008 federal ozone standards, the Environmental Protection Agency announced.
The major metropolitan areas are among the areas that did not meet the 75 parts per billion standard handed down by the Bush administration in 2008. The cities were supposed to be in compliance by July 20, 2015.
In addition to those five cities, Pittsburgh, San Luis Obispo, Calif., and Sheboygan County, Wis., also were granted one-year extensions, the EPA said Monday.
Ozone is the primary component in smog and typically concentrates in high population areas. It particularly affects people with asthma, children and the elderly. The EPA announced in October it would lower the standard from 75 parts per billion to 70 parts per billion.
Seventeen metro areas reached attainment levels by the deadline, according to the EPA.
Eleven metro areas failed to comply and are being reclassified as moderate ozone attainment areas. That new classification means they have three years to submit a State Implementation Plan to bring down the amount of ozone.