Ozone timeline

  • First ozone standard

    First ozone standard enacted in the U.S., a year after Congress passes the Clean Air Act and President Richard Nixon launches the U.S. Environmental Protection Agency.

  • Auto makers take action

    Major auto manufacturers release cars with catalytic converters, a device that will substantially reduce pollution leading to ozone.

  • New standards face pressure

    Pressure mounts on the EPA over its 80 parts-per-billion ozone standard, with both the Carter administration’s inflation-fighters and industry groups calling for it to be loosened.

  • EPA yields, loosens standard

    The EPA raises its ozone threshold to 120 ppb.

  • Back to 80 ppb

    The EPA tightens the ozone threshold back to 80 ppb over industry warnings that bans of barbecues and lawnmowers could follow.

  • Supreme Court steps in

    The U.S. Supreme Court rules that, counter to industry groups’ wishes, the EPA must consider only what is safe to breathe when it sets its ozone standard, not cost.

  • EPA considers tougher standards

    With research showing harms from lower amounts of ozone, the EPA’s independent scientific advisory panel on ozone unanimously recommends the standard be tightened to a level between 60 and 70 ppb.

  • New standard prompts criticism

    EPA sets the ozone standard at 75 ppb, drawing a rebuke from its advisory panel that the level “fails to satisfy the explicit stipulations of the Clean Air Act that you ensure an adequate margin of safety for all individuals.”

  • Obama's EPA

    EPA, now under President Barack Obama, decides to revisit the ozone standard.

  • Obama intervention

    As the EPA prepares to set a tighter standard, Obama intervenes, saying it should not be changed yet because it is due to be reconsidered in 2013 — after a presidential election year

  • Health groups sue EPA

    With no ozone reconsideration underway, the American Lung Association and other groups sue the EPA.

  • New standards by Oct. 2015

    After a federal judge sets deadlines for action, the EPA proposes to tighten its standard by October 2015.