With vehicle travel down more than 40% during the coronavirus lockdowns, new articles abound about how much cleaner our air has become. However, the real data and the implications for air quality regulations are not as clear as the headlines imply.

Key Points:

  • The decline in vehicle travel during March and April 2020 of over 40% nationwide provided an unintended experiment on the effects of vehicle emissions on U.S. air quality.
  • News headlines identifying the drop in vehicle travel as the primary cause of better air quality in U.S. cities during March and April 2020 are not supported by the data.
  • What the data show is that U.S. cities have some of the cleanest air in the world. Weather and natural pollution sources have at least as large of an effect on U.S. pollution levels as human emissions.
  • The lack of significant improvement in air quality during this major reduction in activity is evidence that tighter air quality standards and greater use of electric vehicles will yield very few environmental improvements.