Source: POLITICO'S MORNING AGRICULTURE, 8/15/18

Air quality in national parks was about the same as in the nation's 20 largest cities from 1990 to 2014, according to a new study published in the journal Science Advances. Sequoia National Park, for example, had similar high ozone concentration levels as Los Angeles, the metropolitan area with the highest amount of air pollution in the country.

To read the study, click here.