During a hike in the Great Smoky Mountains National Park in 1995, Don Barger climbed Chilhowee Mountain hoping to gaze across the valley below. All he saw was a wall of gray haze.

An analysis of data from 1999 through 2023 shows 93% of parks and wilderness areas saw improved air quality on clear days.

Spark curiosity with the National Geographic Little Kids Book Bundle this Earth Month—perfect for budding explorers aged 3–5! Get 6 exciting issues of National Geographic Little Kids magazine ...