You’d think national parks would be the cleanest places in America — but think again.
From choking wildfire smoke to smog creeping in from nearby cities, even our most iconic wilderness escapes aren’t safe from pollution.
Nearly every park in the system is now battling haze, ozone, and noise. Some are downright dangerous on bad days.
Here’s who tops the list — and why.
Sequoia and Kings Canyon — Ground Zero for Park Pollution
These California parks top every pollution list. They’re hit hardest by smog from Central Valley farms, vehicle traffic, and wildfire smoke. Giant sequoias — some over 3,000 years old — are now suffering from chronic ozone exposure and nitrogen buildup.
Joshua Tree — Strangled by Desert Smog
Ozone levels here often rival those of major cities. Despite its remote location, Joshua Tree gets hammered by regional pollution drifting in from Los Angeles and surrounding highways. It’s one of the worst ozone hotspots in the park system.
Mojave National Preserve — Wildfire Smoke Magnet
Massive in size and stunningly remote, Mojave has become a smoke trap. Nearby wildfires routinely dump particulates into the air, especially in summer. Visibility and air quality plummet for weeks at a time.
Yosemite — Stunning, But Not So Clean
Yosemite’s iconic views are often marred by haze from pollution in the San Joaquin Valley and regional fires. Visibility has been reduced by up to 70%, and ozone levels here exceed federal health standards far too often.
Carlsbad Caverns — Air Pollution Underground
Even this underground marvel in New Mexico isn’t immune. Air pollution from regional oil and gas operations, plus wildfire smoke, penetrates the cavern system. Elevated ozone levels have been recorded at the surface entrance.
Death Valley — Irony in Extremes
You’d think the hottest, driest place in America would be spared — but no. Wildfire smoke and cross-border pollution drift in, turning this desert into an unlikely air-quality battleground.
Indiana Dunes — Industry’s Backyard
This midwestern park sits next to steel mills, rail yards, and highways. It regularly records some of the worst ozone levels in the entire park system. Industrial and traffic pollution make it a persistent hotspot.
Guadalupe Mountains — Oil & Gas Fallout
Nestled near the Permian Basin, Guadalupe Mountains faces air quality issues from nearby drilling and flaring. Ozone and haze are on the rise, and recent wildfire seasons have only made things worse.
Rocky Mountain National Park — Western Smoke Hub
Air quality here has tanked in recent years thanks to wildfire smoke drifting from California and the Pacific Northwest. Some summers see more unhealthy air days here than in Colorado cities.
White Sands — A Growing Concern
Once considered pristine, White Sands now faces increasing air pollution from nearby oil fields and regional wildfire smoke. It hasn’t hit “worst in the nation” yet — but trends suggest it could climb the list fast.
