Pollution and Parks

A recent report by the National Parks Conservation Association (NPCA) has reported that "... 96% of 417 national parks [includes all different units of the NPS, such as parks, monuments, seashores, etc.] assessed are plagued by significant air pollution problems in a least one of four categories."  The different categories considered in the study include:

1. Unhealthy air - air which is unhealthy to breathe.
2. Harm to nature - air pollution which damages sensitive species and habitats.
3. Hazy skies - pollution which impacts the view, the aesthetics of a park.
4. Climate change - parks where climate change, and subsequent impacts (i.e., fires, floods, intense storm events), pose serious threats. 

"Air pollution is harming public health, obscuring views and degrading our nation's most precious park sites, from Glacier National Park in Montana to the Natchez Trace Parkway in Tennessee to Cuyahoga Valley National Park in Ohio." (NPCA, 2019).

The Clean Air Act (passed in 1970, amended in 1990) made possible decades of improvements in air quality in the USA.  Yet, in just two years or so, the Trump administration's policies have reversed this positive trend.  Air quality is getting worse, including in our national parks.  Four of the most polluted parks are in California, including Joshua Tree (which I recently visited), Mojave, Sequioa (which I have also visited), and Kings Canyon National Parks.  Pollution levels in these parks are often comparable to large urban areas such as Los Angeles, at least based on the data and information presented in the study by NPCA (2019).

And another study, by Keiser et al., published in 2018 in Science Advances, found that the "... average annual ozone concentrations in national parks are statistically indistinguishable from those in metropolitan areas."  This study included data for 33 national parks and 20 of the nation's largest metropolitan areas for the years between 1990 and 204.  They also reported that exceedance days at some parks are higher than for nearby metropolitan areas.  For example, the exceedance days at Sequoia National Park were actually higher than for Los Angeles in all but two years since 1996.  Exceedance days, as defined by the US EPA, are the number of days per year where the maximum daily 8-hour level of some pollutant exceeds some predetermined level, a level determined by what is considered to "unhealthy for sensitive groups."  For low-level ozone (which is different from the ozone level in the stratosphere, high in the atmosphere), the primary pollutant considered in this study, has a threshold level of 70 parts per billion (ppb).  The authors also reported that there is a statistically significant, and negative, relationship between ozone pollution (monthly mean daily 8-hour maximum ozone concentration), and visitations at parks included in the study.  In other words, between the years 1990 to 2014, when ozone levels were high, fewer people visited the parks.  This study only included data up to and including 2014.  What might things look like now, in 2019, after two years of Trump and the significant roll-backs of environmental regulations, lack of regulatory compliance, and significant increases in drilling, fracking, and mining taking place all over the country, including in areas adjacent to our national parks.  This is bad, for us, when visiting these parks, and for the species and habitats found in these amazing places, our national parks. 

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