How Does City Pollution Compare to National Parks?

It would be logical to assume that in comparison to levels of pollution found in urban metropoles, the air quality in national parks would be consistently higher. That’s not the case, however, according to a new study conducted by researchers from Cornell University in the United States.

After analysing levels of ozone contamination in all members of the National Park Service (NPS), the team found that average amounts of the pollutant were indistinguishable in the parks from the 20 biggest cities in the country. Perhaps even more concerningly, air quality in cities has been improving at a far faster rate than in parks, suggesting more must be done to eliminate pollution in these areas.

Surprising results

The report, which was published in the journal Science Advances last month, assessed ozone levels in national parks between the years 1990 and 2014. They found that the parks suffered similar levels of ozone pollution to the 20 biggest cities in the USA, with some of them showing particularly high levels of contamination.

For example, Sequoia National Park in California endured more days where ozone concentrations exceeded recommended “safe” levels in all but two years since 1996 than any urban area in the country. Nearby Joshua Tree National Park also had a similar number of ozone exceedance days as New York City, highlighting how the air in these supposedly uncontaminated places is just as dirty (at least in terms of ozone pollution) as anywhere in the country.

Cities improving more quickly than parks

Another concerning discovery made by the study was the different rates at which both areas are cleaning up their airways. The Regional Haze Rule was introduced in 1999 to try and improve air quality and reduce transport-related pollution, especially in urban strongholds. While it appears to have had success in both regions, it has been more limited in the parks than in the cities.

For example, in the first 10 years that the researchers looked at, Joshua Tree had an average of 105 ozone exceedance days, while NYC suffered marginally more with an average of 110. But in the years between 2001 and 2014, the latter’s count had fallen to 78, while Joshua Tree still endured 101 on average. This is emblematic of the wider situation, as well; the metropolitan area average fell from 53 to just 18 days per year (a reduction of almost two thirds), while the parks average only fell from 27 to 16 (a mere 40%).

Guilty by association

The reason for the parks’ poor air quality? Proximity to major sources of pollution, such as mining hotspots, coal-fired power plants and other industrial strongholds. Acadia National Park and Grand Canyon National Park both point the finger at nearby sources of pollutants and the pollution-trapping natural terrain of the area as the cause of their air quality woes.

Of course, it must be remembered that these new findings only deal in terms of ozone concentrations, not other contaminants. However, there are plenty of reasons to be concerned about ozone pollution on its own, so those wishing to visit national parks are advised to check the forecast on the site’s webpage, Twitter feed or other reliable source before setting off.