Data Showing Current Impacts

Monitoring Location with Maximum 3-Month SUM W126 Greater Than or Equal to 7 ppm-hrs (2007)

The EPA recommends that the range should be established between 7-21 ppm hours, so that the W126 can be less than that. The W126 index is used as a metric to measure harm to vegetation due to ozone pollution.

Upon looking at this table, we see that the three national parks located in the Sierra Nevada (Sequoia and Kings Canyon - Ash Mountain & Lower Kaweah, and Yosemite) all surpass the upper range of 21 ozone ppm-hour. From this, we are able to see that such human impacts are quite apparent in the Sierra Nevada region, as the ozone levels at these locations are substantially high compared to the other national parks.

Ozone occurs when sunlight generates photochemical reactions which involve nitrogen oxides and volatile organic hydrocarbons VOC, and carbon monoxide, which usually are created from gas engines, automobiles, and fossil fuel use.

Ozone has a negative impact on plants as it can cause numerous symptoms to occur such as chlorosis and necrosis. It can also cause symptoms such as flecks, stipples bronzing and reddening. Essentially, ozone has a detrimental effect on plants.

Source: "Air Quality in National Parks: 2008 Annual Performance & Progress Report" Natural Resource Report NPS/NRPC/ARD/NRR—2009/151 by the National Park Service - U.S. Department of the Interior [http://www.nps.gov/yose/naturescience/upload/AQ.Trends.Parks.2008.pdf]

"Related Topics." Plant Science Research : Ozone effects on plants. N.p., n.d. Web. 20 Nov. 2013. <http://www.ars.usda.gov/Main/docs.htm?docid=12462>.