- Air quality at Point Reyes National Seashore
- Related references
Air quality at Point Reyes National Seashore
Most visitors expect clean air and clear views in parks. Point Reyes National Seashore (NS), California is home to rocky headlands rising above the Pacific ocean, sand beaches, open grasslands, brushy hillsides, and forested ridges. The seashore enjoys relatively good air quality due to the prevailing westerly marine winds, but sometimes winds from the San Francisco Bay Area can bring air pollution to the seashore. Air pollutants blown into the park can harm natural and scenic resources such as soils, surface waters, plants, wildlife, and visibility. The National Park Service works to address air pollution effects at Point Reyes NS, and in parks across the U.S., through science, policy and planning, and by doing our part.
Many visitors come to Point Reyes NS to enjoy views of the coast from this narrow, steep-ridged peninsula. Natural fog and humidity sometimes form over the ocean and blanket the seashore, obscuring spectacular vistas, and occasionally the vistas are obscured by human-caused haze. Haze reduces how well and how far people can see. Visibility reducing haze is caused by tiny particles in the air, and these particles can also affect human health. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze. Organic compounds, soot, and dust reduce visibility as well. Significant improvements in park visibility have been documented since the 1990’s. Still, visibility in the park needs improvement to reach the Clean Air Act goal of no human caused impairment.
- Reduced visibility on some days due to human-caused haze and fine particles of air pollution;
- Reduction of the average natural visual range from about 90 miles (without the effects of pollution) to about 70 miles because of pollution at the park;
- Reduction of the visual range from about 50 miles to below 35 miles on high pollution days.
Visit the NPS air quality conditions and trends website for park-specific visibility information. Point Reyes NS has been monitoring visibility since 1989. View a live air quality webcam, and explore air monitoring »
Nitrogen and sulfur
Nitrogen and sulfur compounds deposited from the air may have harmful effects, including acidification, on soils, lakes, ponds, and streams. Some plants are sensitive to acidification, search for acid-sensitive plant species found at Point Reyes NS.
Excess nitrogen can also lead to nutrient enrichment, a process that changes nutrient cycling and alters plant communities. The arid and semi-arid ecosystems in Point Reyes NS are particularly vulnerable to changes caused by nitrogen deposition. Although atmospheric nitrogen inputs are relatively low in the area (Sullivan et al. 2001), in other areas of California nitrogen deposition plays an important role in the ongoing replacement of native plant species with exotic, invasive plant species in coastal sage scrub communities (Fenn et al. 2003).
Healthy ecosystems can naturally buffer a certain amount of pollution, but as nitrogen and sulfur accumulate, a threshold is passed where the ecosystem is harmed. “Critical load” is a term used to describe the amount of pollution above which harmful changes in sensitive ecosystems occur (Porter 2005). Nitrogen deposition exceeds the critical load for one or more park ecosystems (NPS ARD 2018).
Visit the NPS air quality conditions and trends website for park-specific nitrogen and sulfur deposition information.
At ground level, ozone is harmful to human health and the environment. Ground-level ozone does not come directly from smokestacks or vehicles, but instead is formed when other pollutants, mainly nitrogen oxides and volatile organic compounds, react in the presence of sunlight.
Over the course of a growing season, ozone can damage plant tissues making it harder for plants to produce and store food. It also weakens plants making them less resistant to disease and insect infestations. Some plants are more sensitive to ozone than others. Ozone concentrations and seasonal exposures at Point Reyes NS are unlikely to cause plant injury or reduced growth (Sullivan et al. 2001). However, several park species, including Artemisia douglasiana (Douglas’ sagewort) and Sambucus mexicana (blue elderberry), are known to be sensitive to ozone. Search for more ozone-sensitive plant species found at Point Reyes NS.
Visit the NPS air quality conditions and trends website for park-specific ozone information.
Mercury and toxics
Airborne mercury, and other toxic air contaminants, when deposited are known to harm birds, salamanders, fish and other wildlife, and cause human health concerns. These substances enter the food chain and accumulate in the tissue of organisms causing reduced reproductive success, impaired growth and development, and decreased survival.
Lichens, a group of non-vascular plants that accumulate such contaminants and are sensitive to airborne pollutants, can be used as indicators of urban pollution and point-source emissions like power plants. Elevated mercury concentrations have been found in lichens from the seashore at high elevation sites that intercept fog. Additionally, concentrations of arsenic and lead decrease with distance from south to north at the seashore, suggesting these two elements originate in the fine particulate haze that enters the park from San Francisco Bay Area (Bennett and Benson 2005).
Bennett, J. P. and Benson, S. 2005. Elemental content of lichens of the Point Reyes Peninsula, northern California. Sci Total Environ. 343 (1–3): 199–206.
Fenn, M. E., Haeuber, G. S., Tonnesen, J. S., Baron, J. S., Grossman-Clarke, S., Hope, D., Jaffe, D. A., Copeland, S., Geiser, L., Rueth, H. M., and Sickman, J. O. 2003. Nitrogen emissions, deposition and monitoring in the western United States. Bioscience 53: 391–403.
Kohut R.J. 2007. Ozone Risk Assessment for Vital Signs Monitoring Networks, Appalachian National Scenic Trail, and Natchez Trace National Scenic Trail. NPS/NRPC/ARD/NRTR—2007/001. National Park Service. Fort Collins, Colorado. Available at https://www.nps.gov/articles/ozone-risk-assessment.htm
Porter, E., Blett, T., Potter, D.U., Huber, C. 2005. Protecting resources on federal lands: Implications of critical loads for atmospheric deposition of nitrogen and sulfur. BioScience 55(7): 603–612. https://doi.org/10.1641/0006-3568(2005)055[0603:PROFLI]2.0.CO;2
Sullivan, T. J., McDonnell, T. C., McPherson, G. T., Mackey, S. D., Moore, D. 2011a. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: main report. Natural Resource Report NPS/NRPC/ARD/NRR—2011/313. National Park Service, Denver, Colorado. Available at https://www.nps.gov/articles/nitrogen-risk-assessment.htm
Sullivan, T. J., McDonnell, T. C., McPherson, G. T., Mackey, S. D., Moore, D. 2011b. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: San Francisco Bay Area Network (SFAN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/330. National Park Service, Denver, Colorado. Available at https://irma.nps.gov/DataStore/Reference/Profile/2168733.
Sullivan, T. J., McPherson, G. T., McDonnell, T. C., Mackey, S. D., Moore, D. 2011c. Evaluation of the sensitivity of inventory and monitoring national parks to acidification effects from atmospheric sulfur and nitrogen deposition: main report. Natural Resource Report NPS/NRPC/ARD/NRR—2011/349. National Park Service, Denver, Colorado. Available at https://www.nps.gov/articles/acidification-risk-assessment.htm
Sullivan, T. J., McPherson, G. T., McDonnell, T. C., Mackey, S. D., Moore, D. 2011d. Evaluation of the sensitivity of inventory and monitoring national parks to acidification effects from atmospheric sulfur and nitrogen deposition: San Francisco Bay Area Network (SFAN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/349. National Park Service, Denver, Colorado. Available at https://irma.nps.gov/DataStore/Reference/Profile/2170606.
Sullivan, T. J., Peterson, D. L., Blanchard, C. L. 2001. Assessment of Air Quality and Air Pollutant Impacts in Class I National Parks of California. National Park Service. 421 pp. Available at https://irma.nps.gov/DataStore/Reference/Profile/561620.
Sullivan T.J. 2016. Air quality related values (AQRVs) in national parks: Effects from ozone; visibility reducing particles; and atmospheric deposition of acids, nutrients and toxics. Natural Resource Report. NPS/NRSS/ARD/NRR—2016/1196. National Park Service. Fort Collins, Colorado. Available at https://www.nps.gov/articles/aqrv-assessment.htm.
Last updated: November 19, 2019