Southern California and California's Central Valley are among the most heavily polluted areas in North America. Ozone, acidic gases and particulates are transported long distances to forests of the central and southern Sierra Nevada and the transverse mountain ranges of southern California. Although pollution control devices required in the state of California on both industrial and mobile sources have significantly reduced the number of days that exceed state and federal ozone standards, overall pollutant exposures are high and are expected to increase.
Our goal is to provide high quality scientific information that will provide a scientific basis to set protective air quality standards, and to provide estimates of future changes in forest ecosystems.
Emerging Research Needs
Critical Load: the concentration of air pollution [loading rate, e.g., kg/ha/yr] above which a specific deleterious effect may occur. A critical load or concern threshold value should:
- protect the most sensitive AQRVs (Air Quality Related Values);
- be based on the best science available;
- ensure that no unacceptable change occurs to the resource.
Major Research Initiatives:
Air Pollution and Global Change:
We need a basic understanding of tree response to atmospheric pollutants and drought stress.
Monitoring of air pollution concentrations, deposition, and effects is needed to determine the extent and magnitude of pollutant deposition in areas at risk and determine forest stand structure and composition response.
Smoke Effects / Smoke Emissions:
Management of visibility/regional haze is an important issue facing the Forest Service, especially in Class 1 Wilderness areas. Scientists in PSW are involved in these issues from a smoke management and smoke chemistry perspective, as well as, the impacts of industrial development and urbanization.
Prescribed fire is an important management tool for National Forest managers.
There is a critical need to determine whether prescribed burns comply with
local and regional air quality regulations, and if not, what conditions
lead to non-compliance. Existing models of smoke chemistry, transport and
dispersion need to be tested under local and regional conditions. Ground
based, low-cost monitoring equipment for measuring smoke emissions has been
developed and will be tested to quantify the location, chemistry, concentration,
and deposition of air pollutants from prescribed and wildland fire.