Ash from California Fires Potentially Problematic to Health, Environment
from last month's southern California fires may pose problems to health
and the environment, according to preliminary results from a U.S.
Geological Survey (USGS) study released to the Multi-Agency State and
Federal Task Force.
Samples collected from two residential areas burned by the Grass
Valley and Harris wildfires indicate that the ash contains caustic
alkali materials and can contain somewhat elevated levels of metals
such as arsenic, lead, zinc and copper. Ash from burned wildlands also
can contain caustic alkali materials, though at lower levels than the
residential ash, officials said on Dec. 4.
"These findings are consistent with the scientific knowledge about
wildfire ash that has led counties in California to issue advisories
regarding appropriate precautionary measures to avoid health problems
associated with exposure to the ash," said Dr. Geoffrey Plumlee, a USGS
lead author of the study.
Deborah Martin, a USGS wildfire ash specialist and study co-author,
stated: "The study results also indicate that rain-water runoff from
burned areas may adversely affect ecosystems and the quality of surface
drinking water supplies." Additionally, critical habitat for some
aquatic species may be affected by spikes in alkalinity as rainwater
mixes with ash to form surface runoff.
USGS scientists collected ash and soil samples from the two
residential areas as well as 26 other sites within areas burned by the
Harris, Witch, Ammo, Santiago, Canyon and Grass Valley fires. The
researchers wanted to help identify characteristics of the ash and
soils from both wildland and suburban burned areas that may adversely
affect water quality, human health, endangered species and debris-flow
or flooding hazards. These studies are part of the USGS Southern
California Multi-Hazards Demonstration Project. USGS researchers have
similarly studied samples from other disasters, including dusts from
the World Trade Center collapse and flood sediments from Hurricane
"The impartial scientific information produced by these studies can
be used by emergency response experts and decision makers to better
assess and respond to the environmental and health effects of disasters
such as wildfires, as well as to better anticipate and plan for effects
of future disasters," said Mark Myers, USGS director.
For more information, see "Open-File Report 2007-1407, Preliminary
Analytical Results for Ash and Burned Soils from the October 2007
Southern California Wildfires" at http://pubs.usgs.gov/of/2007/1407.