In the Southeast, Who’s in the Path of Smoke Plumes?
Social vulnerability and smoke dispersion from wildfires and prescribed burns
For more than 30 years, researchers have known that poor communities and people of color in the U.S. are more likely to be affected by environmental threats such as landfills and toxic waste sites. “Are these socially vulnerable communities also exposed to more smoke from wildfires and prescribed fires?” says U.S. Forest Service scientist Cassandra Johnson Gaither. Very few studies have examined the relationship between social vulnerability and exposure to wildfires or prescribed fires.
Compared to other parts of the country, the southern U.S. has the highest number of wildfires per year. Through the years from 2003 to 2013, there were over 800,000 wildfires in the country. Over 375,000 of those were in the Southeast. “These figures are particularly compelling given that the southern states account for only about a quarter of the total national land area,” says Johnson Gaither. The Southeast also has the most forest land burned in prescribed fires each year.
Smoke from wildfires and prescribed fires can irritate the eyes, nose, and throat and worsen existing respiratory illnesses. People in the Southeast are especially susceptible to these effects because of the relatively high amount of smoke produced, the high numbers of people living in the wildland urban interface, and because air masses that trap smoke near the ground are common.
Johnson Gaither, a research social scientist at the SRS Integrating Human and Natural Systems unit, and Scott Goodrick, a research meteorologist at the SRS Center for Forest Disturbance Science, examined the relationship between social vulnerability – which includes ethnicity and race, economic status, age, and other variables – and the number of smoke plumes across the 13 southern states. The scientists also looked at how close hot spot communities – those that are above average in terms of social vulnerability and plume exposure – were to national forests in the South. The study was recently published in the journal Forests.
Johnson Gaither and her colleagues studied five ecoregions of the south in both winter, when prescribed fires are more likely to be conducted, and in spring/summer, when wildfires are more common. The scientists found that hot spots tended to shift seasonally. For example, in the Appalachian Cumberland ecoregion, winter hot spots were clustered in northern Alabama and east central Tennessee. However, in the summer, the hot spots shifted to the extreme western edge of the ecoregion in central Tennessee. Hot spots also tended to be associated with national forests. In the Coastal Plain, areas near the Francis Marion National Forest, South Carolina, were hot spots in both winter and spring/summer.
When the average number of smoke plumes across all communities was considered, scientists found that socially vulnerable communities were exposed to similar numbers of smoke plumes as other areas. “However, we also looked at exposure per person,” says Johnson Gaither. “In four of the five ecoregions studied, communities with high social vulnerability were subject to more smoke plumes per person than other communities.”
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For more information, email Cassandra Johnson Gaither at cjohnson09@fs.fed.us.