Aerial sprays for mosquitoes will cover about 600,00 acres of Harris County.
Aerial sprays for mosquitoes will cover about 600,00 acres of Harris County.
Map courtesy of Harris County Public Health

With Mosquito Threat Growing, Harris County Begins Aerial Sprays

With standing water and piles of debris from Hurricane Harvey creating breeding grounds for mosquitoes, the Harris County Public Health Department has authorized the aerial spraying of Dibrom, an EPA-approved pesticide, over 600,000 acres of the county starting Thursday.

“About 10 to 14 days after a flood like this, you’re going to have an increase in mosquito activity,” said Dr. Umair A. Shah, the executive director of the public health department, in an interview with the Houston Press on Tuesday. “We’re already seeing it.”

The county has been “aggressively ground spraying” for mosquitoes since last week, Shah said, but with the increased risk of mosquitoes, has authorized C-130 cargo planes from the U.S. Air Force Reserve’s 910th Airlift Wing in San Antonio to drop Dibrom along Harris County’s north and southern borders.

Dibrom is the trade name of a chemical called Naled, which has been approved by the EPA since 1959 and has been used by the Centers for Disease Control and Prevention after floods and hurricanes in the past. The insecticide caused some nervousness, though, in the United States after the European Union banned the substance in 2012, citing unhealthy side effects on aquatic life and humans who inhale the chemical or come into direct contact with it.

But the CDC has said Naled is only dangerous in concentrations much higher than licensed professionals use during sprays. A 2008 study from the American Mosquito Control Association found that residents who lived in an area that was aerially sprayed did not have higher levels of Naled in their system after sprays.

Naled, though, has been reported to kill bees so beekeepers in affected areas should cover hives before spraying begins Thursday.

Harris County’s health agency said residents concerned about the spray should stay indoors during the flyovers, which could last several days.

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