Harris County will spray 63,000 acres in the northwest portion of the county by air to combat West Nile virus.
The spraying has been scheduled for Wednesday evening, unless it rains.
Officials with thee Harris County Public Health and Environmental Services' Mosquito Control division said West Nile virus activity has recently increased. It has been confirmed in more than 300 mosquito samples and nearly 100 dead birds, officials said.
"Harris County is experiencing an increase of West Nile Virus infection in mosquitoes and, most notably, in the dead bird population," Dr. Rudy Bueno said. "This situation has prompted the need to supplement the ongoing countywide ground treatment with aerial treatment in the designated areas to better protect the health of our residents."
The county has reported six human cases of West Nile virus this year. There have been 13 human cases in the city of Houston, and three of those cases was fatal. There have been more than 20 West Nile virus-related deaths in Texas in 2012.
The insecticide that will be sprayed is Dibrom, which has been approved by the Environmental Protection Agency. It's considered to be safe for the environment and is routinely used to combat mosquito-borne disease.
"Because of the very small amount of active ingredient released per acre of ground, the estimates found that for all scenarios considered, exposures were hundreds or even thousands of times below an amount that might pose a health concern," an EPA representative said.
Officials recommended that people stay indoors while their area is being treated, as a precaution.
Authorities also recommend that people take personal measures to avoid being bitten by mosquitoes. It is recommended that people use an insect repellent containing DEET, Picaridin, oil of lemon eucalyptus or IR3535 as an active ingredient. Wearing long-sleeved shirts and long pants at dawn and dusk, when mosquitoes are most active, is encouraged.