The spraying comes after recent tests found mosquitos carrying the West Nile Virus.
"Which we normally see, historically, around this time of the year in various parts of the county."
That's Dr. Rudy Bueno, the director of Mosquito Control for Harris County Public Health and Environmental Services.
"And so when we start to see that cluster of activity in mosquitos, we'll take pro-active measures and knock out those mosquito populations and lessen the exposure to people."
Tomorrow night around dusk, aerial spraying will begin over an area that's bounded by Gessner on the east, Highway 6 on the west, Highway 290 on the north, and Bissonet to the south. The county is using Dibrom. It's an EPA-approved insecticide that's considered safe for the environment. But Dr. Bueno says some people in the area could be sensitive to it.
"So we just ask them to stay from direct contact with the chemical. Just stay inside."
The spraying operation is expected to last until about 4 o'clock Thursday morning. So far this year, there have been two reported human cases of West Nile in Harris County. They were in the north and northwestern parts, and those areas have already been sprayed. Dr. Bueno says people can reduce their risk by wearing mosquito repellent, particularly at night, and by getting rid of any standing water around their homes.