PROVIDENCE — The state departments of Environmental Management and Health have announced that aerial mosquito treatments would start at dusk on Sunday, Sept. 8, weather permitting, with the possibility of a second night of spraying if needed.
All spraying will occur in the evening and overnight hours. The application will treat four areas that the state Mosquito-Borne Disease Advisory Group has assessed to be at critical risk for the Eastern Equine Encephalitis virus.
Critical risk areas include communities in northern Rhode Island bordering the Massachusetts border; Central Falls; parts of Westerly, and West Warwick. On Thursday, the state conducted “larviciding” flights, in which a helicopter dispersed pellets of pesticide to kill mosquito larvae in swampy areas near Central Falls, in West Warwick, and in the Chapman Swamp area of Westerly.
A map of the spraying areas also includes Ashaway and a slice of the western border of Charlestown.
There has been one human case of EEE in Rhode Island this year and one horse tested positive. Generally, spraying will occur in 4-mile radiuses around positive samples or cases. Because the aim of spraying is to protect humans from EEE infection, some areas will be excluded, including open bodies of water (including drinking water reservoirs), certain coastal areas, and natural areas that are not densely populated. Organic farms will also be excluded.
The ability to spray depends on the weather. With the remnants of Hurricane Dorian tracking northward, the schedule may change. Calm conditions are needed to conduct aerial spraying.
The product used in this application is called Anvil 10+10. It has been used extensively in both ground-level and aerial spraying and has proved to be extremely effective in killing mosquitoes worldwide for more than 20 years, officials said.
Anvil is registered by the federal Environmental Protection Agency and in Rhode Island and Massachusetts for this use. The product is being used at very low concentrations. No adverse health risks are expected with its use for mosquito control. However, if people want to limit their exposure to this pesticide, they can avoid being outdoors while spraying is occurring and can keep their windows closed.
Officials said that the state has contracted with Dynamic Aviation to conduct the spraying. The company uses a King Air Beechcraft fixed-wing, dual-engine plane equipped with nozzles on the wings that disperse an ultra-low volume droplet, precisely configured to match the size of the adult mosquito, which is only a few microns long.
The product is applied at low dosage rates using specialized equipment that automatically adjusts for aircraft speed, altitude, and wind speed.