Spraying for mosquitoes began in Boston's West Roxbury and Hyde Park neighborhoods Monday evening.
With concern growing across Massachusetts after two men were diagnosed with the Eastern Equine Encephalitis virus, city crews were spraying in the two neighborhoods from dusk until 11:30 p.m. using a truck-mounted aerosol sprayer.
The health commission says the formula used contains pesticide and sumithrin to control the mosquitoes. They say people should minimize their exposure. If you see the truck, officials want you to go inside for a couple of minutes as the spray dissipates. They also encourage you to close windows during and after the spraying.
Sumithrin is classified as slightly toxic by the Environmental Protection Agency.
The health commission says it does not pose a significant risk to people and pets due to low toxicity and the small amount used to control mosquitoes.
While aerial spraying reduces the risk for EEE, health officials are reminding residents it doesn't eliminate it completely. Residents are still reminded to use insect repellent and to wear long sleeve shirts and pants to avoid getting bitten by mosquitoes.
Although rare, EEE is a serious and potentially fatally virus. Symptoms can include fever, headache, stiff neck and sore throat.
Laboratory testing confirmed the potentially deadly virus in a Grafton man who is between the ages of 19 and 30 and a Rochester man who is older than 60, the state's Department of Public Health said.
In addition to the two human cases, a young goat in Bristol County also tested positive for EEE this year, health officials said.
To learn more about how to protect yourself from the illness, visit mass.gov/dph/mosquito or call the DPH Epidemiology Program at 617-983-6800.
