BOSTON (CBS) – Health officials are spraying to kill mosquitoes in Boston as concerns over EEE continue to grow. The spraying lasted for about three and a half hours and hit parts of Hyde Park and West Roxbury.

A pickup truck mounted with special equipment went up and down select streets and sprayed a pesticide.

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The Boston Health Department says if you see the truck coming it’s a good idea to head inside and wait a few minutes for the spray to disappear.

Brian Farless of the Suffolk County Mosquito Control Project says they spray areas with high mosquito populations.

“The sprayer puts out a fine mist into the air and then it kills mosquitoes that are present, that are presently flying,” Farless said. “It touches the mosquito and kills the mosquito. Then the product lands minutes after and it leaves no residual.”

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Mosquito Control spraying in Boston (WBZ-TV)

“This is routine for us,” Farless said. “We trap weekly throughout the season, and as we find high populations that’s when we determine to spray.”

Farless said the spraying is not a result of the two recent human cases of EEE in the state. EEE has not been found this year in Boston.

“It is rare to find EEE in the city, it has happened before and it could happen again but it is rare,” Farless said.

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Spraying will continue Tuesday in East Boston.