As the annual mosquito spraying season kicks off in Birmingham, some concerned residents and the Greater-Birmingham Alliance to Stop Pollution (GASP) say they worry about what exactly is being sprayed.

City officials say the spray targets mosquitos, but GASP and others cited concerns about other possible environmental impacts.

“The people of Birmingham need more transparency from the city about what sprays they are using,” said Michael Hansen, executive director of GASP.

Like many cities, the Birmingham Department of Public Works sends trucks out weekly to spray for the common hot weather pest. Birmingham sprays all 99 city neighborhoods between mid-April and October of each year according to Rick Journey, director of communications for the city.

These trucks spray “an ultra-low volume (mist) of product formulated to work with a mosquito’s biology” according to the city’s mosquito control website. Less than a tablespoon of this “product” is used over an entire acre, the website adds.