GARDINER – Barry Freeman cleaned a section of the graphic design classroom at Gardiner Area High School with a commercial scrubber using no water or chemicals.

Freeman was one of the demonstrators at a “green” custodial conference held at the school Thursday.

Jon Stonier, director of operations for Regional School Unit 12, said 360 custodians, housekeepers and maintenance workers from schools and businesses around the state attended the event, sponsored by Clean-O-Rama, a cleaning supply company from Gorham.

Stonier said this year’s convention was the largest ever. The event has grown over the last 10 years from 120 to 360 participants.

Among 13 classes held for custodians Thursday were seminars on blood-borne pathogen safety, carpet care made easy, and routine machine care.

Stonier said people are taking advantage of the free training, and learning about chemical-free equipment.

“The push is to try and clean the buildings in a greener way, to reduce the amount of chemicals going into the environment,” Stonier said. “There’s machines that clean the floors with water and a pad. With all the budget cuts, this is a way to save money. An average-sized school can easily spend between $3,000 and $4,000 to strip floors. It’s also safer for staff and safer for students.”

More states are requiring maintenance staffs in schools and government buildings to use cleaning products that are less toxic than those used in the past.

According to the Green Schools Initiative, a nonprofit that works to improve the health and sustainability of the school environment, cleaning products that typically are used in schools contain carcinogens, reproductive toxins, neurotoxins, and chemicals that cause asthma.

Custodians and teachers suffer from asthma at much higher rates than the general working population, according to the National Institute for Occupational Safety and Health. The rates are attributed in part to exposure to cleaning products.

The Maine Department of Education initiated a “Green Cleaning Program for Schools” to address chemicals used in schools.

The program encourages the use of chemicals for cleaning public schools that do not harm workers or children and promote the implementation of green cleaning programs.

Paul Caron, director of facilities for the Brunswick School Department, had 37 of his employees take the classes Thursday.

He said his No. 1 priority at the event is the training, but his staff also benefits from networking with people from other school departments.

“We get ideas and then go back and ask for more money for equipment for those new ideas,” Caron said. “Any money we save from using less chemicals is reinvested back into education.”

The conference also drew participants from Sanford, Yarmouth and South Portland, and school and city officials from Portland.