How hot is too hot to go to school?

The Elementary Teachers Federation of Ontario is calling on the province to develop an extreme heat protocol as teachers and students sweat it out in classduringthis week's record-setting heat.

The province has policies for extreme cold weather but not for extreme heat, despite the fact that classroom days in May, June and September three of ten teaching months have seen stifling temperatures.

"We've been encouraging the government to establish guidelines about what to do in extreme heat. It's really, really difficult to work in, clearly," said Craig Smith, president of the London local of ETFO, which represents teachers with the Thames Valley District School Board.

"It's hard for teachers and it's hard for students. Both working and learning conditions are linked. The conditions in which the kids are trying to learn are the same conditions in which our members are trying to teach and work," Smith said.

About 60 per cent of Thames Valley schools and 35 per cent of London District Catholic School Board schools don't have air conditioning.

That means in some schools, the morning temperatures are around 29 degrees and by the mid-afternoon can reach the mid-30s, Smith said.

Some parents have been keeping their children home from school to keep them out of the heat.

Whether to stay indoors all day or go outside is up to each school, said Lisa Munro, a learning supervisor at the Thames Valley board.

"We follow the heat advisories that are sent out by the board of health and we make judgement calls based on the school," she said.

Some schools might have more shade or wind, while others might be in full sun, she added.

"There are many factors to be considered. Keeping students safe is the high priority," Munro said.

The first step to keeping students safe is for parents to callthe Middlesex-LondonHealth Unit if their child is feeling unwell due to their school's heat. That's according to Jacqueline Kappers, a parent and former school council chair who has been pushing for cooler schools for the last four years.

The Middlesex-London Health Unit issued a heat alert four days ago.

Environment Canada has alsoissued a heat warning for the region on Tuesday, saying humidex values would approach 40 degrees.

A cold front is expected to move across southwestern Ontario on Wednesday, bringing cooler temperatures on Thursday.