Many schools in B.C. are aware of the increasing number of children allergic to peanuts and have made classrooms peanut-free. (CBC)

Heading back to school can be stressful for families, but for parents who have children with allergies, it can be a matter of life and death.

"He could die. I mean, that is the worst case scenario," Marnie Miller said Tuesday of her son's allergies to peanuts and tree nuts.

Miller and her husband, Craig, had already discussed their concerns with Grade 1 teacher Beth Kondra at Laronde Elementary School in the Vancouver suburb of Surrey several days before their son, Luke, went to school Tuesday.

Kondra said two students in her class last year carried a device that gave automated doses of epinephrine to calm down allergic reactions, and she expects more students will have similar issues with allergies this year.

Marnie and Craig Miller say they are concerned about their son, Luke, who's allergic to peanuts and tree nuts, heading back to school Tuesday. (CBC)

"You are always thinking every day, 'What did somebody bring or shouldn't have brought in their backpack or what has somebody touched or not touched?" Kondra said.

Leah La Rocque, 7, is allergic to a long list of things such as nuts, dairy, shellfish, coconut oil and dog saliva. A special classroom has been set up for the Grade 2 student at James Whiteside Elementary School in the Vancouver suburb of Richmond.

"This is what I would call the bubble classroom — the safety zone," said Gail La Rocque, Leah's mother.

No food is allowed in La Rocque's classroom. The carpets have been replaced by linoleum. Other students have to wash their hands first thing in the morning and take off their shoes in class.

Dr. Edmund Chan, an allergist with the B.C. Children's Hospital, says the western lifestyle is one of the factors contributing to the rising number of allergies in people. (CBC)

"We do not make it an allergy-free environment," said Carolyn Sakata, principal of James Whiteside school.

"We want Leah to learn what she needs to do and we want people around her to know and to be sensitive to someone who's highly allergic. But there's no denying it can be very stressful," she said.

An allergy expert at the B.C. Children's Hospital in Vancouver said there has been an increase in cases of young children showing allergic reactions to various food groups in the past 10 years.

"The cause is a complex interaction between genetics and the environment, " Dr. Edmund Chan said. "It appears that the western lifestyle in developed countries is playing a huge role."

"The hygiene hypothesis tends to describes the rise in allergies secondary to fewer exposures to germs and infectious agents. That could explain why there's more allergies in developed countries like Canada versus developing countries," he said.

The number of children allergic to peanuts has increased from less than one per cent to 1.5 per cent over the last 10 years, Chan said.