Britain's ongoing heatwave could result in children being sent home from school this week.
Teacher leaders are calling for the measures if classroom temperatures rise above 26°C. The mercury is expected to 35°C next week when many pupils will still be at school.
Schools are due to break up for the summer holidays within the next week, but in the meantime many children are not coping with hot and stuffy classrooms.
Union leaders have called for a maximum legal temperature limit of 26°C to be introduced, which would allow staff and children to be sent home.
If the hot weather continues until Tuesday, as expected, it will be the longest heatwave for 18 years, 17 days over 28°C.
