'I was horrified that children are breathing air this dirty inside the school'

Head of Holborn primary school shocked to learn air pollution in classrooms far exceeds World Health Organisation guidelines

• Children inhaling toxic air on school run and in classroom

Headteacher Gwen Lee had not expected the results to be good but had been unprepared for what the air pollution engineer found.

Levels of dangerous particulate pollution exceeded WHO guidelines in every classroom of the school - and two were more than three times over the limit.