Babies in prams are twice as likely to be exposed to harmful air pollution during the morning school run than in the afternoon, a new study has found.

The University of Surrey research, which was published in the journal Environmental Pollution, looked at the levels air pollution babies and toddlers are exposed to when they accompany older siblings on the journey to and from school.

Researchers carried out experiments using air monitoring equipment placed inside a pram to gauge the kind of pollutants and toxic chemicals young children encounter during an average day.

The study found that there were more small-sized pollution particles in the air during the morning school run than in the afternoon. It also revealed the worst places for babies to be exposed to pollution are at bus stops and traffic lights as they wait to cross roads.

A recent WHO report claimed that every year 570 000 children under 5 years die from respiratory infections, such as pneumonia, which can be attributed to indoor and outdoor air pollution, and second-hand smoke.

As a result of the study, the researchers are advising parents to use pram covers to help protect their babies from potentially harmful exhaust emissions.

Dr Prashant Kumar, lead author and Reader at the University of Surrey, said: “Previous research has shown that young children are far more susceptible to pollution than adults, due to their immature and developing systems and lower body weight.

“Essentially, children could be at risk of breathing in some nasty and harmful chemical species such as iron, aluminium and silica that form together the particles of various size ranges.

“One of the simplest ways to combat this is to use a barrier between the in-pram children and the exhaust emissions, especially at pollution hotspots such as traffic intersections, so parents could use pram covers if at all possible.”