The safety body is now calling on employers and regulators to take these risks more seriously and has launched a campaign to raise awareness.

Lawrence Waterman, Chairman of the British Safety Council, said: “The Health and Safety Executive tells us that it doesn’t regulate the ambient environment, and the recent Clean Air Strategy had little or nothing to say about people who spend their working lives outdoors.

“These workers are caught in a blind spot and we think their health is at risk.”

The Time to Breath campaign will highlight every employer’s duty of care for the risks from ambient air pollution.

The BSC is backing the launch of the world’s first mobile app to measures road workers’ exposure to air pollution.

The new ‘Canairy’ app offers both advice on how workers can reduce their exposure and provides employers with intelligence to help protect their workforce.

Kier highways workers in London have trialled the app, which has been developed by London University’s King’s College and British Safety Council.

Mitesh Solanki, managing director for Kier Local Authority Highways, said: “At Kier, the health and wellbeing of our workforce is our number one priority and I’m really pleased that our LoHAC (London Highway Alliance) contract with TfL was the first to trial Canairy.

“This proactive approach to utilising the latest technology will help us reduce our people’s exposure to air pollution, which is a serious concern for all responsible employers.”

The app captures data from the London Air Quality Network pollution map and the worker’s GPS location to calculate exposure to pollution on an hourly basis.

Once this exposure exceeds World Health Organisation’s limits, the app notifies the user and suggests tips to reduce their exposure, including working away from traffic, reducing strenuous work or putting up a screen barrier.

Employers will be able to access this anonymised exposure data relating to their workers and use it to inform how they schedule work for them to avoid the worst levels of toxic air.

Waterman added: “We are calling on London-based employers to join those trialling Canairy and help us build an accurate picture of the exposure faced by outdoor workers.

“This information will be a cornerstone of future campaigns for better research into the links between occupation and health data.

“Given that we don’t even know how many outdoor workers there are in the UK, we need those authorities with responsibility for our health and environment to work together on this issue.”