Air in Birmingham’s shisha bars is almost twice as polluted as smog-hit Beijing – and it is spilling out onto the streets, a shocking new report reveals.

The investigation into air quality inside 12 shisha bars across the city found dangerous levels of lethal carbon monoxide which is also linked to asthma, lung cancer and low birth rate

The research also showed the poor quality air was spilling out onto the streets – meaning people walking past bars are breathing in known carcinogens.

Researchers found four times the particle matter outside shisha bars than on the side of the busy Tyburn Road through north Birmingham.

There are 24 shisha bars operating in the city. In the first UK study of its kind, University of Birmingham researchers looked into carbon monoxide (CO) and other fine particles in the air and found:

* There was 43 times as much particulate matter in a shisha bar than on a busy arterial road.

* Carbon monoxide levels were 11 times greater than outdoor levels in Birmingham shisha bars, while there was eight times as much other particle matter.

* Air particle levels were 13 times higher in the shisha bars than pubs and restaurants, and with nine times the carbon monoxide.

* The air quality was also nearly twice as high as levels recorded in Beijing.

Researchers found visitors to shisha bars were breathing air far more polluted than the level recorded in pubs prior to the smoking ban introduced in England in 2007.

Since the ban was introduced, shisha bars have become more common and so far Birmingham City Council has prosecuted six shisha premises for failing to comply with smoke-free legislation. By 2014, the council had received 30 applications for shisha bars and investigated approximately 25 alleged unauthorised shisha premises.

Jacqui Kennedy, acting strategic director of place for the city council, said: “Our environmental health officers have noted the smoky atmosphere in shisha bars and restaurants whenever they had visited premises, which have to comply with smoke-free legislation.

“This study shows a worrying lack of awareness of the risks from premises and staff, as well as those who visit shisha bars.

“Given the success of the smoking ban, which has been in place for nearly a decade, compliance with the spirit of the smoke-free law is paramount in order to protect the health of non-smokers and staff, by reducing their exposure to second-hand smoke.”

Many customers and bar staff believed smoking shishas was safer than smoking cigarettes, as the smoke is “filtered through water”, they found.

They also found, on visits between March and June 2014, bar managers were unaware of the health risks.

A total of 75 per cent did not recognise the smoke from shisha pipes was a hazard to their customers or staff, nor the importance for smoking areas to be open to the air.

However, carbon monoxide and fine particulate matter can lead to oxygen depletion in haemoglobin in the blood, which can cause dizziness, shortness of breath, confusion through to loss of consciousness and death.