Councillor Jonathan Cook has expressed “frustration and disappointment” that a pollution monitoring scheme Mayor Sadiq Khan has just launched at hospitals across London does not include St George’s.

The mayor said his scheme would provide information that could help vulnerable patients avoid unnecessary exposure to pollutants.

But almost all the ten hospitals identified in the scheme are less busy than St George’s and most treat fewer accident and emergency patients each year.

Mr Cook, the council’s transport and air quality spokesman, said: “It defies logic that such a busy hospital as St George’s has not been included in the mayor’s plans.

“Given its location next to the busy A24 and its proximity to a large number of bus routes, many of which sit idling outside the entrance day after day, it really beggars belief that it’s not part of this initiative."

The council said that pollution levels at St George’s are also impacted by having bus routes terminate at the hospital with many left idling whilst their drivers await return journeys.

St George’s is served by 11 bus routes – including four that operate directly outside the hospital entrance in Blackshaw Road, and one – the 493 - that travels through its grounds.

“Without the hard data this study could produce about local pollution levels in this part of Tooting it will be harder to persuade the Mayor to invest in measures to tackle the problem or help NHS staff give patients and visitors advice and information on how to stay safe," Mr Cook added.

“We believe the Mayor should have a simple rethink and expand his scheme to make sure St George’s is included.”

The hospital's A&E department is one of the country’s busiest with around 173,000 patients treated there each year.

In contrast, the mayor has chosen to install monitors at Whipps Cross Hospital with 153,000 A&E patients, Newham with 141,000, St Thomas’s with 150,000 and the Royal London with 155,000.

According to the mayor’s press statement “the new hospital monitors will support the NHS by providing real-time air quality measurements that will allow health professionals to take appropriate action to protect patients and employees – for example, warning patients about high pollution episodes and advising which hospital entrances have the lowest levels of pollution.”