The risk fell to being twice as high as the national average once ethnicity and deprivation was factored out, but remained “statistically significant”.
A total of 88 London transport workers have died in the pandemic, 51 of them bus drivers. Many bus drivers are from BAME communities.
Friday’s report, the second from UCL Institute of Health Equity, finds that lives would have been saved if the first lockdown had started sooner than March 23 last year.
It says that all bus drivers need “continued protection” – on board and in bus depots.
Conservatives on the London Assembly described the report as a “whitewash” and said it ignored the “failure” of Mayor Sadiq Khan and Transport for London to keep drivers safe.
TfL said passengers would continue to be required to wear masks as lockdown lifted to help protect drivers.
TfL also agreed to immediately fit new ventilation devices to all 9,000 buses in the capital to improve the flow of fresh air to the driver’s cab.
The report, which analysed data from bus operators and the Office for National Statistics, said it “indicates around a three-fold excess in age-standardised mortality in London bus drivers, compared to the population of the country as a whole”.
It said that after taking into account ethnicity and deprivation, “London bus drivers had a statistically significant, two-fold excess in mortality in the first wave of the epidemic”.
The report analysed the first 27 London bus driver deaths, which happened between March and May last year. A further 15 occurred between June and January but the report authors said it was too early to draw “definitive conclusions”.
This week Mayor Sadiq Khan told the TfL board the number of bus driver deaths had risen to 51.
More than 18,500 Londoners have died in the pandemic.
The report said that 22 of the 27 drivers who died had stopped work by April 3, meaning their infection would likely have been contracted pre-lockdown.
UCL was asked by the Mayor and TfL to review the deaths. A first report was published in July.
Friday’s final report includes new data from bus operators and the Office for National Statistics to provide a better indication of the extent of excess mortality among London bus drivers in the first wave of the pandemic in London.
It says “some but not all” of the deaths were due to the higher proportion of BAME Londoners employed as the bus drivers.
A survey of bus drivers showed that rates of diabetes, hypertension and excess weight were “broadly similar” to the general population.
Professor Sir Michael Marmot, director, UCL Institute of Health Equity, said: “It is clear that an earlier introduction of the lockdown on 23 March 2020 would have saved lives.
“However, we do not know whether an earlier introduction of workplace preventative measures would have reduced Covid-19 infection and mortality in addition to the lockdown.
“We know pre-existing health conditions and ethnic composition play a role in Covid-19 infection and mortality.”
The report made a series of recommendations. These include “continued social distancing and mask wearing in all locations where bus drivers are out of their cabs”.
It said efforts were needed to reduce obesity in younger London bus drivers, and to prevent fatigue among drivers in general.
It said some drivers had reported an increase in “passenger aggression and non-compliance” and extra strains of the job caused by “new traffic measures”.
It added: “As breathing problems appear to be a pre-existing issue reported by many London bus drivers and are exacerbated in those self-reporting Covid-19, the Government and the Mayor of London should prioritise improving air quality on London’s roads.”
Mr Khan said: “We commissioned an independent review into the tragic deaths of bus drivers from coronavirus because we wanted to ensure we were doing everything possible to protect staff.
“As the son of a bus driver, this is deeply personal to me, and the transport workers who have lost their lives are constantly in my thoughts.
“The second part of UCL’s study makes clear that if the Government had announced a national lockdown earlier it would have saved drivers’ lives. We know that underlying health conditions and ethnicity were also contributory factors.
“We will continue to do everything we can to keep staff and passengers safe, and from this week we will be further improving air flow onboard by fitting a new part to windows to keep them permanently open.
“We will also be implementing the report’s recommendations in full. This will include working with bus operators to ensure staff receive the best possible support and improved wellbeing advice, ensuring enhanced sick pay continues to be made available for those who are ill or need to self-isolate, and taking tough action against people who refuse to wear face coverings.”
Keith Prince, GLA Conservative transport spokesman, said: “This report is a whitewash. It seemingly ignores the Mayor and Transport for London’s failure to keep bus drivers safe.
“In response to the first wave, the Mayor and TfL did not provide London’s transport workers with PPE, withdrew inspection staff from bus depots, and crammed drivers into busy canteens and ferry cars. They did not do everything they could to keep bus drivers safe.
“Khan needs to take responsibility and listen to their calls today for higher-grade protective equipment and proper enforcement of the mandatory face-covering rule.”
Tory mayoral candidate Shaun Bailey said: “The drivers’ deaths are a tragedy. What makes it worse is the thought that their deaths could have been prevented.
“The Mayor should have provided bus drivers with PPE from the start of this pandemic, just like drivers asked.”
Green assembly member Caroline Russell said: “I note how many of these drivers already had breathing problems, which the infection worsened – this raises the question of whether drivers’ exposure to polluted air at work contributed to their underlying poor health.”
Lilli Matson, TfL’s chief health, safety and environment officer, said: “We will work closely with the bus operators to ensure that those suffering or at risk from coronavirus will continue to receive support, with vulnerable drivers having to shield being able to stay at home, with sick pay for those with symptoms and access to a range of services.
“Further measures to improve ventilation on buses are being introduced, and we are working to drive a more proactive approach to drivers’ health and wellbeing.”