The schemes — which ban parents from dropping off or collecting children by car — have proliferated across the capital since the start of the pandemic. Enforcement cameras can result in £130 fines.
But only about one in four have been introduced in areas where there is the greatest need to tackle toxic vehicle emissions, according to Westminster university.
The research said: “Just 13 per cent of schools that have the poorest air quality have school streets. The school streets policy is not effectively reaching schools where children are likely to be most exposed to air pollution from motor vehicles.”
More than 500 school streets are now in place across London. City Hall estimates that they reduce nitrogen dioxide by up to 23 per cent during morning drop-off. A quarter of rush-hour traffic is blamed on the “school run”.
Boroughs such as Hackney (39) and Lewisham (33) have introduced most school streets but there are none in Bexley or Hammersmith and Fulham, according to the research.
The schemes are seen as useful in reducing road danger and encouraging children to walk, scoot or cycle to school.
About 27 per cent of state-funded primaries and six per cent of state secondaries in London have school streets. But the researchers said new schemes should be better targeted at areas in the greatest need.
Lead researcher Asa Thomas said school streets had grown in a “patchwork” manner because they were delivered by the boroughs. “If you live in Hackney they are probably fairly distributed but if you live in another part of the city you are very unlikely to enjoy the same equity of benefits,” he said.
“Part of this inequity might be down to the fact they tend to be implemented in quite residential streets. If we are going to prioritise active travel and road safety, then we also need to develop the tools to deliver these interventions in schools on main roads as well.”
The research did not assess whether school streets were more likely to be introduced by Labour or Conservative boroughs. But a third of schools in inner London - where boroughs are more likely to be Labour - have school streets, compared with 18 per cent in the suburbs, which tend to be Tory authorities.
Mr Thomas said they were “much less politically contentious” than low traffic neighbourhoods (LTNs), which restrict traffic over a much larger area and normally throughout the day.
“The boroughs that have done most with school streets have tended to be inner city Labour boroughs,” he said. “But in contrast with other interventions, such as LTNs, there has been more enthusiasm in outer London boroughs for school streets.”