If the case against Greenwich Council is successful, it could compel local authorities in smog-ridden cities to put the health of residents before the convenience of the motorist. It is likely to come to court in the next month.
Parents had applied to the council for Trafalgar Road to be diverted after noticing their children's health deteriorated when hot, still weather caused serious pollution.
According to the children's solicitors, Leigh Day and Co, Greenwich's location in a valley means airborne pollutants are trapped at ground level, leading to severe outbreaks of respiratory problems among children.
The council considered closing the road at a meeting at the end of June, and decided it had no power to divert traffic.
The families have been granted legal aid to get a High Court judge to review that decision on the grounds that the council does have such power.
The solicitors cite correspondence between the Department of Transport and Oxford City Council in 1994 which they say confirms that the council does have power to close roads for environmental reasons under the 1984 Road Traffic Regulations Act.
The effects of the traffic are so bad that helpers at the nearby Meridian primary school have been trained in how to deal with children with respiratory problems because the teachers alone cannot cope.
At the school, 40 yards off the road, the drone of the traffic as well as the exhaust fumes invades the classrooms. Twenty of the school's 200 children use inhalers - well above the average.
Pauline Gebbett, whose 12-year-old son James has asthma, described the choking congestion on the road during the rush hour as similar to that found in the nearby Blackwall Tunnel under the river Thames. "You would not drive through with your window open, would you?" she asked. "But for us there is no escape."Reuse content