Unreliable car emissions tests harming fight against air pollution, expert says

On the road and lab test discrepancies undermining efforts to curb toxic air levels as UN environment assembly admits global response is not up to scratch

The growing gulf between laboratory tests and real world air pollution from cars is hampering efforts to cut the toxic air that kills millions of people a year worldwide, a leading expert has warned.

The UN admitted on Tuesday that the global response to air pollution is not up to scratch, after it was revealed last week by the World Health Organisation (WHO) that harmful airborne particulates had risen by 8% in cities around the world.