There are "clear inadequacies" in pollution safeguards imposed on the planned expansion of Heathrow Airport, London Assembly members have said.
Measures against the impact of a third runway were not "fit for purpose", its environment committee added.
It was also concerned that no single authority would ensure owners BAA and airlines complied with pollution rules.
London Assembly committee chairman Murad Qureshi said: "Our investigation has raised grave concerns about some of these safeguards, including clear inadequacies in approaches to tackling air pollution levels around Heathrow.
"We would also question whether the suggested noise benchmark is fit for purpose and if the aviation emissions targets are achievable." read more