Dangerously high levels of nitrogen dioxide have been found at two-thirds of English airports. The Chartered Society of Physiotherapy said EU limits for the noxious gas were breached at 16 out of 23 airports. Readings at Birmingham, Newcastle, Heathrow and Gatwick airports exceeded the recommended maximum of 40 micrograms per cubic metre by up to 75%. While aircraft contributed, motor traffic to and from the airports was the dominant pollution source. Birmingham’s operators said readings near the M42 were misleading. At least 90% of its traffic passed the airport by.