The Department for Environment, Food and Rural Affairs insists the UK's air is safe after a landmark ruling that the Government is failing in it's legal duty to protect people from the harmful effects of pollution.
“Air quality has improved significantly in recent decades and almost all of the UK meets EU air quality limits for all pollutants.”
More top news
Official readings are recorded three metres in the air but a study found levels of nitrogen dioxide (NO2) were higher at pushchair level.
Tubes, trains, trams, buses, cable cars, river buses, taxis and going by foot - your guide to getting around during the strike.
Union officials rejected a revised offer from Underground managers during a meeting at the conciliation service ACAS this afternoon.