According to World Health Organization guidance, every outer London borough exceeds the safe limit for harmful gases and particles (nitrogen dioxide and particulate matter).
The 5 boroughs with the highest rate of emergency adult asthma hospital admissions in 2018-19 were all in outer London. More than 500,000 people in London have asthma, with over half of these people living in outer London.
The greatest number of premature deaths attributable to air pollution are in outer London boroughs, due to the higher proportion of elderly Londoners in these boroughs who are more vulnerable to the negative health impacts.