Living in the UK's most polluted cities and towns increases the risk of an early death by the equivalent of smoking 150 cigarettes a year, a charity has warned.
The British Heart Foundation's analysis shows that people living in areas such as Portsmouth, Dartford, Medway, Gravesham and Thurrock are badly affected.
It said air pollution must be declared "a public health emergency".
The BHF wants the next government to urgently introduce tougher World Health Organisation (WHO) air pollution limits. It said current EU limits - which the UK comfortably meets - for fine particulate matter (PM2.5) are 25 micrograms per metre cubed as an annual average. The WHO limits are tougher - at 10 micrograms per metre cubed as an annual average.
The BHF said PM2.5 can have a "seriously detrimental effect to heart health", increasing the risk of heart attack and stroke and making existing health problems worse. It says that around 11,000 coronary heart disease and stroke deaths each year in the UK are caused by particulate matter air pollution.