North Kent has been named one of the biggest offenders for levels of toxic air.
Dartford, Gravesham and Medway were among the worst affected areas for pollution with an increased risk of death equivalent to smoking more than 140 cigarettes a year.
The figures are based on levels of fine particulate matter called PM2.5 and have been released by Public Health England.
It revealed Dartford had the second highest average daily level of air pollution of all local authorities in the south east of England.
That's the equivalent of smoking 144 cigarettes a year.
This was followed by Medway (142) and Gravesham (139), which were the fourth and fifth worst offenders respectively.
The British Heart Foundation has branded air pollution "a public health emergency".
Research commissioned by the charity has shown PM2.5 can have a detrimental effect to heart health, exacerbating existing conditions and increasing the risk of heart attacks and strokes.
Before Parliament was dissolved the government introduced the Environment Bill, which set out a commitment to binding targets for fine particulate matter.
This fell short of adopting World Health Organization (WHO) guideline limits which stand at 10 micrograms per cubic meter of air.
Current EU limits - which the UK consistently meets - are 25 micrograms.
The BHF has urged the next government to urgently adopt into law the tougher WHO air pollution limits.
Dartford mum Mandy Garford set up the Dartford Clean Air project after her newborn baby was left on life support following a severe respiratory infection.
She said parents have contacted her to voice their concerns on how pollution affects their families.
"Some Dartford residents have been so concerned they have moved away," she said.
The teacher, 42, from Stone, added: "All groups involved understand that there are many contributing factors to our current air pollution levels and many different ideas, solutions and approaches may be needed.
"This is why we feel it is important to have the input of a number of different groups with a variety of concerns and consequently many different ideas to help.
"This is an issue that affects us all and knows no boundaries. It’s time that this was taken seriously.
"We need investment, creative, out-of-the-box, joined up thinking and strong policies from the local council, Kent County Council and the government to protect us."
Residents living close to one of the worst hit areas, the Dartford Crossing, have called for intervention and tougher action.
One of the homeowners in Brent Way said on bad days she can "smell and taste the vehicle fumes".
Ann Langdon said since moving to Dartford with her family in 2005 the traffic near the M25 has only got worse.
"We need interventions which increase the distance pollution must travel from vehicles to our homes," she said.
"The council tell us to use our cars less but our bus service is most likely going to be cut.
"My children are the human guinea pigs. A scientific experiment on the impact of a growing child’s lungs."