Kensington and Chelsea has the most polluted air in the United Kingdom, with more than one in 12 of all deaths in the London borough attributable to tiny particles of soot largely emitted by diesel engines. The only other borough with similar pollution levels is nearby Westminster.

The statistics, collated by locality for the first time by Public Health England – an agency of the Department of Health – suggest that London and south-east England have by far the worst air in Britain, largely due to traffic levels. In London, 3,389 people died of air pollution and 41,404 "life years" were lost in 2010, while in south-east England, 4,034 people died and 41,728 years were lost.

The study confirms that the purest air in Britain is to be found in Scotland and places where there are few cars and the prevailing wind blows off the Atlantic. Only eight deaths in the Outer Hebrides, six in the Orkneys and six in the Shetland Islands were attributable to air pollution. Moyle was the cleanest borough in Northern Ireland and Gwynedd in Wales. Cumbria, Northumberland and Cornwall were the regions that had the lowest percentage of deaths from air pollution in England.

In total, said the study, based on the work of the Committee on the Medical Effects of Air Pollutants, estimated that long-term exposure to air pollution causes 28,869 deaths a year and 306,835 life years to be lost. Air pollution is now officially the biggest public health risk after smoking.

The figures were calculated by modelling annual average concentrations of minute man-made particles of less than 2.5 microns in diameter, known as PM2.5, and their impacts on health. These minuscule particles, emitted largely by diesel engines, reduce visibility and cause the air to appear hazy when levels are raised. Because they are so small, they can travel deep into the lungs and cross into the bloodstream, causing heart and lung disease, cancer, and aggravating asthma.

The estimates are made only for long-term exposure to particulate air pollution rather than short-term exposure to high pollution episodes such as those experienced last week across southern Britain, when dust from the Sahara mixed with local air pollution. Because this is the first time that the figures have been calculated on a borough-by-borough basis, it is not possible to compare them with other years.

A woman walks through smog in Kensington Gardens, April 2014. Photograph: Suzanne Plunkett/Reuters

Britain, with a few exceptions in London, is within the EU legal limit for particulate pollution but is being taken to court by the European commission for consistently missing targets for another air pollutant, NO2. This mixes with particles and other chemicals in the air to further aggravate health risks. Diesel fumes are known to be more damaging to health than those from petrol engines.

A 2011 study showed that diesel-related health problems cost the NHS more than 10 times as much as comparable problems caused by petrol fumes. Last year the UN's World Health Organisation declared that diesel exhaust caused cancer and was comparable in its effects to secondary cigarette smoking.

"Current levels of particulate air pollution in the UK have a significant impact on the life expectancy of the population. In the UK, a 15% reduction is required by 2020," said the report.

Environment groups called on government to tackle the cause of air pollution deaths. "It's outrageous that tens of thousands of people die because of polluted air. Ending this national disgrace should be a top priority for politicians. Ministers and local authorities must develop an urgent action plan to introduce cleaner vehicles and encourage the use of alternative forms of transport – people won't be able to breathe easily until they do," said a spokeswoman for Friends of the Earth.