Air pollution in the UK is worse than first thought and is responsible for 40,000 deaths a year, according to a report out today by the Royal College of Physicians.

The report, also compiled by the Royal College of Paediatrics and Child Health has calculated that 40,000 people in Britain die early because of outdoor air pollution, an increase on the previous estimate of 29,000.

Unborn and young children are particularly susceptible to air pollution, according to the study.

Dr Andrew Goddard, of the Royal College of Physicians, said: "Taking action to tackle air pollution in the UK will reduce the pain and suffering for many people with long-term chronic health conditions, not to mention lessening the long-term demands on the NHS."

Levels of air pollution, most of it caused by vehicles, are above legal limits in 25 cities including Oxford.

Pollution levels have fallen since a city council team started monitoring in 1995 – from about 65ug/m3 (micrograms per cubic metre of air) to about 52ug/m3 – but that they are still above the national objective of 40ug/m3, which needs to be met by 2020.

In Wallingford, environmental group Sustainable Wallingford has called for new measures to tackle air pollution around Wallingford Bridge.

The introduction to the report said: "Each year in the UK, around 40,000 deaths are attributable to exposure to outdoor air pollution which plays a role in many of the major health challenges of our day "It has been linked to cancer, asthma, stroke and heart disease, diabetes, obesity, and changes linked to dementia.

"The health problems resulting from exposure to air pollution have a high cost to people who suffer from illness and premature death, to our health services and to business. In the UK, these costs add up to more than £20 billion every year."

The report also highlighted an often overlooked section of the environment - indoor space.

Kitchen products, faulty boilers, open fires, fly sprays and air fresheners can all cause poor air quality in homes, work spaces and schools.

The report calls on political leaders at a local, national and EU level to introduce tougher regulations, including reliable emissions testing for cars.

It adds that local authorities need to act to protect public health when air pollution levels are high.

When these limits are exceeded, the report says, local authorities must have the power to close or divert roads to reduce the volume of traffic, especially near schools.

The report adds that air pollution monitoring by central and local government must track exposure to harmful pollutants in major urban areas and near schools.

These results should then be communicated to the public in a clear way that everyone can understand, according to the report recommendations.