AIR pollution can lead to babies being born with shorter bodies and smaller heads, according to Scottish research which found that high exposure to toxic fumes during pregnancy is nearly as harmful as smoking.

A study by Edinburgh and Aberdeen universities found that Scottish babies exposed to toxic gases and particulates breathed in by their mother, such as traffic fumes, were born with smaller heads and shorter bodies.

A similar outcome was observed in babies whose mothers smoked during pregnancy but were exposed to less pollution.

The findings are particularly worrying because the study — the largest of its kind so far conducted — only examined the effects of pollution in the northeast of Scotland, where air quality is relatively good compared with congested areas such as Glasgow, Edinburgh and London.

It comes just weeks after another study at Edinburgh University showed that nano-sized particles found in traffic fumes can damage the immune system’s ability to kill viruses and bacteria. The emissions are also known to aggravate lung conditions, and have even been linked to an increased risk of dementia.

Dr Tom Clemens, who led the latest study, has called on the World Health Organisation (WHO) and the EU to urgently review their definition of "acceptable" emissions levels amid concern they are still too high.

He added: "Our findings suggest that there may not be a truly 'safe' level of exposure during pregnancy.

"A foetus with a non-smoking mother exposed to high pollution levels is only slightly better off than one with a smoking mother exposed to low levels of pollution. This implies that the effect of exposure to the highest They detected average concentrations of 7.2 micrograms per metre cubed — well below the annual average of 10 micrograms per metre cubed that is deemed acceptable by WHO."

Data on foetal growth was gathered from ultrasound scans and maternity records for almost 14,000 pregnancies in northeast Scotland between 2002 and 2011. Lifestyle factors, such as smoking, were considered. Air quality at postcode level was determined using dispersion models based on UK government data.

Unlike previous air pollution studies, the investigation by Clemens and his team looked at the effect on developing foetuses of microscopic specks of dust and soot that can enter the lungs and bloodstream.

Chris Dibben, a co-author of the study, added: "Although most parents will be aware that their smoking may be harming their unborn child, we wonder whether there is an equal awareness that air pollution can have a similar level of impact on the growth of the child in the womb, even in a relatively unpolluted region like northeast Scotland."

The study is published in the scientific journal, Environment International.

In February, the European Commission admitted that air quality laws had been flouted in more than 130 cities across 23 of the 28 EU member states, including the UK. It is estimated to cut average life expectancy in Scotland by three to four months and causes 2,500 premature deaths.

The UK Government has pledged to ban the sale of new diesel and petrol cars by 2040 as part of efforts to reduce air pollution from traffic.

It has been estimated that 59 per cent of the British population are living in towns and cities where nitrogen dioxide pollution breaches the lawful level of 40 microgrammes per cubic metre of air.

In January, Hope Street in Glasgow was named the most polluted street in Scotland with average nitrogen dioxide levels which were more than 60 per cent above the legal limit.