The UK’s failure to meet World Health Organisation standards limiting the amount of ultra-fine particles in the air represents a major danger to health that is only now being recognised, experts claim.

Studies published this year link the particles to cancers, lung and heart disease, adverse effects on foetal development, and poor lung and brain development in children. They are considered a key threat to health because they go deep into the lungs and then reach other organs, including the brain. But European standards allow the levels of particles in the air to be 2.5 times higher than those stipulated by the WHO.

Professor Annette Peters, director of the Institute of Epidemiology at the Helmholtz Zentrum, Munich, said Europe – and the UK – urgently needs to introduce tougher standards. She said: “Particles are a major and invisible danger to our health, especially in London and our big cities.

The US has a standard of 12 micrograms of ultra-fine particles per cubic metre, while the WHO standard is 10 micrograms.

“We [the UK and EU’s limits] are currently at 25 micrograms per cubic metre – double the US standards,” said Peters, who warned that scientific evidence confirming the threat they pose to human health “has really strengthened this year”.

“We initially had evidence of the effect on the lungs and heart, but now we also have evidence that it alters the metabolism as well as impacting the brain.”

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Vehicle emissions are predominantly to blame, but domestic heating systems and industrial pollutants are also factors. “Recent studies from London and our work in a medium-sized community in southern Germany show there really is evidence that the ultra-fine particles go beyond the lungs,” Peters said.

“Colleagues of mine have been able to show that ultra-fine particles are able to reactivate the herpes virus which lies dormant among carriers.” She said urgent studies were needed to look at the impact of fine particles on cognitive development, especially in children. Studies have documented that adverse health effects are observed even at concentrations well below the recommended WHO levels. According to a paper, written by Peters and published in the Lancet, ambient air pollution now ranks among the top 10 major risk factors for attributable death worldwide and leads to an average loss of life expectancy of approximately one year in Europe.

Peters said ultra-fine particles could carry several thousand kilometres. “In most times you don’t see or smell it, the pollution, so it’s clear, if you look to India or the far east, the pollution is very visible. Here, we have blue skies but that doesn’t mean we have truly clean air.”

Studies in London confirm wide geographical variations in the amount of fine particles in the air. While Oxford Street suffers major concentrations, nearby Hyde Park is considered far cleaner.

Professor Jon Bennett, consultant respiratory physician and chair of the British Thoracic Society’s Board, described the particles as “a real and present health danger to society”.

“It is really concerning that babies and children are particularly susceptible as air pollution can impair immune-system development in the womb and adversely affect children’s cognitive development,” he said.

A WHO report estimated that in 2016 air pollution contributed to more than half a million deaths from respiratory tract infections in children under five years of age.

“Everyone should have the right to breathe clean air,” Bennett said. “We must have a harder-hitting and better-funded national strategy that really tackles this issue across the board – including fast-tracking the delivery of more clean air zones in our most polluted cities and areas.”