A new study has linked diesel fumes to particulate matter that directly stimulates nerves in the lungs, potentially affecting underlying conditions.
Measuring city pollution throughout the world is nothing new, with an annual report card provided by the World Health Organisation (WHO) every year showing the best and worst places to take a breath.
There are ups and downs, of course, with some areas hit particularly hard during special events, others during storms.
But which ingredients for air pollution are human-made? Factories? Of course. Transport? Almost certainly.
The problem, though, is that we still know very little. Yesterday, a study emerged that linked air pollution with poor sleep.
Elsewhere, heart attacks, strokes and thousands of deaths a year are reported.
For cyclists, it’s particularly troubling, with daily commutes often involving the direct inhalation of fumes from cars.
A new study from Imperial College London suggests that diesel fumes trigger respiratory reflexes, which could potentially worsen underlying conditions, such as asthma.
Published in the Journal of Allergy and Clinical Immunology, the report claims that by-products from burning diesel fuel – called polycyclic aromatic hydrocarbons – directly stimulate nerves in the lungs, causing a reflex response in the airways.
“In major European cities like London, we are already exceeding the recommended levels for air pollution, and these findings provide another reason why we need to curb these levels,” said Prof Maria Belvisi, one of the authors of the study.
“Pollution will affect everyone, but it affects people with underlying conditions, such as asthma, even more.”
Last month, the UK government was accused of “running scared” of diesel drivers as it delayed the publication of its clean air plan. When it did emerge, it was widely criticised.
The UK is not the only country struggling to keep a grip on its pollution issues, however, with numerous ingredients making for potentially unsafe environments.
Of all the urban areas around the world with air monitoring capabilities, an awful lot are breaching what the WHO determines to be safe levels.
Monitoring two types of small (PM10) and fine (PM2.5) matter in the air across 795 locations in 67 countries, only one in five places were deemed safe last year.
“This study, which brought together a multidisciplinary team of scientists, helps to address the previously unknown effects of particulate air pollution on respiratory symptoms,” said Prof Terry Tetley, co-lead author.
“The findings further highlight the potential health impacts of urban air pollution on the public, particularly on those with underlying health conditions.”
However, things will inevitably change.
In air transport, for example, the introduction of biofuels drastically alters the pollution that planes emit into our atmosphere. While that plays little part in city pollution, it hints at where efforts are focused.
Meanwhile, electric vehicles will soon dominate our roads, potentially clearing up significant chunks of city air pollution.