Anyone living in a busy town or city can see, feel and even taste air pollution on a daily basis, yet the true extent of the health risks associated with nitrogen dioxide (NOx) and particulate matter (PM) emissions is only beginning to be understood. We talk to an expert from the British Lung Foundation and analyse the latest research.
A 2016 report by the Royal College of Physicians (RCP) and of Paediatrics and Child Health (RCPCH) concluded that each year in the UK around 40,000 deaths are attributable to exposure to outdoor air pollution. The annual cost to sufferers, the NHS and business is thought to be more than £20 billion.
Poor air quality disproportionately affects the most vulnerable in society - those living in deprived areas, those who live, learn or work near busy roads, young children and the elderly, and those with existing medical conditions.
Research published this year by the World Health Organization (WHO) revealed more than 40 towns and cities in the UK are at or have exceeded WHO air pollution limits, with London, Manchester and Swansea among the worst offenders.
"People in towns and cities across the UK are living in areas with dangerous, and in some cases illegal, levels of air pollution - that could be putting them at risk of a whole range of health problems further down the line," says Sarah MacFadyen, head of policy at the British Lung Foundation (BLF).
"For people who are living with a lung condition, something like asthma or chronic obstructive pulmonary disease (COPD), they will often find that on days when pollution levels are high, sometimes they can't even leave their house because it is so much harder for them to breathe and it's making their symptoms so much worse than normal."
What is air pollution?
Health-wise, the most harmful air pollutants are gases such as nitrogen dioxide (NOx) and solid and liquid particles in the air, known as particulate matter (PM).
NOx in exhaust fumes emitted by petrol and diesel vans, lorries and private cars is a major problem In densely populated towns and cities. High levels of NOx are also found close to indoor gas cookers.
PM, again primarily from road traffic in urban areas, is separated into two categories: larger particles such as dirt or dust (PM10) and particles smaller than 2.5 micrometres (PM2.5), the latter being more harmful since they travel more deeply into our lungs and cardiovascular system.
The recent WHO report found that in the UK, Scunthorpe had the highest estimated level of fine-particle air pollution at 15 micrograms per cubic metre (according to data from 2013).
Other air pollutants include sulfur dioxide (SO2) from the burning of fossil fuels, mostly power stations; ground-level ozone caused by chemical reactions between natural, traffic and industrial pollution in strong sunlight; and metals including lead emissions from iron and steel factories, mercury and arsenic.
How does air pollution impact health?
Air pollution affects major organs including the lungs, pancreas, heart and brain, and is linked to respiratory disease, cancer, asthma, stroke and heart disease. There is also emerging evidence that it could be linked to diabetes, obesity, and changes related to dementia.
Chair of the Primary Care Respiratory Society, Dr Noel Baxter, a GP and medical adviser at the BLF, says that the sudden or gradual worsening of asthma or COPD and other long-term lung conditions are the pollution-related problems that he encounters most often in patients.
"Breathing in dirty air is linked to lung cancer, asthma, heart disease and stroke," he says. "It can also stunt children's lung development, leading to chronic health problems later in life."
New data released by the Office for National Statistics reveals a record 1,320 people died from asthma in England and Wales in 2017, an increase of 25% over a decade.
"From birth our lungs develop and grow, and at about age 25 they have reached their maximum potential," Baxter explains. "Damage in early age can be irreversible - it is therefore vital that our young people, who are expected to live so long, have the best lungs they can have at 25, so poor lung function doesn't disable them when they may be having an otherwise healthy retirement."
Issues with diagnosis
Identifying pollution as the sole cause of conditions such as asthma or COPD can be tricky, however.
"The evidence is clear that dirty air affects all our health, and pollution is especially harmful to anyone living with a lung condition," says Baxter.
"However, there are no specific symptoms or clinical signs that tell us that this is the cause, in the way that, say, a high temperature may suggest an infection-induced flare-up.
"It is likely we as primary care health professionals probably don't appreciate that air pollution is causing our patients to turn up in surgery. The same can be said of A&E services, as they might see patients for which air pollution is the straw that breaks the camel's back."
How can I protect myself?
In addition to better education and research into the health effects of pollution, measures to tackle inequality, and better regulation and pollution monitoring, the RCP/RCPCH report recommends that we, as individuals, take affirmative action to tackle poor air quality.
So, consider trying cleaner alternatives to car travel, promote energy efficiency at home, keep gas and fuel appliances in good repair, and demand that your local council and MP tackle the problem.
"We have an air pollution crisis in the UK, and the government must take action to protect the nation's health," states Baxter. "The best thing to do to protect yourself is to reduce exposure to air pollution, by avoiding busy roads and streets. You can also be exposed to more air pollution inside your car, especially if you're stuck in traffic, than if you walk or cycle.
"So public transport, cycling and walking should always be the go-to option for short journeys. You can also keep an eye on pollution levels in your area on the UK Air website or on the Defra Twitter page."