Alarm over air pollution
Over 90% of the world’s population live in locations with dangerous levels of toxic airborne particles
Why is air pollution such a fast-growing concern?
Nothing is more vital to life than breathing: in a lifetime, about 250m litres of air passes through your lungs. Yet walk along a busy city street and you will inhale something like 20m particles in a single lungful.
Toxic air is now the biggest environmental risk of early death, responsible for one in nine of all fatalities. It kills 7 million people a year, far more than HIV, tuberculosis and malaria combined. Dr Maria Neira, the World Health Organisation director with responsibility for air pollution, is blunt: “It is a global public health emergency.”
How much does it cost us?
The lost lives and ill health caused are also a colossal economic burden: $225bn in lost labour income in 2013, or $5.11tn per year, if welfare losses are added in, according to a 2016 World Bank report.
It is only in recent decades that the damage to health has become clear, and in the last few years that the crisis has received widespread attention, thanks to research revelations, government legal defeats and the Volkswagen diesel scandal. But there is a silver lining to air pollution’s cloud of smog: action to cut it not only brings immediate benefits but also helps fight climate change in the longer term.
Who does it affect?
Over 90% of the world’s population lives in places where air pollution is above WHO guidelines. It is worst in south and east Asia, where most of humanity lives, with traffic, dirty industry and the open burning of waste. India has almost half of the top 50 most polluted cities in the world, China has eight and Iran has three. Africa is highly polluted but little measured: in 2015 Paris had three times more monitoring stations than the whole of Africa. But air pollution affects rich nations too.
“The trends are positive if we look at the last 50 years, but it depends how many deaths are you ready to accept,” says Neira. “We still have 500,000 deaths in Europe [per year] and this is totally unacceptable.” Children are uniquely vulnerable and 300 million live in places where toxic fumes are six times higher than international guidelines.
Are there different types of air pollution?
Yes. The most damaging but best understood are tiny particles, which harm the lungs and enter the bloodstream. They are increasingly thought to enter vital organs, including the brain, and have been shown to reach the liver, spleen, kidney and testes in lab animals. The particles are made of black carbon, nitrates, sulphates, ammonia or mineral dust. Most are produced by burning fossil fuels or wood.
In some countries, improvements have been made to coal-fired power stations and cars, but other sources of pollution lag behind. Farming is one source, with ammonia from manure and fertilisers blowing into cities and forming particles.
Nitrogen dioxide, produced by diesel vehicles, not only forms particles but is now known to cause harm when breathed as a gas. It is still illegally high in much of urban Britain, where it results in about 23,500 early deaths.
Other pollutants include sulphur dioxide, which is still very high in ship and aviation fuels. Ground-level ozone, which forms on sunny days, harms not only people but also crops: 7-12% of the global wheat crop is estimated to be lost in this way; in India, crop yields are reduced by 28%.
There are some natural sources, such as dust storms and smoke from forest fires, but human-caused pollution far exceeds these. Outdoor air pollution causes 4.2m early deaths, says the WHO.
What about indoors?
This is also a huge killer, causing 3.8m early deaths. Half the world’s
population cook on open fires with dirty fuels such as wood, dung and charcoal. Kerosene in wick lamps also produces dangerous smoke.
More people are getting access to better stoves and cleaner fuels. Among farmers in Xuanwei, China, lung cancer cases fell by 40% when they switched to stoves with chimneys.
What harm does air pollution do?
It is easier to ask what harm air pollution does not do. Research links toxic air not only to almost every part of the body, but also the brain.
The landmark research linking air pollution to lung diseases, heart attacks and strokes – the Harvard six cities study – was first published in 1993. Since then dirty air has been linked to many conditions, such as diabetes. Air pollution contributed to 3.2m new cases of this illness in 2016, according to one study. Kidney disease appears to be influenced by air pollution, as does Alzheimer’s. Skin ages more rapidly in dirty air.
The research on babies and children is particularly worrying. A large recent study found toxic air significantly increases the risk of low birth weight, leading to lifelong damage to health.
Millions of premature births may be linked to air pollution; another study makes the connection to birth defects and another to cot deaths. The first direct evidence of pollution particles in mothers’ placentas has also been revealed.
As children grow, asthma and stunted lung growth have a serious impact, but also affect the ability to learn in school.
The estimated annual death toll of 7m is an underestimation, as it only includes particle pollution and the five most firmly linked causes of death, such as heart attacks. Early estimates using improved models suggest a total figure of 9m from particle pollution. Even this is only “the tip of the iceberg”, according to researchers. Exposure to air pollution is likely to damage the health of almost everyone. The WHO is clear: “The burden of disease from [outdoor] air pollution is expected to greatly increase.”
Can I protect protectprotectmyself? myself?
Masks are now commonly advertised, but experts say they are of limited use unless they have an airtight seal on the face, which is rare.
Giant towers, street-side benches and living, green walls have all been proposed to filter dirty air. A new bus aims to filter air as it travels around Southampton in the UK. Pollution-monitoring apps and walking routes keep pedestrians away from the filthiest roads. Trees can help, unless they block the breezes that blow pollution away.
People in cars are often exposed to more pollution than those outside. Closing the air circulation in your car before hitting the city is a good idea.
Isn’t that treating the symptom, not the cause?
Yes. The only practical way to tackle the global health emergency is to cut levels of pollution at source. There is an ethical angle too, says Prof Gary Fuller, at King’s College London: “Morally it is not right to make the victims change their behaviour, instead of the culprits.”
Poorer people are also most exposed to air pollution. “There are huge injustices at the heart of the air pollution problem,” says Fuller. “By using our air to dispose of their waste, polluters are destroying a shared resource and avoiding the full cost of their actions.”
“There are two big transitions we need to have,” says Neira. “One is a healthy energy transition and the other is the healthy urban planning transition. We need to stop the use of coal, to stop the massive use of private cars in cities and make our buildings more efficient.”
Coal burning is declining globally and China has shown how industrial pollution can be curbed. Particle pollution is down by a third, just four years after a “war on pollution” was declared, and eight after Beijing’s air was labelled “crazy bad” when pollution leapt off the charts. But cities around the world are expanding rapidly, with 4.2bn urban dwellers set to swell to 6.7bn by 2050.
How those growing cities are constructed is vital, say experts. Mobility should focus on walking, cycling and public transport - even electric vehicles throw up particle pollution from road abrasion and brake dust. The remaining cars and lorries need to be set – and stick to – much stricter pollution controls.
Buildings ought to be heated and cooled using renewable energy and waste should not be burned without stringent controls.
Progress is being made. Some Dutch and Danish towns have turned their back on cars and Seoul in South Korea has demolished 15 expressways in favour of bus lanes and a new river. But some motoring lobbies and car manufacturers remain obstacles.
Neira, a former health minister in Spain, says politicians should play the health card: “If you reduce cases of asthma, everybody will love it.” Other reasons for action are the climate change benefits of cutting coal, oil and gas burning and the reduction in obesity that follows more active travel, such as cycling.
What must be done to end the air pollution emergency is not the issue, says Neira, it is the lack of serious political will: “There are plenty of ideas and solutions. It takes leadership.”