Ambient air pollution, like smoking, can seldom be definitively linked to individual cases of debility or premature death, but it greatly increases the risks. In Choked, Beth Gardiner reports that it cuts short about 7 million lives worldwide every year. Recent research suggests the actual number is closer to 9 million, or roughly one in nine of all deaths. Whatever the precise figure, air pollution – principally nitrogen oxides and tiny particles known as PM2.5 – kills more people than smoking, and more than Aids, diabetes and traffic accidents combined. Over 40% of Americans and an astonishing 95% of people worldwide breathe polluted air every day. A new study finds that in south Asia, children can expect to have their lives cut short by 30 months, and in sub-Saharan Africa by 24 months. It reduces average life expectancy in Britain by a year and a half and in Germany by over two years. Across Europe it kills more than 15 times as many people as car crashes. Many who do not die as a result of air pollution struggle with its effects on their hearts, lungs and brains. New findings have even linked it to psychotic experiences in young people.

Gardiner, an American journalist living in London with her British husband and their young daughter, found herself made deeply ill at ease by the “stew” of diesel fumes in her adopted city, and set out to discover what is being done about it. An experienced reporter, she takes her inquiry global. Travelling to India, China, the US, Malawi, Poland and Germany as well as investigating her own neighbourhood, she meets some of those suffering from air pollution’s effects. She speaks to researchers, regulators, campaigners and others who, over years and decades, have tried, and sometimes succeeded, in improving conditions, as well as some who believe attempts to regulate or restrict emissions are often misconceived.

“Invisibility,” Gardiner notes, “is a strange feature of this crisis.” As an environmentalist in Los Angeles puts it to her: “You see one person run over in the street and you’ll never forget it, but thousands dying from the effects of dirty air will never even faze you.” It is only through the careful application of statistical techniques that the impact has become apparent. Landmark research such as the Children’s Health Study in California found in 2004 that children breathing the dirtiest air were nearly five times as likely to experience 20% weaker lung function, and that for every 100 children who grew up with the worst pollution at least six would be burdened with lifelong health problems.

Gardiner examines some of the greatest missteps, such as Europe’s switch to diesel engines for private cars in the 1990s

Gardiner is nuanced but sharp in her judgments. She is concerned with the particularities of real lives as well as the particulates that often blight them. You couldn’t ask for a better guide for non-specialists and concerned citizens. Choked contains an especially interesting account of the US Clean Air Act of 1970, which remains one of the most important pieces of environmental legislation passed anywhere. It is a key reason why many Americans breathe air that, while still often dirty and dangerous, is much lower in pollutants directly injurious to health than it was in the past, and typically cleaner than the air that most Europeans breathe. Americans emit more carbon dioxide per head, but this is not directly toxic. Central to the success of the act is the idea that human health should come before company profits. No less remarkable from a contemporary perspective is that, at inception, the act received near universal assent from both Republicans and Democrats. That consensus was shortlived, however. The Trump administration’s efforts to unravel pollution controls are only one episode in a decades-long battle.

Facebook Twitter Pinterest An Ultra Low Emission Zone will soon be introduced in London. Photograph: Paul Lawrenson/Alamy

Gardiner also examines some of the greatest missteps, notably Europe’s large-scale switch to diesel engines for private cars in the 1990s. This was undertaken in the belief it would help reduce emissions of carbon dioxide, which it largely failed to do. Instead it has exposed millions of people to higher levels of nitrogen dioxide, a dangerous pollutant. Choked lays out in shocking detail how Volkswagen and other manufacturers got away with concealing the truth about illegal emissions from their vehicles for so long. But car manufacturers alone are not to blame for the terrible state of air in much of Europe. Gardiner considers London, and writes: “Instead of trying to solve the problem, David Cameron’s government, then Theresa May’s, put their energy into fighting off lawsuits demanding a serious pollution strategy, and seeking extensions to EU air quality mandates. As mayor, Boris Johnson delayed and diluted his predecessor’s more aggressive cleanup plans, and even sprayed dust suppressants near pollution monitors to artificially lower readings.” The government, however, launched an ambitious Clean Air Strategy in January, and Sadiq Khan, the current mayor, is overseeing the introduction of the Ultra Low Emission Zone on Monday.

But Gardiner contrasts London’s record with that of Berlin, where the increasing availability of attractive, affordable and readily available alternatives to passenger cars has delivered substantial improvements in transport connectivity, quality of life and health.

Air pollution is less severe in parts of China than a few years ago, but current global trends suggest a grim future

In a lively report from Delhi, a megacity with perhaps the dirtiest air of all, she shows how, after initial success in the early 2000s with the introduction of compressed natural gas for motor vehicles, Indian authorities have repeatedly struggled and failed to tackle air pollution that is now at crisis levels. Some measures have penalised the poor and vulnerable without substantially reducing emissions. Meanwhile, emissions from coal-fired power plants persist almost unchecked.

The biggest sources of dangerous air pollution in rural India and in large parts of Africa, however, are the simple household fires on which people cook their meals. Fuelled by “biomass” such as wood, brush and cow dung, these are responsible for nearly 4 million deaths a year. Women and girls, who do most of the cooking, are disproportionately affected – something Gardiner witnesses firsthand. In Malawi, pneumonia, often caused by cooking fires, is the single biggest killer of children under five. The good news is that technical solutions such as electromagnetic induction stoves that can be charged by solar panels are looking increasingly affordable.

China’s economic miracle has come at a price of an “airpocalypse”, with many cities shrouded in poisonous smog for much of the year. Gardiner’s report of attempts to tackle the challenges includes both a warning and an inspiring example. The warning concerns the case of Chai Jing, a journalist from China Central Television who made a documentary about the crisis. More than 200 million people watched Under the Dome within days of its online release in 2015 – a big audience even for China. There is little question that central government recognised the importance of the issues addressed in the film (which can be found with subtitles on YouTube), but Chai appears to have made an unforgivable mistake by making it without official approval. Gardiner tries to track down a woman who in any other country would be a celebrity, but Chai has disappeared without trace. The inspiring example is that, thanks to such environmental activists as Ma Jun, data on air and water pollution levels at critical sites across China is freely available online to everybody in real time. Nothing like this exists elsewhere, and, in a country where the government increasingly uses information technology to control its citizens, Ma is doggedly hopeful. “The moment … you give people the truth there’s no way for you to backtrack,” he tells Gardiner.

Air pollution is less severe in parts of China than it was a few years ago, but current global trends suggest a grim future. As David Wallace Wells notes in his recent book The Uninhabitable Earth, climate change this century could increase the number of excess premature deaths from air pollution alone more than 15‑fold. Yet Gardiner remains guardedly optimistic. With the precedent of values-based legislation such as the Clean Air Act, and mobilisation for the Green New Deal in the US, a shift away from fossil fuels that poison our bodies and wreck our planet is possible. “While it can be difficult to imagine” a better world than the one we know, she concludes, “it is within our reach”.

• Caspar Henderson’s A New Map of Wonders is published by Granta. Choked is published by Granta (£14.99). To order a copy go to guardianbookshop.com. Free UK p&p on all online orders over £15.