In 1950s London, the impacts of air pollution were obvious in the choking fogs that shrouded the capital, reducing visibility to a few yards and breath to a laboured gasp. Eventually, the great smog of 1952, which may have killed as many as 10,000 people, and sickened an estimated 100,000, prompted action on the smoke from domestic chimneys and industry that was largely to blame. Under the Clean Air Act of 1956, coal-burning was restricted, the smogs cleared, and England could breathe again.
Unknown to most people, however, the supposedly clean air was gradually being filled with a new menace: microscopic lung-shredding particles and irritant gases such as nitrogen oxides and ozone, being spewed out in increasing volume by cars and other road vehicles, or created by the action of sunlight on air. These newer invisible forms of air pollution would eventually prove just as deadly: an estimated 40,000 people die each year in the UK from air pollution today, and globally, more than 95% of people breathe air polluted above safe levels.
Martin Williams, who has died aged 72 of the heart condition hemopericardium, was one of the first British scientists to delve into this second wave of air pollution, and in a career that spanned academia and government, played an important role in trying to reduce it. He was early to identify ground-level intrusions of ozone, now recognised as a major form of air pollution, and published one of the first papers on air pollution and health, after most people viewed the smogs of the 1950s as a problem that had been solved.
Born in Wales, in the industrial town of Mountain Ash, in what was then Mid Glamorgan, to Muriel (nee Tinkler) and Chester Williams, he had an early connection with coal, as his father served as a clerk to the National Coal Board. After Mountain Ash grammar school, he went on to take a first class degree in chemistry at University College, Cardiff, in 1968, moving across the Severn to Bristol for his PhD. He had research fellowships at the universities of British Columbia and Bradford before joining the Warren Spring Laboratory, then one of the world’s leading air quality research institutes, in 1975.
WSL was established in Stevenage in 1958, under the then Department of Scientific and Industrial Research. It took on a range of work, from attempts to synthesise oil from carbon monoxide and hydrogen, and the extraction of metals from waste, to research into atmospheric pollution, until it was merged with AEA Technology in 1994 and privatised.
The sequence of spectacular summers in the UK leading up to the record-breaking 1976 led to the highest levels of photochemical pollution ever recorded up to that time. Knowledge of the impact of such secondary pollution – which occurs when sunlight reacts with basic pollutants such as nitrogen dioxide, produced by diesel cars – was then scant. Williams co-authored a key paper in the journal Nature on ground-level ozone concentrations in south-east England in the summer of 1976, showing for the first time the harm this neglected danger posed to health.
Realising that the key measurements were from the real-world emissions of cars and lorries, rather than the engines’ performance in carefully controlled environments, Williams then led a team devising tests that would mimic authentic driving conditions. This pioneering work came decades before the Dieselgate scandal that engulfed the motor industry in 2015, when car engines were found to have been fitted with software to cheat in test conditions.
Moving in 1993 to the Department of Environment, later reorganised into the Department for Environment, Food and Rural Affairs, where he became head of the air pollution programme in 2005, Williams worked at the interface of science and public policy. His role was to translate scientific research into the formulation of policy, advising ministers and leading the negotiations for the UK on air pollution directives in the EU.
He also had a strong international focus, and was invited to join the World Health Organisation working group that formulated air quality guidelines to protect public health. For the EU’s directives on air quality - which until Brexit also applied to the UK, though successive governments flouted them - Williams co-chaired the working group on particulate pollution. He was also elected chairman of the scientific arm of the UN Convention on Long Range Transboundary Air Pollution.
In 2010, Williams moved out of government and back to a university career, as professor at the environmental research group at King’s College London. He modelled air quality impacts on health and social deprivation, and last year was named one of the UK’s three clean air champions, with a remit to bring together the UK’s air quality research base to develop practical solutions.
Though he worked in England most of his life, Williams never lost his passion for Wales, and was always ready to spark up a conversation about Welsh rugby or Cardiff’s football team. A keen cyclist, he would frequently cycle the 30 miles from home to his work in London, and back at the end of the day. He applied this passion to Wales too: he liked to point out that he had ridden the same Cardiff hills where Tour de France winner Geraint Thomas trained. At scientific conferences, Williams could just as easily be prevailed on to entertain with his ukulele as to scribble out impeccable calculations on the dispersion of Gaussian plumes on the back of an envelope.
Williams’ career exemplified the contribution of a generation of government-employed scientists, who worked at the nexus of cutting-edge research and developing policy, with public health at the core. Much more basic scientific research was carried out by government at the start of his career than by the end, by which time the relationship between universities and governments had become thornier, and the position of scientific advisors to ministers even more fraught. But as the current pandemic crisis shows, the public good will always rely on the skills of scientists who are willing to take on the tricky and often unrewarding role of advising ministers.
In 1982 he married Rosemary Hudlestone, a scientific civil servant. She survives him, along with their two sons, Tom and Anthony.
• Martin Lloyd Williams, environmental scientist, born 22 November 1947; died 21 September 2020