We must learn to balance\u00a0risk and freedom, says\u00a0John Ashton in this month's Soapbox Most of us enjoy a love-hate relationship with our cities.\u00a0We expect them to provide for a wide range of our needs and expectations, yet sometimes they overwhelm us and we seek the open horizons of the fells or shoreline. We yearn to re-establish a connection with nature and the seasons, which can seem elusive when surrounded by bricks and mortar and a night sky devoid of stars because of light pollution. From biblical times people have sought refuge in cities and escape from the narrow parochialism of the village, where bigotry can rear its head and xenophobia is a close cousin of intolerance of difference. Strength in numbers can be a big pull if your lifestyle falls outside accepted norms. Yet the notion of city as nirvana has never gone unchallenged. The pull and push factors that generate rapid urbanisation have always brought public health challenges in their train. We know from public health academics such as the late Thomas McKeown of Birmingham that disease occurs in populations when they migrate or their habitat and adapted way of living is changed. Cholera flourished in the teeming slums of Victorian England and it took the galvanised efforts of civic leaders (the church, the press, the business community and early health professionals) acting through the Health of Towns Association to achieve sanitary reform. That reform gave them the legislative and financial tools to tackle the urgent issues of the day \u2013 safe water and sewerage, paved streets and refuse collection, housing standards, food hygiene and a subsequent plethora of local authority provided public services. The work of these early pioneers was driven by the so-called sanitary idea, much espoused by president of the Board of Health, Edwin Chadwick. At its heart was the need to separate human and animal waste from food and water. The responses were typically Victorian, rather mechanistic but very determined. For Chadwick this took the form of the egg shaped, brick lined sewer pipe \u2013 and his obsession with finding the right way of doing something and then doing that everywhere. The town of Liverpool under its triumvirate of Duncan (medical officer), Fresh (sanitary inspector) and Newlands (borough engineer) put in 20 miles of such sewers in 20 years and the country followed over the next couple of decades.\u00a0 The impact of such measures was significant. As the nature of infectious disease came to be better understood, and the Pasteurs revealed the germ theory of infection, prevention and personal hygiene took their place alongside environmental action. Town planning joined the party and model towns and cities began to separate out living areas from the industrial and recreational. Salubrity was embraced as a core municipal function and local authorities began developing a wide range of public services encompassing housing, parks and gardens, swimming baths, social services, schools, abattoirs, tramways and gasworks and much beside. Over 100 years later much has changed but urbanisation has gathered pace. A majority of the world\u2019s population now lives in large towns and cities, some of them huge. Many accommodate vast slum areas where to the traditional problems of infectious diseases have been added the modern scourges of non-infectious and degenerative disease associated with populations that have begun to live for life spans undreamed of by our great great grandparents. Then there are the lifestyle diseases associated with the existential dilemmas of a post religious age where each of us must find our own path, negotiating the rules and ethics of a much more fluid social contract. This contract is both more liberating and more daunting than when churchgoing was the norm, everybody knew their place, and the state acted as enforcer of the status quo. Cities of today are expected to meet even more of our personal ambitions. They must simultaneously be places to grow people in, to offer them the optimal amount of test and challenge, rites of passage, opportunities and support in sickness and in health. We have begun to redefine how we understand them, as ecological habitats and as building blocks of society. The challenges in developed countries are no longer the cholera and drains but issues such as depression, drugs and alcohol and dementia. We are no longer subservient to handed-down rules, but autonomous beings seeking to negotiate paths towards our dreams, and if the questions of health and wellbeing are about anything, they are about co-production and co-maintenance. The freedom to take and manage risk is a genie that is out of the bottle. The search for a common game board for the modern city has barely begun. So in taking stock in 2012, over 150 years after the first Public Health Act, there are many questions to ask \u2013 ethical and political ones to do with power and control, governance and autonomy, and freedoms of the individual and the collective. Such things come into prominence when we focus on behavioural issues such as alcohol, drugs, violence and sexual expression. One thing is certain: the city is here to stay and there is much to be said and done if the dreams of liveable, aspirational and sustainable cities are to be available to all those who seek their joys and frustrations. Professor John Ashton CBE is regional director of public health for the North West. He will be delivering the Alison Chesney & Eddie Killoran Memorial Lecture on 22 October in London. Visit www.kachange.eu to reserve a place.