For much of the 19th and 20th centuries, London and Paris were amongst the most polluted cities in the world. The “Great Smog” of 1952 blanketed London in a sulphurous haze that killed several thousands of people within days. The River Thames, once central to the city’s life, had become so biologically dead by the 1950s that scientists described it as incapable of supporting any aquatic species.

Across the English Channel, in Paris, the Seine was no different. The river was effectively an open sewer, carrying industrial waste and untreated effluent, forcing a nationwide swimming ban that lasted nearly a century. Both cities became emblematic of the costs of industrial modernity, where economic progress was built on the steady suffocation of air and water.

A BLUEPRINT FOR REVIVAL

However, over the course of a few decades, both cities have achieved an extraordinary reversal of their ecological decline. Today, the Thames supports over 100 species of fish. The Seine, once declared ecologically irreparable, hosted open-water swimmers during the 2024 Olympics. London now brandishes the title of world’s largest urban forest, with more trees than people, estimated at over 8.4 million. Paris has reconfigured its riverbanks into green corridors and pedestrian zones.

These recoveries are the outcome of decades of deliberate urban reform, environmental regulation and a civic understanding that public health and ecological well-being are inseparable.

London and Paris were once as choked and polluted as Pakistan’s cities are today. Their remarkable recovery offers a clear blueprint…

What these cities demonstrate is that environmental collapse is not irreversible. It can be slowed, even reversed, when societies recognise that the urban and the ecological are not opposing realms. The transformation of London’s air and Paris’ rivers began with a shift in how citizens saw nature — not as an externality to be managed, but rather a broader system that must be integrated with the city’s design. That shift, cultural before it........

© Dawn (Magazines)