Pollution has existed for centuries in various forms. Ancient cultures produced air pollution from activities like metal forging. During the Industrial Revolution, the introduction of factories and consumption of fossil fuels caused unprecedented levels of air and water pollution. Modern awareness of pollution issues grew after events like the Great Smog of 1952 in London and publication of books like Silent Spring, leading to increased environmental regulations in the 1960s-1970s. Pollution remains a global problem today.