Cities particularly affected included the main UK centers, and their airports such as London Heathrow, Gatwick, Manchester, Birmingham and Glasgow, as well as European cities such as Amsterdam, Brussels, Paris, Zurich and Milan. Visibility at these times could become as low as a few feet (hence the "London fogs" of movie fame) and when combined with the soot created lethal long-persistence smog. These conditions led to the passing of the UK's "Clean Air Act," which banned the burning of smoke-producing fuel.