Abstract
Long-term visibility trends at 22 sites, including urban, coastal and inland rural locations throughout the UK, are analysed. Significant improvements in annual median visibilities are observed at most sites, especially those in urban-industrualised areas, where visibility is now similar to that in many rural locations. Visibility trends are related to changes in national patterns of energy consumption and air pollution emissions, with the most important influence being the decline in the use of coal and reduction in domestic smoke emissions. Increasing emission from motor vehicles is suggested as a potentially significant obstacle to further improvements in visibility.