Trends in the deposition of sulphate and total solids in London.

The earliest measurements of sulphate deposit in London were made in 1870, although they can be used to construct a contour map indicating elongation along the direction of the prevailing wind and rather higher values in the lee of the city they cannot be used to establish a deposition rate. However, an initially fragmentary record for the east part of the city of London begins in the 1880's and a gradual decrease of sulphate deposit is evident for much of the period. The record of the deposit of solid matter begins in 1914 and shows a decline throughout the measurements. The period of decline precedes air pollution control legislation and is attributed to social and geographic changes.