Decrease of lead concentrations in the Western Mediterranean atmosphere during the last 20 years

Concentrations of lead (Pb) in the atmospheric aerosol were monitored in 198687, 199293, 1995, 199798 and 20032005 at a North-Western Mediterranean coastal sampling station. After the implementation of antipollution policies on automotive Pb in the second half of the 1980s, Pb concentrations were markedly lowered and then the decrease slowed down, at the latest in 2003, resulting in average concentrations varying between 6.6 and 5.8 ngm3 in 2004 and 2005, respectively. This represents a decrease by a factor of 82%, approximately, between 198687 and 2005. Reproducible seasonal patterns are observed, with highest Pb loads occurring at the end of winter and at the end of summer/beginning of autumn. The slowing down of aerosol Pb concentration decrease in the troposphere is expected to be rapidly observed in the Western Mediterranean water column.