Evidence for increasing concentrations of primary PM_(10) in London

摘要

Although annual mean concentrations of PM_(10) in and around London reduced during the 1990s, concentrations have been relatively stable since, with small increases during 2001-2003. A modelling method was used to apportion the measured annual mean concentration of PM_(10) between primary, and secondary and natural sources at monitoring sites in and around London between 1997 and 2004. The annual mean concentration of PM_(10) from primary sources reached a minimum during 1998. Between 1998 and 2003 the greatest change in the annual mean concentration of primary PM_(10) occurred at sites adjacent to busy roads: Marylebone Road (7.0 ± 2.6 μg m~(-3)), Wandsworth 4 (6.0 ± 1.1 μg m~(-3)) and Ealing 2 (4.5 ± 1.4 μg m~(-3)). The smallest change in the concentration of PM_(10) from primary sources occurred at background locations in towns outside London. It is therefore likely that the additional primary PM_(10) arose from road traffic. These increases in PM_(10) from primary sources contradict emissions inventory estimates that indicate reductions in primary PM_(10). The annual mean concentration of PM_(10) from secondary and natural sources declined by 2.0 ± 3.0 μg m~(-3) or 11 ± 16% between 1997 and 2003. The annual mean concentration of PM_(10) from these sources reduced until the year ended 1st July 2001 and then increased during the remainder of 2001, 2002 and 2003.