THE CHANGE IN SUB-SPECIES OF PARTICULATES MATTER (PM10) BEFORE AND AFTER AN INTERVENTION TO RESTRICT SULFUR CONTENT OF FUEL IN HONG KONG

ABSTRACT

In July 1990 in Hong Kong, the sulphur content of fuel was restricted to d 0.5% by weight, leading to an immediate reduction in sulphur dioxide (SO2). An analysis of the intervention showed a substantial reduction in deaths classified by All causes and Cardiorespiratory rubrics but not neoplasms or gastro-intestinal disease (Lancet 2002; 360:1464-52). We studied the effect of the intervention on sixteen PM10 sub-species. Concentrations of chemical constituents were compared between pre and post intervention periods. Four out of sixteen (Br, Zn, Ni and V) sub-species, from vehicle emissions and oil fuel combustion, showed immediate and sustained decreases (paired t-tests p<0.05) in their half-yearly means up to 2 years after intervention. However, the pattern was biphasic with further moderate increases observed after the initial sharp fall in mean concentrations. The intervention not only led to a decline in concentration of SO2 but also to the reduction of some PM sub-species that may be associated with the observed health gains. Further investigation is needed to clarify the cause of these variations in subspecies, including the switches to different types and sources of fuel oil in the periods following the initial six months post-intervention.