Impact of the 1998 Gobi dust event on hospital admissions in the Lower Fraser Valley, British Columbia.

The adverse public health impacts of anthropogenically derived particulate matter have been well documented, with measurable increases in both morbidity and mortality rates associated with high particulate matter pollution events. Most current research has focussed on the health impacts of anthropogenically derived particulate matter, and there is a distinct scarcity of literature that examines the role of naturally derived particulate matter and adverse health impacts in the urban context. This study of a Gobi desert dust event in the Greater Vancouver region of British Columbia, Canada, in spring of 1998 provided a unique opportunity to identify the adverse health effects related to naturally derived particulate matter in a large urban setting. Respiratory and cardiac hospitalizations were examined for a three-year period (January 1997 to December 1999), with the Gobi dust event occurring in late April 1998. A meteorological analogue was identified for spring 1997 in order to identify the public health impacts associated with anthropogenically derived particulate matter and those impacts associated with the presence of the Gobi desert dust. Results indicate that this Gobi dust event was not associated with an excess of hospitalizations in the Greater Vancouver region. Peak particulate matter concentrations of Gobi desert dust in the airshed were only associated with an additional one or two hospitalizations per 100,000 population for respiratory and cardiac illnesses, and these increases were not distinguishable from the 'normal' variability in hospitalization rates. Despite high particulate matter concentrations, fine particle size, presence of heavy metals in the dust and extended exposure periods, it appears that the Gobi desert dust event was not associated with significant risk to public health in Greater Vancouver, British Columbia. Therefore it is concluded that naturally derived particulate matter is more benign than particulate matter of anthropogenic origin, and thus poses a low risk to health for the general public.