Dust and Human Health - Mineral Dust: A Key Player in the Earth System - page 393

have begun to focus on the potential health effects of dusts transported from large
primary sources such as the Sahel/Sahara and Asia. In Europe, Perez et al. ( 2007 )
examined the relationship between coarse particles from Saharan dust and daily
mortality in Barcelona, Spain. They observed that daily mortality increased by
8.4 % (per increase of 10 g/m 3 PM10) on Saharan dust days in Barcelona, but no
increased risk was observed with PM2.5 (Perez et al. 2007 ). Chemical analysis to
examine potential compositional differences did not explain the differences (Perez
et al. 2007 ). Similar results for far-traveled dusts were observed in studies elsewhere
in Europe (Jimenez et al. 2010 ; Mallone et al. 2011 ).
Studies have also been done for areas that are closer to the source locations for
major dust events. Lopez-Villarrubia et al. ( 2010 ) found increased rates of respi-
ratory mortality, 4.9 % for each PM10 increase of 10 g/m 3 , in the Canary Islands
linked to dust events sourced in nearby Africa. In Asia, similar associations between
dust events and emergency room visits, hospitalizations, and deaths were observed.
In Taiwan, emergency room visits for cardiovascular and respiratory illnesses were
increased following dust storms from Asia (Chan et al. 2008 ). In Taipei, Chan and
Ng ( 2011 ) found an increase in the number of nonaccidental and cardiovascular
deaths on dust storm days over a 14-year period. Hashizume et al. ( 2010 ) found
conflicting results in a review of Japanese literature for evidence of potential health
problems related to Asian dust events. Their analysis indicated that some studies
suggested an increase in mortality and hospital admissions related to dust exposure,
while others did not demonstrate any statistically significant associations. A study
of a far-traveled Gobi desert dust event, however, found no evidence of increased
hospitalization in a retrospective examination of hospitalizations following the dust
event in British Columbia (Bennett et al. 2006 ).

15.5.4 Exposures to Agricultural Dusts

We have included as part of this discussion occupational exposures to agricultural
dusts, as results indicate respiratory disease may be a chronic condition among
farmers. It is unclear if these exposures could be extended to nearby communities
as we were unable to locate studies linking nonoccupational agricultural dust
exposures to health risks for community members residing near farms. In the United
States, many farm operations are small and do not fall under the jurisdiction of the
Occupational Safety and Health Administration (OSHA), and the cause and extent
of disease in farmworkers is difficult to determine (Kirkhorn and Garry 2000 ). In
addition to field activities such as plowing, grain handling and harvesting may
also expose workers to high concentrations of inorganic dusts such as crystalline
silica (quartz) and noncrystalline silica (diatomite) (Kirkhorn and Garry 2000 ).
Green et al. ( 1990 ) characterized mineral dusts associated with farm activities in
rural Alberta, Canada, and found that the respirable mass fraction (particles with
diameters <5 m) was 50 % or greater and free silica content ranged from 1 to 17 %.