Dust and Human Health - Mineral Dust: A Key Player in the Earth System - page 380

have demonstrated an association between fine particulate matter (PM) exposure
and the exacerbation of cardiovascular disease (myocardial infarction and stroke),
respiratory disease (asthma, bronchitis, chronic obstructive pulmonary disease), and
resulting mortality in large urban areas (Dockery et al. 1993 ; Pope et al. 1995 and
others); however, the etiological or causal factors are not well understood.
Over the years, most studies of PM health effects have focused on urban settings
and anthropogenic (industry and combustion by-products) PM sources, but there
are few studies of contributions from natural geological sources. Geogenic PM
is produced from the Earth by natural processes (e.g., volcanic ash, windborne
ash from wildfires, and mineral dusts). Geoanthropogenic PM is produced from
natural sources by processes that are modified or enhanced by human activities (e.g.,
dusts from lakebeds dried by human removal of water, dusts produced from areas
that have undergone desertification as a result of human practices, and dusts from
agricultural fields). About 2,000 Mt of dust is emitted into the atmosphere every
year (Chap. 5 , Shaoetal. 2011 ) from geogenic and geoanthropogenic sources such
as the Sahara and Sahel in Africa.
Only recently have public health studies sought to elucidate links between the
environmental exposure to airborne mineral dusts (MD) and population health.
The prior lack of these studies may be related to the focus of early air pollution
regulations that were aimed at limiting mobile and industrial sourced pollutants.
Additionally, epidemiological study design requires amongst other criteria a large
population sample size (such as those found in urban areas) to demonstrate
association with health-related effects. Other factors that have hindered research
on MD include the following: long-established emphasis on occupational health
exposures, difficulty identifying etiological mechanisms responsible for disease
secondary to a complex matrix (i.e., dust may contain multiple components), lack of
sample and source characterization, and quantifying human exposures (Baxter et al.
2013 ).
This chapter provides an overview of the primary known or suspected adverse
health effects of, and related research on, mineral dusts. Research related to anthro-
pogenic and occupational exposures will also be discussed to provide perspective.

15.2 Review of Air Pollution Basics

Although interest and speculation regarding the potential health effects of exposure
to airborne “pollution” dates back to the fifteenth century (Gallo 2008 ), the expo-
sures examined were work related. Interest in community or population exposures
to air pollution is a somewhat recent development and few studies occurred prior
to the 1950s. Deterioration of air quality from centuries of industrial and urban
development prompted researchers to begin developing methods to study the health
effects of air pollution on communities. For example, to elucidate the scope and
burden of air pollution in the United States, several regulations were enacted,