July 2006
When the term “air pollution”
is uttered, it brings to mind
urban environments, replete
with car-packed freeways and belching
factories—not small villages and farmed
fields.
But rural areas are subject to local
sources of pollution as well as secondary
effects from urban areas—which
means the total global health burden
from air pollution falls largely on rural
populations, said Kirk Smith, professor
of environmental health sciences at UC
Berkeley’s School of Public Health.
Smith recently discussed the issue before
the United Nations Commission on
Sustainable Development, which monitors
progress toward goals set at the Earth
Summit of the U.N. held in 1992. Air pollution
was one of four subjects of focus at
the Commission’s recent meetings, which
also addressed energy, industrial development
and climate change.
Addressing the Commission in May,
Smith pointed out that in rural areas
worldwide, where little monitoring is
done for health assessments, there may
be a significant understatement of the
health impact of outdoor air pollution
and the benefit of control. Emissions inventories
done as part of climate and acid
precipitation programs show clearly that
rural areas can contribute substantially
to total emissions. In some areas, such
as China, total human exposure to outdoor
air pollutants in rural areas may be
up to 2.5 times the exposure that urban
residents face.
“Although it is not possible yet to extrapolate
globally,” said Smith, “it is clear
that the WHO estimate of 800,000 premature
deaths from urban air pollution is a
substantial underestimate of the total annual
impact of ambient air pollution from
both urban and rural environments.”
People living in rural areas face health
threats posed by three types of air pollution:
that generated in the home by using
simple, solid fuels for cooking and heat;“ambient” outdoor pollution from rural
and urban sources; and secondary pollutants,
which form when atmospheric
conditions trigger chemical reactions in
air emissions.
Half the world’s households—mostly in rural areas in developing
countries—use solid
fuels, such as coal or biomass,
for cooking and
heating. (Biomass refers
to any organic matter,
such as wood or agricultural
waste.)
The pollution caused
by such fuels has well-established
health effects:
chronic obstructive pulmonary
disease in adults
and pneumonia in children,
which together account
for nearly 10% of
all lost-life years worldwide,
said Smith. In addition,
lung cancer is
clearly shown to result from coal use and
possibly biomass smoke as well. Increasingly,
studies are also linking solid fuel
use to other cancers, as well as tuberculosis,
cataracts, low birth weight and possibly
heart disease.
Particularly in developing countries,
where rural population density and the
number of pollutant sources can exceed
that in cities, outdoor air is significantly
polluted—from surrounding cities, agricultural
burning, and industrial facilities
such as power plants and brick kilns.
The third source of pollution affecting
rural areas results from the transport
of emissions far from their primary emission
point—even continents away—and
their conversion into health hazards.
Some emissions such as hydrocarbons in
particular, that are themselves relatively
harmless, are converted to hazardous
ones by sunlight and interactions with
other pollutants.
Many efforts to address air pollution
have done little to alleviate its total impact.
Installing chimneys to vent smoke
from indoor stoves, for example, simply
moves the pollution a few feet away,
just adding to outdoor pollution. Moving
industries from urban to rural areas
similarly shifts the pollution from one environment
to another. Future efforts to
reduce the health eff ects of air pollution,
Smith argued, should consider a pollutant’s
total impact—in rural as well as urban
areas.
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Source: COEH Bridges
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