Air Quality Guidelines Global Update 2005 - World Health ...

ENVIRONMENTAL EQUITY
a lower SEP (and as a result have higher baseline mortality rates and steeper C–R
functions) the potential benefits of the diesel policy vis-à-vis mortality would be
substantially larger.
One goal of this chapter is to review findings from the air pollution and health
literature to identify the strength of current evidence for differential exposures
and health effects for people of different SEP. Several other important issues in
health impact assessment for PM that may have implications for environmental
equity are not directly dealt with. One is whether the C–R function differs for
different PM components and/or sources. Another is the possibility that the PM
C–R function has a different slope at concentrations well above those observed
in the current epidemiological literature, most of which has been based on data
from cities in the developed world.
Evidence of inequities in health effects of air pollution
It has been widely noted that persons of lower SEP have generally poorer health
status than more advantaged persons (26–28). Explanations for these differentials
have usually focused on factors such as limited access to high-quality health
care, inadequate nutrition, psychosocial stress, poor-quality drinking-water, alcohol
misuse, exposure to indoor pollution, smoking and exposure to factors at
the workplace (29–31). Link & Phelan (26) draw attention to a broader set of
contextual factors, including limited knowledge, money, power, prestige and
beneficial social connections, which together serve to reduce the poor people’s
ability to manage their own health risks (26). The relationship between low SEP
and ill-health is relevant to the issue of environmental equity, because susceptibility
to the health effects of air pollution may be greater among those with an
already compromised health status. Indeed, there is substantial epidemiological
support for this notion, going back to the distribution of health responses during
the London Fog of 1952 (32). If sick people are more responsive to air pollution
(i.e. higher relative risk per unit increase in exposure) and poor people are
more likely to be sick, then it would follow that poor people are on average more
responsive to a given concentration of air pollution than more economically advantaged
persons. It should be noted that, even if relative risks are constant, absolute
impacts of air pollution will be elevated in populations with a higher baseline
prevalence of mortality or morbidity.
Respiratory and cardiovascular diseases are especially relevant to air pollution
susceptibility. In developing countries, acute respiratory illnesses (ARI) are the
major cause of illness and death among children under five years of age (33) and
the burden is likely to be greater for groups with lower SEP within those countries
(34). Romieu and colleagues (33) note that “ARI is the most common cause
of illness and death in children in the developing world” and is responsible for
3–5 million deaths annually among children under five years of age. Indoor air
pollution from biomass combustion is thought to contribute to this burden of
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