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

INTRODUCTION
• Chapters 1 and 2 address the sources and emissions of the main pollutants
presented in the guidelines and discuss their ambient concentrations in various
parts of the world. Th is review demonstrates wide diversity of air quality
in the world, posing quite diff erent challenges to air quality management. In
many areas with high levels of pollution, it is caused by the use of obsolete
technologies and lack of pollution control systems. Pollution reduction is
technically feasible, but political or socioeconomic conditions and lack of
organizational capacity may limit the eff ectiveness of air quality management.
Poverty may be an obstacle in achieving improvements in air quality. In many
developed countries, air quality has already improved in the last few decades,
owing largely to air quality regulation. Further progress, necessary to reduce
the adverse health impacts of pollution observed even at those low levels,
requires the development and use of new technologies and, oft en, a change in
population lifestyle and the introduction of new approaches to urban development.
• Chapters 3–5 present important concepts and methods concerning the quantifi
cation of human exposure to air pollution and the assessment of its eff ects
on health. Factors that determine individual susceptibility to air pollution are
also reviewed.
• Chapter 6 discusses the issue of environmental equity, and documents the unequal
distribution of health risks due to air pollution both within and among
nations.
• Chapter 7 discusses methods for quantifying the health burden of air pollution
that trigger policy reactions, and may be used to analyse the cost–eff ectiveness
of various policy options.
• Chapter 8 discusses the use of the guidelines in developing air quality standards
and other policy tools.
• Chapter 9 focuses on indoor air pollution, especially on the conditions prevalent
in developing countries owing to the indoor combustion of solid fuels.
Owing to the magnitude of the health impacts of this pollution and the need
to use risk reduction approaches that possibly diff er from those developed for
urban air quality management, this chapter makes preliminary recommendations
for future WHO work on this specifi c problem.
• Chapters 10–13 comprise reviews of the health eff ects of PM, ozone, nitrogen
dioxide and sulfur dioxide, respectively. Health-based guidelines are presented
for each pollutant, based on those reviews, together with the rationale
for the decision to revise the guideline value or to retain the existing value.
As noted above, the epidemiological evidence indicates that the possibility of
adverse health eff ects remains even if the guideline value is achieved. For this
reason, some countries might decide to adopt lower concentrations than the
WHO guideline values as national air quality standards.
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