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

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AIR QUALITY GUIDELINES
role, adopted and enforced by regulatory authorities, is to define the level of acceptable
air pollution for a country or region.
The primary aim of the guidelines presented here is to provide a uniform basis
for protecting public health from the effects of air pollution. However, these
guidelines have the character of recommendations, and it is not intended or suggested
that they simply be adopted as standards. As presented in Part 2, the epidemiological
evidence indicates that the possibility of adverse effects remains even
if the guideline value is achieved, and some countries may select even lower levels
for their standards. This chapter discusses some of the factors that should be evaluated
when moving from guidelines to standard setting and policy formulation.
In addition to the pathophysiological basis for the adverse effects that may be
associated with exposure to air pollution, these factors include current exposure
levels and risk perceptions of a given population, and, of equal importance, the
specific social, economic and cultural conditions encountered in a given location.
Provisions designed to protect vulnerable groups, such as young children or
the elderly, can also influence the stringency of air quality standards. In addition,
the standard-setting procedure may be influenced by the feasibility and costs of
implementing and enforcing the standards. These considerations may lead to
a standard above or below the respective recommended guideline value (1), as
can be observed from the air quality standards of countries around the world
included in Table 1.
Setting air quality standards
Air quality standards are considered to be the acceptable levels of air pollution,
in terms of potential impacts on public health and the environment, that are
Table 1. Selected air quality guidelines and standards
Source
WHO (2)
European Union (3)
United States (4)
California (5)
Japan (6)
Brazil (7)
Mexico (8)
South Africa (9)
India (10) (sensitive populations/residential/industrial)
China (11) (Classes I/II/III) d
1 year
Sulfur dioxide (μg/m3 )
24 hours
1 hour
a Not to be exceeded more than 3 days per year.
b Not to be exceeded more than 35 days per year.
c Photochemical oxidants.
d Class I: tourist, historical and conservation areas; Class II: residential urban and rural areas; Class III: industrial and heavy traffic areas.
78
80
78
50
15/60/80
20/60/100
20
125
366
105 c
105
365
341
125
30/80/120
50/150/250
350
655
262
150/500/700
10 minutes
500
500