Table 1 summarizes key reference standards and
guidelines for ambient SO2 concentrations.
Recommendations
In the long term, countries should seek to ensure
that ambient exposure to sulfur dioxide does not
exceed the guidelines recommended by WHO.
In the interim, countries should set ambient standards
for sulfur dioxide that take into account
the benefits to human health and sensitive ecosystems
of reducing exposure to sulfur dioxide;
the concentration levels achievable by pollution
prevention and control measures; and the costs
involved in meeting the standards. In adopting
new ambient air quality standards or guidelines,
countries should set appropriate phasein
periods. Where large differences exist between
the costs and the benefits of meeting air quality
standards and guidelines, it may be appropriate
to establish area-specific ambient standards case
by case.
Prior to carrying out an environmental assessment
(EA), a trigger value for the annual average
concentrations of sulfur dioxide should be
agreed on by the country and the World Bank.
Countries may wish to adopt EU, USEPA, or WHO