SULFUR-DIOXIDE AND SUSPENDED PARTICULATE MATTER - WHERE DO WE STAND

Summarizing the more recent literature findings to reach a conclusion about the validity of the WHO long-term goals, there is little data on which a change of the goals or the criteria can be based. By taking a safety factor, the WHO goals are still somewhere in the no effect level, even though the tendency in the newer research data is to find effects at lower levels than ever before. This may be due to the fact that SO2 and particulates can only act as indicators, not explaining the real mechanism underlying the dose-effect relationships, e.g., through the presence of secondary pollutants like sulfates and sulfuric acid, or even through as yet unrecognized other mechanisms. This can not be used against the standard setting for SO2 and particulates, however, until a new mechanism is fully documented [Health effects are discussed.].