Update of the World Health Organization Global Air Quality Guidelines

Abstract

Introduction WHO Air Quality Guidelines (AQGs) are used as a reference tool to help decision-makers in setting standards and goals for air quality management. The last edition for ambient air quality was published in 2006 and included the classical air pollutants particulate matter (PM) ozone (O3), nitrogen dioxide (NO2) and sulfur dioxide (SO2). Since then, substantial new evidence on associations between short- and long-term exposure to these pollutants and health effects has become available. As such, WHO has recently started the update of the AQGs for ambient air pollutants. Methods The guideline development process is being carried out according to the WHO Handbook for Guideline Development, which is a manual to plan, develop and publish a WHO guideline free from biases that meets public health needs. Four expert groups with different skills, roles, responsibilities and specific tasks are to be established from an early stage of the process, including experienced methodologists involved to support translation of evidence into recommendations following the GRADE framework. Results Systematic reviews of the scientific evidence are planned to be conducted for PM and its major size fractions and components, O3, NO2, SO2 and carbon monoxide (CO). Results from these reviews will inform the need to change the existing guideline values, recommend guidelines for new pollutants (e.g. for black carbon) or for new averaging times (e.g. for long-term ozone exposure). The guidelines are also expected to review the available evidence concerning specific measures or interventions shown to decrease the levels of air pollutants and improve health. The process will have to scrutinize and address confounding due to multipollutant exposures. Conclusions The upcoming evidence reviews will serve as the basis to develop up-to-date evidence-based recommendations to continue protecting populations worldwide from the adverse health effects of air pollution.