The update of World Health Organization air quality guidelines and its implications on health risk management in low- and middle-income countries

1.Introduction As one of the milestone documents on global air quality manage-ment,the World Health Organization(WHO)health guidelines have been periodically adopted and published air quality guidelines(AQGs)following systematic reviews on evidence from medical and public health studies,and through extensive expert panel discussion and con-sultation.Since 1987,WHO has periodically issued health-based air quality guidelines-Air Quality Guidelines for Europe(hereafter referred to as"AQGs(1987)")to assist governments and civil society to reduce human exposure to air pollution and its adverse effects.