Abstract
The impacts of fine particulate matter (PM(2.5)) air pollution on health outcomes, especially those of children, have attracted worldwide attention. Based on the PM(2.5) concentration data of 94 countries, including the least developed countries estimated by satellite observations in nearly 20 years, this paper investigated the impacts of PM(2.5) pollution on under-five mortality rate (U5MR) and analyzed the role of public service in moderating the PM(2.5)-mortality relationship. Results indicated that PM(2.5) pollution had significantly positive influence on U5MR globally. However, the effects of fine particulate pollution on child mortality were heterogeneous in terms of their significance and degrees in countries with different levels of development. A further test based on panel threshold model revealed that public service, measured by public education spending and sanitation service, played a positive moderating role in the PM(2.5)-mortality relationship. Specifically, when the ratio of public education expenditure in GDP of a country exceeded the first threshold value 3.39% and the second threshold value 5.47%, the magnitude of the impacts of PM(2.5) pollution on U5MR significantly decreased accordingly. When the percentage of population with access to improved sanitation facilities in a country was over 41.3%, the health damaging effects were reduced by more than half. This paper fills the current gap of PM(2.5) research in least developed countries and provides key policy recommendations.