Air pollution trajectories and life expectancy in Nigeria

Purpose - The purpose of the study is to examine the relationship between air pollution and life expectancy considering the roles of institutional quality, agricultural output, foreign direct investment (FDI) and other socio-economic variables in Nigeria from 1981Q1 to 2019Q4. Design/methodology/approach - The study employed spliced quarterly data from annual series collected from the World Bank development indicators and Central Bank of Nigeria. The dynamic multivariate models were analysed using the vector error correction mechanism (VECM), variance decomposition and Granger causality techniques. Findings - The VECM result indicated a statistically significant adverse effect of air pollution on life expectancy. However, institutional quality, gross domestic product per capita, agricultural output, government social expenditure and school enrolment rate ameliorate the adverse health effects of air pollution, while FDI had mixed effects on life expectancy at different significance levels and at varying lag lengths. The Granger causality result revealed a uni-directional causality from air pollution to life expectancy; bidirectional causal chain between agriculture, FDI, government social expenditure and life expectancy, while a uni-directional causal linkage run from life expectancy to income per head and from school enrolment to life expectancy respectively. However, there is no evidence of causation between institutional quality and life expectancy due to weak institutional quality, but foreign direct invest causes carbon emission in a uni-directional manner in line with pollution haven hypothesis. Research limitations/implications - The study's modelling is limited by not considering the resource curse variable in the model due to paucity of data. Nigeria is the biggest crude oil exporter in Africa and ranks 13th globally with daily output of about 2.4 m barrels. Thus, the negation of resource curse in air pollution–life expectancy nexus de-emphasises the effectiveness of rich resources on health and environment. Future studies could address this limitation by incorporating resource curse in environmental-health models for Nigeria. Practical implications - It is imperative for the country to adopt stringent anti-air pollution strategies that would establish a balance between FDI attraction and agricultural expansion to the benefits of her citizens' longevity. Also, education should be considered as a strategic action to enhance life expectancy through expansion in the provision, accessibility and affordability to improved school enrolment rate. The choice of quarterly time series over annual data helped to establish the current relationship between air pollution and life expectancy using efficient estimators. Originality/value - The study contributes to literature by disaggregating yearly series into quarterly series, which has implications for the efficiency of the estimates, unlike earlier studies which ignored this fundamental process. The result of this study produced reliable policy direction for improvement in life expectancy in an emerging economy since quarterly estimates are more robust and reliable for forecasting than its yearly counterpart. The outcome of the study extended the original tenets of the Grossman's health stock theory using the environmental Kuznets curve (EKC) and pollution haven hypotheses (PHH).