Greenhouse gas (GHG) pricing and mortality: evidence from a systematic review and meta-regression

According to the World Health Organization (WHO), the climate crisis constitutes the “greatest threat to global health in the 21st century”, the impacts of which are extremely unequally distributed. Economic activity associated with greenhouse gas (GHG) emissions results in air pollution mortality, among other consequences for ill-health. The air quality experienced by 99% of the global population does not meet WHO recommended standards. Thereby, air pollution is thought responsible for one in 14 deaths. Health co-benefits of climate mitigation generally and GHG pricing specifically are currently largely ignored in policy assessment and decision-making.

We present a systematic review and meta-regression of statistical modelling studies analysing how GHG pricing could change ambient air pollution mortality. We find a reduction of ambient air pollution mortality associated with GHG pricing and examine the variation in findings across contexts using meta-regression. However, there were various threats to validity in the studies – for example, they often lacked calibration using observational data – meaning that our confidence in the studies was not always high. More generally, there is a need for more transparent reporting, which could be facilitated by accepted reporting standards in the field. Our systematic searches identified a relative lack of studies in upper middle- and lower middle-income countries where air pollution is particularly high. Future studies examining the health effects of GHG pricing in these contexts are needed. As with other urgent public health crisis such as Covid-19, these need to be assessed based on currently available evidence.