Ammonium is one of the specific components of fine particulate matter (PM 2.5 ) that has been linked to a higher risk of death compared to other chemicals found in it, according to a new study in the journal Epidemiology . This finding stems from the largest global analysis of its kind, led by the London School of Hygiene & Tropical Medicine (LSHTM) as part of the Multi-City Multi-Country (MCC) Collaborative Research Network. We applied a two-stage analysis on data collected from 210 locations in 16 countries. In the first stage, we estimated location-specific relative risks (RR) for mortality associated with daily total PM2.5 through time series regression analysis. We then pooled these estimates in a meta-regression model that included city-specific log ratio-transformed proportions of seven PM 2.5 components as well as meta-predictors derived from city-specific socio-economic and environmental indicators. We found associations between RR and several PM 2.5 […]