Warner is working at the IRAS on a PhD project titled: The epidemiological analysis of pneumonia and COPD around livestock farms. His work consists of analyzing the data gathered for the Livestock Farming and Neighbouring Residents’ Health Study (the Dutch Veehouderij en Gezondheid Omwonenden (VGO) Study). His main focus is on investigating associations between lung function, air pollution and the microbiota of the upper respiratory tract.