Theme II - Air Pollution and Health
Substantial evidence links air pollution to health impacts at concentrations commonly encountered in the UK. Data is robust for the impacts of fine particulate matter (PM2.5) on cardiorespiratory diseases, but emerging evidence has demonstrated associations with adverse birth outcomes, sub-optimal developmental trajectories in children, the early aetiology of disease, impacts on mental health and dementia. If these observations can be shown to be robust and underpinned by causal pathways, they imply a substantial additional burden on the population's health, experienced across the life course. Addressing the evidence of the impact of air pollution on these emerging areas is the key aim of Theme II. We will do this by understanding the totality of air pollution exposures across the indoor to outdoor continuum in collaboration with themes I and III.
Theme II Projects
Project outline: Evidence on the impacts of air pollution on birth outcomes is accumulating, but results are inconclusive. Existing meta-analyses are now out of date, often of poor quality and the literature base has expanded rapidly in recent years. An updated meta-analysis addressing this area is urgently required.
Project outline: The impact of air pollution on dementia incidence has been identified as a priority area of research by COMEAP (Committee on the Medical Effects of Air Pollutants) and others. There is a need to understand the impact of long-term exposures and the underlying causal mechanisms of dementia risk. Impacts on early life cognitive development and mental health into adulthood have also been highlighted. Here we plan to address how air pollution mitigation measures impact on neurological endpoints, either reflecting planned interventions, such as London’s Ultra Low Emission Zone (ULEZ), or unplanned natural experiments, such as the impact of COVID-19 pandemic lockdown on air quality.
Project outline: Indoor air exposure models for studies of population health effects have been developed which include built environment characteristics, analysis of exposure measurement error, and measures of population movements (time activity patterns and population estimates). We will develop an integrated exposure model based on the above elements, for indoor air pollutants, namely CO and emerging chemicals (VOCs). The application of such models can be validated with measurements and then applied to epidemiological analyses, building on previous CO work. As this project is dependent on outputs from other projects underway, notably Theme I Project 6, activities in the first two years will focus on preparation and review of existing resources, with fieldwork and analysis following in Years 3-5
Project outline: This project will quantify exposures to primary particulate matter (from vehicular combustion and abrasion processes) and co-pollutant gases in transport microenvironments and assess their impact on health and acute adverse biological responses. It will initiate work investigating the acute effects of air pollution on the London Underground in sensitive sub-populations, as well as expand on previous personal monitoring studies highlighting the high exposures to diesel fumes experienced by professional drivers.
Project outline: Effects of NO2 and PM2.5 are difficult to disentangle but in recent years, with the introduction of particle traps, the ratio of NO2 and PM2.5 has been changing. If the associations for NO2 are an indicator for particulate matter, rather than a direct effect, the changing ratio should lead to a change in the time-series coefficient for NO2. The ratios with PM2.5 components may also have changed in different ways e.g. ultrafine particles dropped sharply with lowering sulphur content in fuel. This project complements the project on comparative toxicological potency of NO2 and PM in Theme III and extends previous HPRU work on measurement error and multi-pollutant models for NO2 and PM2.5. This project will dovetail with Theme III project 5 which is undertaking a similar project with laboratory based studies