Characterising low-cost sensors in highly portable platforms to quantify personal exposure in diverse environments

The inaccurate quantification of personal exposureto air pollutionintroduces error and bias in health estimations, severely limiting causal inference in epidemiological researchworldwide. Rapid advancements in affordable, miniaturised air pollution sensor technologies offer the potential to address this limitation by capturing the high variability of personal exposureduring daily life in large-scale studies withunprecedentedspatial and temporal resolution.However,concerns remain regarding thesuitabilityof novel sensing technologies for scientific and policy purposes. In this paperwe characterise the 25performance of a portablepersonalair quality monitor (PAM) that integrates multiple miniaturised sensors fornitrogen oxides (NOx), carbon monoxide (CO), ozone (O3) and particulate matter (PM)measurementsalong with temperature, relative humidity, acceleration,noise and GPS sensors. Overall, the air pollution sensors showed excellent agreementwith standard instrumentation inoutdoor, indoor and commuting microenvironments across seasons and different geographical settings. Animportant outcome of this study is that the errorof the PAMis significantly smaller than the error introduced when estimating 30personal exposure based on sparsely distributed outdoor fixed monitoring stations. Hence, novel sensing technologies as the ones demonstrated here can revolutionise health studiesby providinghighly resolvedreliable exposure metrics at large scale to investigate the underlying mechanisms of the effects of air pollution on health