INdoor Home Air Level Exploration (INHALE) Study: Protocol to Monitor Indoor Pollution in British Dwellings.

Knowledge on indoor air pollution exposure is limited. Collecting high-quality measurements in home environments is challenging, owing to the complexity of sampling options, the cost and limiting disturbance to occupants. The protocol developed for the INdoor Home Air Level Exploration (INHALE) study is designed to balance these factors by sampling indoor pollution as comprehensively as possible for a single week in the living room using non-obtrusive low-moderate cost sampling devices that are issued with easy-to-follow instructions, minimising the need for researcher visits. Indoor air pollutants included in the INHALE study were selected owing to their potential impacts on human health; these include volatile organic compounds, fungal spores, fine particulate matter, nitrogen oxides and ozone. Relevant indoor factors will also be monitored, such as temperature, relative humidity and carbon dioxide, as a proxy for ventilation, while questionnaires collect relevant information on local environment, building characteristics and participant activities, culture and social and economic status. The protocol for the INHALE study is suitable for exposure, epidemiology and intervention studies. It contributes to the development of standardised indoor sampling protocols that can be used at scale.