Filling the Indoor Air Quality Data Gap: Research Challenges and Opportunities

The rapid growth in the use of low-cost sensors for indoor air quality (IAQ) measurement campaigns, following the COVID-19 pandemic, has significantly improved public awareness of ventilation and IAQ in buildings. Yet, we still know very little about the level of pollutants in our indoor environments. Unlike outdoor air, IAQ is not routinely actively monitored and there are currently no widely accepted, standardised methodologies, procedures or regulations for doing so.  
No systematic long-term monitoring of IAQ in the UK or Ireland exists, despite recent calls to establish a large-scale programme akin to those already present in France and the US. The standard practice of short-term, sporadic measurements is not sufficient to determine total exposure or to quantify current levels of ventilation in the existing building stock. This information is vital to determine the effectiveness of current policy and to provide the basis for future decision making, such as pandemic preparation or building standards. 
Such a systematic, long-term UK monitoring programme or observatory would offer an unprecedented opportunity to quantify current ventilation and indoor pollution exposure, while providing data to establish the impact of changes to behaviour and policy over time, such as improved energy standards, higher internal temperatures and increasing levels of airtightness. However, before this can be achieved, key challenges must be addressed. A standardised, validated method of measuring and recording IAQ and building data is now essential to support the collation of large-scale datasets. An integrated approach to remote low-cost sensor-based monitoring would help maximise any future monitoring campaigns and ensure data is captured in the most effective way. Moreover, there is a real opportunity to capitalise on the significant increase in IAQ monitoring through the growth of consumer-oriented air pollution sensors and sensor-based ventilation control systems, to help fill the IAQ data gap.  
This paper presents a review of existing monitoring standards/guidance and available datasets to propose a roadmap to standardise the collection, storage and analysis of IAQ data for the purpose of evidencing the impact on health. This information will provide a useful resource for researchers and practitioners interested in measuring building performance and IAQ. Future research directions and opportunities are also discussed, with strategies presented on how to fill the IAQ data gap.