Indoor Air Pollution Network

Designing future indoor air measurement campaigns

INDAIRPOLLNET (INDoor AIR POLLution NETwork: https://indairpollnet.eu/) is a European COST Action of more than 200 scientists. Through this network, we have defined the knowledge gaps and challenges for indoor air, highlighted the processes and pollutants that should be evaluated, the instruments that should be used to do so and the building parameters that must be considered. Based on our work, this document provides pointers for future indoor air measurements. This section focuses on some general pointers, with our more detailed recommendations being available through the 'Measurement Recommendations' section.

General overview

• Most studies to date have been short-term or in limited locations. Further, within study locations, measurements are often limited to one room/sampling point. Many of the issues we highlight would benefit from longer-term studies in a wider range of locations, both within and between buildings. In particular, the role of energy efficiency measures on indoor air quality (IAQ) needs quantification.

• Our work has shown that direct comparison of indoor air pollutant (IAP) concentrations is challenging as previous research has been conducted over different time periods, using different instruments and sampling techniques, and in different indoor environments. We recommend that future scientific studies be conducted following standardised procedures, which will allow for easier intercomparisons between studies in the future. 

• INDAIRPOLLNET includes indoor and outdoor air quality scientists. There is much the two communities can learn from each other and we recommend referring to relevant research by the outdoor air community before planning indoor measurements (and to our WG2 reports).

• Studies of IAQ also need to consider the impact of building parameters such as ventilation rate, lighting, temperature and humidity. These can all affect IAQ and indoor measurements can only be partially understood without measurements of these parameters.

• Our work has also highlighted the importance of the occupant on IAQ. An empty building will experience a different IAQ to an occupied building, all other things being equal. Such differences must be considered when trying to understand the IAQ in a specific building.

• Changes in lifestyle and materials used indoors, lead to changes in the composition of IAPs. We need to be mindful of emerging pollutants that may become an issue in the future.

• We note the importance of considering thermal, visual and acoustic comfort aspects as well as pollutant concentrations. Within this context, the consideration of subjective characteristics like physiological, social, or aesthetic building parameters becomes a priority.

• There is the potential for new modes of data collection (and analysis, e.g. machine learning) to significantly move this field forwards. Wearable devices that embed sensors for environmental parameters, cardio and respiratory signals of users, as well as chemical and biological pollution concentrations could be used to provide a wealth of citizen data.

• We believe that a network of well characterised test facilities (c.f. EUROCHAMP) with a minimum set of controlled variables in conjunction with a coupled indoor chemistry/dynamics model framework, could enable the study of many of these questions.

Health considerations

The main focus for INDAIRPOLLNET was to consider the chemical processing indoors. However, the endpoint for most of the work is that we want to better understand the chemical processing, so we can identify which pollutants are formed through different processes and hence highlight the potential implications for health. In the course of our work, we have identified the following objectives related to health that we believe would make excellent topics for future research, but require large toxicological or epidemiological approaches that are out of the scope of this project. We list them for those working in the fields of health science around air pollution. They are:

• What are the health implications of exposure to primary SVOCs and their reaction products?

• Do typical indoor levels of MVOC have a significant impact on occupant health? 

• How does IAQ affect cognition and for different target groups (e.g. toddlers, students, the elderly)?

• How does IAQ affect health in classrooms, particularly in the seasons with high incidences of respiratory diseases.

• How does IAQ impact the sick in hospitals?

• How does the IAQ in sports facilities impact on health, given there is higher pulmonary ventilation when exercising, so inhaled dose needs to be understood rather than just concentrations?

• Are biological or chemical pollutants worse for human health and under which conditions?

Microbial activity indoors

For similar reasons to above, we decided not to focus on numerous questions around microbiological processes indoors, but highlight the following topics that are ripe for future study:

• What is the relative VOC load from microbial activity in a “normal” versus “problem” dwelling?

• Do MVOC species indoors affect indoor air chemistry? 

• Does the microbial processing of widely used building materials result in significant levels of volatile emissions? 

• What is the balance between the building biome versus the occupant biome on the chemistry of indoor environments? 

• What role do biofragments, PM, surfaces and human activities play as microbial carriers?