How useful are microsensors for measuring exposure to air pollution?

A strongly growing practice

Sensor systems, commonly known as microsensors, have been developing rapidly in recent years. They are used by individuals as well as by local authorities and associations wanting to raise public awareness of the issue of air pollution.

Installed indoors or outdoors or directly worn by individuals, these devices are mainly used to measure particulate matter (PM10 or PM2.5), carbon monoxide and volatile organic compounds. Since the pandemic, they have also been used to measure levels of carbon dioxide in public buildings, in order to determine when air renewal measures (increased aeration, ventilation, etc.) are necessary. 

Beneficial awareness-raising devices when combined with additional measures

These microsensors are able to identify potential sources of pollution and measure the concentration levels of pollutants to which individuals are exposed, whether at home, at work, or when travelling.

However, the information displayed by many of the microsensors on the market, in the form of a colour code for example, is based on heterogeneous and poorly documented criteria. Moreover, most of these microsensors, often referred to as “air quality microsensors”, are in practice only able to measure a single pollutant. They therefore only partially reflect the quality of the air we breathe.

 “Sensor systems are useful tools in terms of improving knowledge on pollution and good practices to be adopted. However, their use should be combined with additional measures to bring about lasting behaviour changes; these measures could include modifying travel habits, reducing emissions from certain sources of indoor pollution (cooking, chimney fires, etc.), and aerating. Moreover, the data obtained by these tools should be correctly interpreted: they do not reflect a potential risk to the health of individuals but rather indicate levels of exposure to certain air pollutants” specifies Emmanuelle Durand, coordinator of this expert appraisal at the Agency.

Tools that supplement air quality monitoring systems

These tools are capable of taking more measurements in time and space than the regulatory monitoring systems implemented by the approved air quality monitoring associations (AASQA).

However, even though efforts are being made by microsensor designers, the metrological quality of the data generated remains below that of the approved measurement stations.

Therefore, according to ANSES, in order to be used as part of scientific work or expert health risk assessments, the data from microsensors must meet a number of requirements dealing for example with the spatial-temporal representativeness of the measurements taken in relation to the objective at hand, or the description of the environments studied.

Data to enhance the multi-exposure approach

Sensor systems are particularly useful for acquiring information in places where exposure to air pollutants is currently poorly documented, for example in public buildings.

The Agency also underlines that the data from these tools can provide input for studies on environmental health and for those on the exposome, which corresponds to all the exposures of an individual in a lifetime.