Air quality is important for several reasons. For measuring it, smart micro-sensors are on the increase. However, this technique has stumbled at the lack of a common format for data exchange.

The composition of ambient air is a health and climate issue. The recent travel restrictions have brought the question of indoor air quality to the forefront. New technologies can provide some answers to the questions raised by this public health issue.
The general public is familiar with smart devices for measuring air quality in the home, such as the Netatmo weather station or the Temtop and Airthings monitors (Wave Plus). On top of carbon dioxide levels, they can analyze fine particles and chemicals in the air. On its website, startup IQAir, which offers professional versions of this type of equipment (AirVisual Enterprise), explains the improvements in wellbeing in the workplace and in productivity that can result from the control of air quality: “it has been proven that bad ventilation (high levels of carbon dioxide) changes cognitive ability and decision-making, and can cause headaches as well as fatigue”.
These measurement tools can be paired with professional air cleaners (NatéoSanté, JVD or Pureaéro, for example), the aim of which is to combat polluting particles, allergens, bacteria, and viruses.
As for the Flow sensor by Plume Labs, it offers to measure outdoor air quality and, depending on the ambient level of exposure to pollution, provide a real-time recommendation of a better itinerary to places where the air is purer. Via a crowdsourcing system similar to mobility applications such as Waze, this type of sensor gathers and consolidates data from voluntary contributors. Plume Labs are thus mapping atmospheric pollution across the globe.

Smart cities at the forefront

On the scale of a city or local community, air quality measurement can be one of the benefits of the smart city, with a real-time dimension. The city of Grenoble communicates on the air quality tracking system that has been set up in daycare centers and schools and publishes the monitoring results for each institution.

The city of Angers’ is to regulate urban traffic using real-time analysis of air quality and traffic.

Concerning the outdoors, Air Pays de Loire, part of the “Société d’aménagement de la métropole Ouest Atlantique“ (Samoa, the West Atlantic metropolis urban planning company), launched an experiment on the Island of Nantes in May 2022 that is to last for five months. A connected billboard for motorists live streams the air quality index – from good to extremely bad – and offers alternatives for using cars differently or for changing mode of transport. Another billboard is for cyclists. Depending on the air quality, it suggests one of three possible routes.
Presented as a world first, the city of Angers’ “5G Green Mobility” project, as press agency API explains, is to enable regulation of traffic in urban areas thanks to the real-time analysis of air quality and traffic.
With a budget of 4.8 million euros, over half of which comes from state subsidies in the scope of the France Relance program, this work brings together Toulouse startup WaltR, telecoms operator Alsatis, and the Nantes Lacroix group, an Internet of Things (IoT) specialist.
The system proposed calls upon “spectral cameras that detect and evaluate air pollution in high resolution and a private 5G microcell network that gathers data such as greenhouse gas emission rates or meteorological variables”. As for the IoT infrastructure, it tracks “data coming from vehicles, peaks in traffic, and the types of road signaling in place so as to offer micromanagement of road traffic in real time”.
The private 5G network for the Angers smart city is planned for the first half of 2022 . Integration of the first pollution measurement sensors is to follow in the summer and the platform should be up and running by the end of 2023.

Protocols and interoperability

The smart microsensors used by individuals, cities, or businesses have a downside. Due to a lack of shared protocols, they do not offer a single data format, which would make it possible to transform and aggregate this data as well as make these devices interoperable.
“Smart microsensors are not yet mature enough at the metrological level for them to be used for regulatory supervision”, says Pierre Pernot, communications manager of Airparif, a body approved by the public authorities for monitoring air quality in the Île-de-France region. “The results on air quality should not depend on the equipment.”
On the contrary, Airparif and other approved bodies use the same rules for data collection, storage, and aggregation. “Although we use various brands of sensor, we measure air quality in the same way in Dunkirk as in Paris.”
Airparif has roughly seventy measurement stations, of which around fifty are permanent. True static mini laboratories, they enable continuous measurement of a large number of pollutants. However, this automatic analysis is not possible for some of them, like polycyclic aromatic hydrocarbons (PAH). Collection is performed using a filter or diffusion tube for “posteriori” analysis in a laboratory.
In the case of automatic collection, the data is sent to the Airparif headquarters via a broadband link. “There are no volume or real-time dimension issues, which would require the use of 5G, Pierre Pernot states. If it was necessary to instantly compare data with large traffic streams, that would make sense.”
Collection takes place every hour except during pollution peaks when frequency is every quarter of an hour. The data are saved and put into a database. Before studying these data, the association ensures they are valid. “A technical operation on a station could cause incorrect measurement for example”. Airparif uses XR, the environmental data gathering, processing, and reporting software published by ENVEA.

A microsensor challenge

Despite their lack of interoperability, Pierre Pernot believes that smart microsensors constitute a tool for raising public awareness of the current stakes. “This reduces the distance between the citizen and public stakeholders.”
The game could evolve positively. In 2020, the French National Institute for Industrial Environment and Risks (Ineris) and the French National Laboratory of Metrology and Testing (LNE) created the CIE association (Instrumentation certification for the environment) so as to establish an Air Quality Sensor certification for sensor systems measuring outdoor air quality. A standard is also being developed at the European level.
In the meantime, Airparif is carrying out monitoring and technical integration work on market solutions. Via its Airlab Solutions cell, the association organizes a microsensor challenge every two years. It tests manufacturers’ devices in real conditions and publishes the results, highlighting the advantages and limits of each model. The next edition of this comparator will take place in 2023 in France and in Thailand.

The issue of data rendering

Beyond the question of interoperability, the processing of microsensor data poses two questions. Unlike permanent or semi-permanent stations, these sensors are ever more mobile. “It is therefore necessary to geolocate the data, work on trajectories, and use correction systems”, Pierre Pernot specifies. And what about the carbon footprint linked to data collection and storage if the number of smart measurement objects is to increase exponentially?
Finally, the last element to be considered: data rendering. Since 2018, Airparif has offered the data produced as open data for economic players and data scientists. For these data to be understandable by the general public they must, however, be formatted and contextualized (regulatory thresholds, limit values, history).
Thus put into perspective, the data can be published by the media and local authorities, in particular via billboards. On its website, Airparif provides a map of the pollution in the Île-de-France region, with a resolution of around 10 m for Paris, 25 m for the inner suburbs, and 50 m for the outer suburbs.
In France, on a national scale, Ineris publishes Geod’air online, an interactive map to track the real-time evolution of different pollutants (ozone, carbon monoxide, nitrogen dioxide, particulate matter, sulfur dioxide). As for Prev’Air, another Ineris website, this produces forecasts.

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