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Monitoring air quality in and around Paris

When it comes to measuring air pollution, the weather is as important for Airparif as prevailing traffic conditions: anticyclones, lack of wind, temperature inversions, etc. Throughout the year, the organization measures air quality in Paris and its region and issues alerts when pollution spikes are expected, which in turn helps public policymakers take the necessary measures.

Measurement stations

A large but otherwise innocuous green box sits near the ring road around Paris. There are some sixty others throughout the Ile-de-France region. These are the Airparif stations in which air quality is measured. How do they work? On the roof of each station, automatic analyzers suck in air using a pump. The concentration of pollutants contained in this air is directly estimated by an automated scanner before the data is transmitted remotely, several times a day, to Airparif’s central computer before being stored in databases.

Station maintenance

At Airparif's headquarters, the laboratory is located at the entrance, so it is impossible to miss. Behind the bay window that separates it from the lobby, one sees computer screens that scroll through the data, multiple scientific instruments, and Air Liquide's ALPHAGAZ™ calibration gas canisters. 

As Laurent Gauvin, an Airparif metrologist, explains: "These gases ensure the proper calibration of the station’s equipment. Calibration gases are used to verify that an instrument is always accurate. If it is not, we readjust it". The stations are automated, but their maintenance requires regular visits from technicians, who are equipped with canisters of gas supplied by Air Liquide.

The ALPHAGAZ™ calibration gases supplied by Air Liquide allows to verify the precision of the equipment

Processing data in the laboratory

It's the same ritual every day. Once the data is sent from the station to the laboratory, Laurent Gauvin can begin his forecasts and then make them available on the Airparif website. There, on the big screen, he reads the results: "Today is okay, we are not exceeding 50 μg / m³ ". This represents 50 micrograms of particles per cubic meter of air.
If this threshold is exceeded, the alert is issued and the city can take measures designed to reduce the level of pollution: prohibiting some cars from circulating in the city, free parking for local residents, or lower fares for mass transit.

Focus on

PEMS: the stations of tomorrow with Air Liquide innovation

In addition to static measurement stations, tomorrow, there will be PEMS (for Portable Emission Measuring System). These compact analyzers have the advantage to work in real traffic conditions.

Read more

It’s with these PEMS that Airparif and Île-de-France Mobilités (formerly STIF, the regional transit authority) launched the world’s first emission measurement study. Some 22 buses, diesel and hybrid, will be equipped with PEMS until 2019. The goal is to measure exhaust levels (NOx, carbon monoxide, carbon dioxide...), which is a world first according to the organization. The ultimate objective of this study is to reduce the emissions of the buses in circulation as much as possible.

Air Liquide has innovated to offer gas adapted to these new mobile stations. Alexandre Mazars, Marketing Design Manager at Air Liquide: "Before, for the calibration of the PEMS, our clients needed multiple cylinders and equipments that were not easy to use. We have conceived a ready-to-use calibration kit that includes a cylinder that covers all searched pollutants in one. This makes life easier for our clients as it reduces the calibration time. The major challenge was technical, since nitric oxide and carbon dioxide molecules are known to be unstable once mixed. Still, our experts at Air Liquide managed to create and stabilize this mixture."


Airparif’s missions

Since its inception in 1979, and the Laure Law, which "recognizes the right of everyone to breathe air that does not harm health," informing the general public has been one of Airparif's central missions. "Monitor, understand, and support,” says Charlotte Songeur, Airparif's communications engineer. Analysis, forecasting, and impact measures but also education and awareness raising. And it works: "For 15 years, we've been seeing an improvement in air quality. Every pollutant has decreased except ozone. Between 2002 and 2012, pollution decreased by 30%."

Airlab, a responsible initiative
Companies (including Air Liquide), start-ups, associations and other organizations come together at Airlab to guarantee better air quality. Airparif is the initiator of this project, which was launched in September of 2017. "When we launched, we had about twenty partners. In less than a year, we have 60 partners," explains Thomas Alcaraz, who is responsible for the initiative at Airparif. Each company provides equipment and is making a financial contribution. But what exactly does the Airlab do? "This might involve, for example, the real-time monitoring of the air quality of a building, which is a project conducted by Veolia and Icade that will be operational in October 2018. The goal is to gradually improve the working conditions of employees." A project that could not have happened without Airlab.

Article published on September 25, 2018