Inventory of the lead pollution produced by the fire at Notre Dame de Paris


More than a year after the fire at Notre-Dame de Paris, the official report on environmental pollution by lead is still not available. A team from Columbia University published, in June 2020, the only available study on pollution levels after the fire.

What are the levels of pollution observed around Notre-Dame de Paris?

Columbia researchers collected soil and dust samples distributed in concentric circles and under the plume of smoke. They then analyzed the lead content with an X-ray fluorescence detector.

The results obtained are expressed in mg/kg (milligram of lead per kilogram of sample) and are directly comparable with the health threshold of 300 mg/kg applicable in the European Union.

The results show contamination levels between 30 and 9000 mg/kg. The average value measured was 400 mg/kg and one sample out of 2 contained less than 140 mg/kg of lead (median value). This shows that there are many areas much more polluted than others.

Of the 100 samples analyzed, 29 samples had a concentration above the reference threshold of 300 mg/kg, 21 of which were located under the smoke plume of the fire.

In general, the areas under the plume had a higher concentration than those outside the plume.

The most contaminated samples (> 2000 mg/kg) were located both near the cathedral and below the fire plume.

These observations were also confirmed by another study looking at the lead content of honey produced in Paris.

What is the value of the Columbia University study?

The study was carried out by a university whose seriousness is world-renowned. Nevertheless, the sampling methodology leaves something to be desired.

Indeed, the use of metal equipment (spoons and sieves) presents a possible risk of contamination of the samples.

However, all the samples were taken according to the same protocol and with the same equipment.

So if contamination has occurred, it will be almost the same in all samples and does not impact the conclusions of the comparisons presented in the study.

Dust sampling with an adapted material (plastic) would have avoided these questions.

What are the risks of frequenting lead-contaminated areas?

Lead is a toxic metal that accumulates in the body and is eliminated very slowly. It is a toxic element with no threshold and it is essential to avoid and limit all exposure.

Going to a place where the soil or dust contains more than 300 mg/kg of lead significantly exposes organisms.

Outdoor environmental pollution diffuses and accumulates inside buildings in lead-polluted areas. For example, lead will attach itself to the soles of shoes and the pollution will be transported to the workplace as well as to homes.

Since we spend 80% of our time in buildings, it is important to monitor the level of ambient lead pollution to assess whether the health reference threshold is being exceeded.

Have the public authorities become aware of the extent of this lead pollution?

INERIS had demonstrated in November 2019 that the cloud of smoke had transported lead at least 50 kilometers from Paris in a westerly direction, passing through the 6th, 7th, 8th, 15th, 16th and 17th districts of Paris and then on to cities such as Neuilly, Puteaux, Suresnes, Orgeval, Rueil Malmaison, Saint Cloud, Saint germain-en-laye, Mantes la Jolie, Limay...

This official INERIS study confirmed the map published by YOOTEST in June 2019 and should have alerted the authorities of the health risks for the populations.

The Paris City Hall was seriously questioned by Mediapart which denounced the sampling methods (wipes) and the manipulation of results in order to avoid having to close schools.

To our knowledge, no municipality has carried out a large-scale campaign with dust sampling to measure the reality of pollution.  Although YOOTEST was contacted by the technical services of several cities concerned to provide analysis kits, the political green light was never given.

Today, the Columbia University study clearly highlights the lead pollution linked to the Notre-Dame fire and one can question the position of the authorities.

If you want to know if your home or office has a dangerous level of lead pollution, it is up to you to take the measurement!

How to measure lead pollution in a building?

Dust analysis is used to measure the lead pollution of a home or office. The analysis kit YOOTEST Lead allows you to take a sample easily with a vacuum cleaner, including the transport of the sample and benefits from the reliability of a laboratory analysis. The results are presented in an interpreted and understandable report.



Lead Pollution Test

Indoor air quality diagnosis to measure the pollution of the indoor environment by Lead. Test with laboratory analysis. Order your Test




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