Humidity and lack of ventilation: the under-considered scourge of mold in homes

Julien M. has just become the father of his second child. Before the arrival of his little girl, he cleaned the mold that regularly appears in the master bedroom of his apartment, in Marly-le-Roi (Yvelines). He also applied an anti-mold treatment and repainted the ceiling.

"But the mold reappeared barely ten days later," he explained to Maxime Gay, director of a Murprotec agency specializing in the treatment of humidity and indoor air pollution, who came to carry out a humidity diagnosis.

Julien M. was "worried" about this mold and wanted to "know if the humidity could pose a problem for the children."

And he was right to be afraid. "Humidity mold creates aspergillus," a fungus that can cause allergies and respiratory problems if it contaminates the lungs, Maxime Gay explains to the family.

Indoor air is five to eight times more polluted than outdoor air according to estimates from the Indoor Environment Quality Observatory (OQEI).

The subject of indoor air quality "has been understudied, despite its importance in our lives", since the French spend 80% of their time in enclosed spaces (housing, work, transport), estimates Margaux Sanchez, specialist in air risk assessment at the National Agency for Food, Agriculture and Food Safety (Anses).

20.000 premature deaths per year

Humidity is not the only factor in poor indoor air quality, which can be degraded by several types of chemical, physical pollutants - such as asbestos - or biological, such as pollen or dust mites.

These pollutions can come from outside, from the materials used to construct the building, but especially from behavior: tobacco smoke, use of candles and incense, cleaning with harmful products.

In 2014, ANSES estimated that the number of premature deaths caused by the six main indoor air pollutants was nearly 20.000 per year. Each year, there are more than 31.000 new cases.

The Murprotec company has launched prevention actions, including a study carried out with the Santé Réspiratoire France association among 310 people suffering from chronic respiratory diseases or their caregivers.

Among them, 43% said they had already lived in a home with traces of damp and a majority were not aware of the health dangers.

"Mold is bad for respiratory health, it can trigger asthma attacks, headaches, respiratory discomfort, olfactory discomfort," warns Margaux Sanchez.

Better insulated but less ventilated

Mold can also threaten a house. In Rodolphe Muller's basement in Colombes (Hauts-de-Seine), mineral salts are gradually eating away at the walls. They come from the humidity of the earth surrounding the foundations of the house, "poorly protected" according to diagnostician Maxime Gay, after analyzing the humidity of the walls and the type of mold present.

He notes that "people often look the other way when they have mold and don't deal with it," but by eating away at "the binders in the wall," the mineral salts weaken the solidity of the building.

For Mr Muller, the best solution will be to improve the waterproofing of the foundations of his house, while for the family in Marly-le-Roi, better ventilation is necessary.

"The ventilation system - a simple VMC - is undersized for your home, which is well insulated, with double-glazed windows," Mr. Gay explains to them.

More efficient ventilation systems can be installed but will require the opinion of the general meeting of co-owners of the couple's residence.

"In the meantime, ventilate as much as possible, dry laundry outside and clean mold with white vinegar as soon as it appears," recommends the specialist.

The ANSES recommendation is to "ventilate for at least 10 minutes per day" by creating a draft, reports Margaux Sanchez. For recent homes, better insulated for energy reasons, but not necessarily better ventilated, these ten minutes sometimes prove insufficient.

Illustrative image of the article via Depositphotos.com.