FAQs (En)

Frequently Asked Questions

Find answers to your questions.

Why are airborne particles dangerous?

The smaller, the more dangerous. Fine particles PM2.5 of less than 2.5 microns - twenty times smaller than hair - can penetrate very deep in the lungs and for the smallest ones even invade the blood stream through the alveoli…

Fortunately, not all particles are dangerous. The larger ones, such as pollen, sand and most dusts are unpleasant and may sometimes cause allergies, but their health effects are limited.

However, a very specific category of particles, called PM2.5 also known as Fine Particles, which measure less than 2.5 microns (20 times smaller in diameter than a fine hair) are particularly harmful because their small size allows them to penetrate deeply into the respiratory tract. They contribute significantly to asthma and other major respiratory morbidities including Chronic Obstructive Pulmonary Disease, and potentially lung cancer even for non-smokers who have been over exposed to these particles.

The smallest of these particles measuring below 1 micron have even the capacity to cross the membrane separating the capillaries from the pulmonary alveoli. Once in the blood stream, where they remain for a long time, these particles can cause blood disease, strokes, major cardiac disorders and digestive cancers. They are also known to be responsible for foetal damage in pregnant women.