Since mask-wearing became mandatory in enclosed spaces in France, misleading claims have proliferated on social media like Facebook. One persistent myth suggests surgical masks are ineffective because their pores are too large to capture SARS-CoV-2. This is misinformation designed to discourage mask use.
Common fake news also raises fears of hypoxia or CO2 poisoning from masks, but many target their supposed ineffectiveness against the coronavirus. Following the July 20, 2020, mandate for masks in enclosed public spaces in France, posts highlighted pores allegedly too big for SARS-CoV-2.
Surgical masks feature pores around 0.3 microns (µm) to ensure breathability—smaller pores would hinder airflow. SARS-CoV-2 particles measure about 0.12 microns, so it's easy to assume the virus slips through. But is that the full story?
"Due to intermolecular forces like Van der Waals forces, tiny particles such as SARS-CoV-2 stick firmly to fibers upon contact. The dense network of non-woven fibers maximizes collision chances," explains French physicist Jean-Michel Courty in a Le Monde article from April 13, 2020.
Courty dismisses the pore-size argument outright. Beyond adhesion, viruses primarily travel in respiratory droplets measuring 5 to 15 microns in diameter. Health official Philippe Carenco adds that masks lose their electrostatic charge over time or when wet, underscoring the need to replace them regularly.
A May 2020 study by Hong Kong researchers, using hamsters in adjacent cages, demonstrated masks' effectiveness in reducing transmission from asymptomatic and pre-symptomatic carriers.
