The Balearic Islands have reported a surge in seasonal influenza cases, with incidence rates now at 75 per 100,000 people, exceeding the alert threshold of 36. Responding to this rise, the Conselleria de Salut has issued guidance encouraging the public to make use of face masks in healthcare facilities, enclosed public spaces, public transport, and other crowded environments in order to limit viral spread.
Yet health authorities are stressing that relying on outdated face masks could offer little real defence. "Masks come with an expiry date, and their protective ability diminishes over time. Using them past this limit might provide only a false sense of security."
The risks are particularly relevant as many individuals consider reusing masks stockpiled during the COVID-19 pandemic. Different mask types—such as FFP2 and standard surgical masks—have variable shelf lives, generally ranging from one to three years post-manufacture. For example, an FFP2 mask is typically effective for up to three years, while a surgical mask should not be relied on beyond one to two years.
How mask expiration impacts effectiveness
Expiry labels aren’t simply formalities: the performance of medical face masks declines as components age. The elasticated straps may lose tension, diminishing facial fit and allowing unfiltered air to bypass the mask. In FFP2 or similar masks, the foam around the nose may also harden or degrade, weakening the seal. Filter media—often electrostatically charged non-woven fibres—can lose their filtering ability over time or under poor storage conditions, such as excessive heat or humidity.
Visually, a mask's appearance can be deceiving. Degradation can occur even if the mask looks intact. Telltale signs include stretched or brittle rubber bands, visible discoloration, tears, separation between layers, a hardened or crumbling nose foam, or an off-putting odour. If any such symptoms are present or the printed expiry date has passed, the mask should be discarded: "A mask that is past its date, regardless of appearance, mustn’t be used as it may not meet essential safety standards."
Types of masks and their intended use
Not all masks serve the same purpose. Surgical masks provide source control, helping prevent transmission from the wearer to others by blocking respiratory droplets. Their filtration is largely one-way, and the fit is loose.
In contrast, filtering masks (e.g., FFP2, N95) protect both the wearer and those nearby, using multiple layers—including an electrostatic component—and a tighter facial seal to filter inhaled and exhaled air. Both categories depend on reliable fit and undamaged, active filtration media. Expiry or damage undermines both filtration and fit, exposing users to airborne pathogens and offering limited – if any – real-world protection.
Broader preventive measures for influenza
While masks remain a useful tool against airborne viruses, the annual flu vaccine continues to be the most effective measure for reducing serious complications. Routine vaccination is particularly important for at-risk individuals. Additional recommendations include regular hand washing with soap and water or using alcohol-based sanitisers, as flu viruses often survive on surfaces and can transfer through contact with facial mucosa.
Adopting good respiratory etiquette—covering coughs or sneezes with a bent elbow, not hands—and minimising unnecessary contact with nose, mouth, or eyes further reduces the risk of infection. Well-ventilated spaces and avoidance of crowded settings, where possible, remain valuable elements in public health strategy. Collectively, these actions support individual and community protection as cases climb in the Balearics.