Speech Matters Too: New Evidence on Mask Effectiveness

The joint research by the HUN-REN Centre for Energy Research, the HUN-REN Wigner Research Centre for Physics, and Semmelweis University set out to determine the exact size and quantity of particles released into the air during speech, and how effectively different types of face masks filter them. The researchers combined the latest findings from environmental physics, aerosol science, and medicine. Secondary school students were actively involved in the work, playing a significant role in conducting the experiments and analysing the data.

The researchers studied 28 healthy volunteers in a specially designed enclosed measurement cabin, using a high-resolution particle spectrometer. The participants spoke both with and without a mask, while the exhaled particles were being measured.

The results show that the size distribution of exhaled submicron particles (smaller than 10⁻⁶ metres) followed a similar pattern for all participants, but the quantity emitted varied enormously between individuals — in some cases by a factor of up to one hundred. Speech volume had a major impact on the number of particles released: the louder a person spoke, the more particles were emitted into the air.

The study examined three commonly used face masks: FFP2, surgical, and two-layer cotton masks.

According to the results:

• FFP2 and surgical masks demonstrated excellent filtration performance under real-life conditions, even for the smallest particles (smaller than one micrometre), with an average efficiency of 80%.
• In contrast, cloth masks achieved an efficiency of only 50–60%, with their effectiveness strongly influenced by how well the mask fit the wearer’s face.

The study provides new evidence that properly worn surgical or FFP2 masks are not only effective when coughing or sneezing, but also significantly reduce the release of potentially infectious particles into the air during normal speech — a factor that may be particularly important in enclosed spaces or healthcare settings.

The message is clear: when worn correctly, a mask remains one of the most effective and simplest ways to prevent infections — especially in indoor settings and close-contact situations.

The findings of the Hungarian researchers have been published in Scientific Reports, a prestigious international journal in the Nature portfolio.