Face masks available to consumers in China for protection against air pollution vary widely in their real-world performance, suggests a recent study. Although a mask may filter tiny particles as advertised, researchers report in Occupational & Environmental Medicine said that face size and shape as well as movement can lead to leakage as high as 68 percent. Senior study author Miranda Loh, an exposure and environmental scientist at the Institute of Occupational Medicine in Edinburgh, Scotland said: “Even if the filtration efficiency of the mask is high, and the mask fits the person initially, the mask may not continue to give a good fit as the person goes about their daily activities.” “It is important for people to understand that not all masks are effective at reducing exposure to particles in air pollution. And none of these masks reduced the concentration of pollution gases such as nitrogen dioxide,” she added in an email. The study team conducted an assessment of a sampling of masks in Beijing is part of a larger project funded by the Research Councils UK, examining air pollution in the Chinese capital and its health effects. Air pollution causes an estimated 1.6 million premature deaths in China each year, the study team notes. These tiny particles found in vehicle exhaust and industrial emissions and known as “PM2.5” can penetrate deep into the lungs, and from there, enter the bloodstream. Tests made on nine different mask types showed that the average particle and carbon penetration ranged from 0.26 percent to 26 percent, depending on the mask material. Richard Peltier of the University of Massachusetts, who wasn’t involved in the study, told Reuters Health by email: “Air pollution is a global problem that is important for not only Beijing, but also Boston and Barcelona. Breathing pollutants, especially particulate matter, is very harmful, causing millions of early deaths across the world.” “Future studies should recruit more volunteers, and focus on the main reasons why masks seem to fail - whether the material itself is faulty, the masks don’t fit different people well, or they don’t seem to work well for daily living conditions,” Peltier added.