The US government's Centers for Disease Control and Prevention (CDC) has issued an interim statement that advises people about using facemasks and respirators in public places (as opposed to workplaces) in the event of a pandemic. The advice is temporary, pending a fuller scientific investigation of the effectiveness of facemasks and respirators. The CDC is part of the US Department of Health and Human Services (HHS). The main concern is to tell people about facemasks and respirators, address their frequently asked questions, and give advice on additional precautions. However, at present, this advice is based on sparse scientific evidence, gleaned mostly from using these devices in healthcare settings. During a pandemic, facemasks and respirators on their own are unlikely to protect people from becoming infected or reduce the spread of the virus. Spread and infection are more likely to be contained if people also: -- Stay away from infected people, -- Avoid crowds, -- Stay home if they are infected, -- Wash hands frequently with soap and clean water, -- Take antiviral medication, -- Encourage family members and friends to stay at home if they are infected. CDC Director, Dr Julie Gerberding said: "During an influenza pandemic, we know that no single action will provide complete protection." She also said that many people will probably choose to use facemasks for extra protection even though there is little evidence of their effectiveness. "If people are not able to avoid crowded places, large gatherings or are caring for people who are ill, using a facemask or a respirator correctly and consistently could help protect people and reduce the spread of pandemic influenza," added Dr Gerberding. In summary, the guide suggests that you should consider wearing a facemask in a flu pandemic if you: -- Are sick with flu and close to people who may become infected (roughly within 6 feet, or about 2 metres). -- Live with or spend time with people who have flu symptoms (they could be infectious). -- Spend time in crowded places (to protect yourself from infected people, or if you are infected, to protect them from you). And you should consider using a respirator if you: -- Are well and spend time close to people who are infected (within 6 feet or 2 metres). -- Are taking care of a person who is sick with flu. The CDC emphasizes that whether you wear a mask, respirator, or neither of these, you should limit the time you spend close to infected people if you are well, and if you are infected yourself, limit the time you spend close to others to minimize the chance of passing it on. Facemasks are designed as a barrier to droplets from sneezes, coughs and splutters from other people. They also reduce the chance that the wearer will spray droplets onto others. They will not protect the wearer from breathing in small virus particles. Respirators on the other hand have finer filters designed to stop most virus particles from being breathed in by the wearer and are probably your best bet if you are in frequent contact with an infected person. Dr Michael Bell, associate director for infection control at CDC's Division of Healthcare Quality Promotion, put it like this: "If you're caring for someone who is ill with pandemic flu, proper use of a well-fitted respirator may be a reasonable choice." However, wearing facemasks and respirators brings additional problems not present when you don't wear them. For example they make you sweat and feel hot, and this increases the frequency of touching your face with your hands, adding an additional entry route for the virus. And they may also give you a false sense of security so you neglect other important precautions. US Health Secretary Mike Leavitt said pandemic flu remains a real threat and this guidance is an important step in the effort to ready the nation for such an event.