One of the most important tools in the prevention and spread of an influenza pandemic is the use of protective masks. The Centers for Disease Control and Prevention (CDC) and the Occupational Safety and Health Administration (OSHA) have guidelines for the different types of masks.

Facemasks are loose fitting disposable masks that cover the nose and mouth and are commonly used to prevent the spread of infection during surgical, dental and medical procedures. These masks are also used in isolation. These Facemasks help to prevent spread to and by the person wearing the mask by stopping droplets from being spread by the person wearing them. They also keep splashes or sprays from reaching the mouth and nose of the person wearing the facemask. They are not designed to protect you against breathing in very small particles. Face Masks should be used once and then they should be discarded.

The US department of Labor recommends air-purifying respirators as a program for workers involved directly with influenza infected patients or birds. This is part of a comprehensive respiratory protection program. As part of the recommendation is air-purifying respirators such as N95.

n95 mask have advantages of typical cloth or surgical masks. They are greater than 95% effective at filtering .3 -┬Ám particles. A typical droplet generated during coughing, sneezing and talking is 5 -um, which is significantly larger thus preventing it from passing through the filter. Another advantage is that these masks are fit tested to eliminate the possibility that droplets or particles do not leak around the mask.

This is important: Do not buy n95 mask for sale for your personal use, the CDC says. While those are the most effective -- filtering out 95% of all particles -- they are considered critical supplies and must continue to be reserved for health care workers and other medical first responders. In addition, N95 masks must be fitted to adhere to the unique contours of each doctor or nurse's face. You and your loved ones don't have access to that sort of expert fitting.

And be especially wary of the look-alike N95-type masks being sold at major retail distributors, Dr. Marybeth Sexton, an assistant professor of medicine in the division of infectious diseases at Emory University. "Some of those community-use N95 masks have exhalation valves in them," she said. "They do make them more comfortable to wear, but you're not protecting the people around you -- it's putting your airflow right out in the environment. "It may actually make things worse because it concentrates your breath into that valve, allowing it to come through with some force and the droplets may travel a little farther. So we strongly recommend that people don't wear a mask that has an exhalation valve.