3M's safety unit benefited from a "tremendous sequential surge" in demand for the masks last quarter because of the spread of H1N1, also known as swine flu, Chief Financial Officer Patrick Campbell said today on a conference call with analysts and investors. The investment will boost mask capacity worldwide by 10 percent.

"We are going to have some sustainable growth that comes from H1N1," Chief Executive Officer George Buckley said on the call. Demand for the protection is "huge," he said.

Masks to protect against the H1N1 influenza virus are on back-order through 2009, Buckley said. 3M and Kimberly-Clark Corp. are among the few manufacturers that make respiratory masks sophisticated enough to ward off swine flu, exacerbating shortages. Only masks rated N95 or above, which can filter at least 95 percent of airborne particles, are effective at blocking the virus, according to the U.S. Department of Health and Human Services.

Unless otherwise specified, "respirator" refers to an N95 or higher filtering face piece respirator certified by the CDC/National Institute for Occupational Safety and Health (NIOSH). A respirator is designed to protect the person wearing the respirator against breathing in very small particle aerosols that may contain viruses. A respirator that fits snugly on the face can filter out virus-containing small particle aerosols that can be generated by an infected person, but compared with a facemask it is harder to breathe through a respirator for long periods of time. Respirators are not recommended for children or people who have facial hair.