page_title: 2009 swine flu pandemic
section_title: Face masks
hierarchical_section_title: 2009 swine flu pandemic / Prevention / Infection control / Face masks
caption_attribution_description: English: Influenza-Shock at Osaka（may,2009） 日本語: 新型インフルエンザ（ブタインフルエンザとも）の影響でマスクをする市民ら（2009年5月MASA (talk)がJR大阪環状線車内で撮影）
context_page_description: The 2009 swine flu pandemic was an influenza pandemic that lasted for about 19 months, from January 2009 to August 2010, and was the second of two pandemics involving H1N1 influenza virus. First described in April 2009, the virus appeared to be a new strain of H1N1, which resulted from a previous triple reassortment of bird, swine, and human flu viruses further combined with a Eurasian pig flu virus, leading to the term "swine flu".
  Some studies estimated that the actual number of cases including asymptomatic and mild cases could be 700 million to 1.4 billion people—or 11 to 21 percent of the global population of 6.8 billion at the time. The lower value of 700 million is more than the 500 million people estimated to have been infected by the Spanish flu pandemic.
  The number of lab-confirmed deaths reported to the WHO is 18,449, though this 2009 H1N1 flu pandemic is estimated to have actually caused about 284,000 deaths. A follow-up study done in September 2010 showed that the risk of serious illness resulting from the 2009 H1N1 flu was no higher than that of the yearly seasonal flu. For comparison, the WHO estimates that 250,000 to 500,000 people die of seasonal flu annually.
context_section_description: The U.S. CDC did not recommend the use of face masks or respirators in non-health care settings, such as schools, workplaces, or public places, with a few exceptions: people who were ill with the virus when around other people, and people who were at risk for severe illness while caring for someone with the flu. There was some disagreement about the value of wearing face masks, as some experts feared that masks may have given people a false sense of security and should not have replaced other standard precautions.
  Yukihiro Nishiyama, professor of virology at Nagoya University's School of Medicine, commented that the masks are "better than nothing, but it's hard to completely block out an airborne virus since it can easily slip through the gaps".
  According to mask manufacturer 3M, masks will filter out particles in industrial settings, but "there are no established exposure limits for biological agents such as swine flu virus". However, despite the lack of evidence of effectiveness, the use of such masks is common in Asia. They are particularly popular in Japan, where cleanliness and hygiene are highly valued and where etiquette obligates those who are sick to wear masks to avoid spreading disease.
caption: Osaka Loop Line, Japan
exif: {"Image Make": "CASIO COMPUTER CO.,LTD.", "Image Model": "EX-Z700", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "1.01", "Image DateTime": "2009:05:18 22:59:14", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "282", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 51, 48, 48, 0, 0, 0, 5, 0, 1, 0, 22, 0, 22, 0, 2, 1, 0, 0, 0, 1, 0, 5, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 16, 128, 0, 0, 0]", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "33746", "Thumbnail JPEGInterchangeFormatLength": "8764", "EXIF ExposureTime": "1/30", "EXIF FNumber": "33/10", "EXIF ExposureProgram": "Program Normal", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2009:05:18 22:59:14", "EXIF DateTimeDigitized": "2009:05:18 22:59:14", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "208/125", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "14/5", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "9", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1600", "EXIF ExifImageLength": "1200", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "33622", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0/0", "EXIF FocalLengthIn35mmFilm": "55", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "High gain up", "EXIF Contrast": "Hard", "EXIF Saturation": "Hard", "EXIF Sharpness": "Hard"}