Daily Archives: August 19th, 2009

Know Your Masks, If You Must Mask

As the paranoia spreads with the increasing number of reported deaths worldwide, I couldn’t help noticing the plethora of mask types that are being worn. Is the right mask being worn? More important, are  people  wearing them for the correct reasons?

First a few facts:

  1. The H1N1 virus, like any flu virus, spreads in the air as droplets, mainly through the coughs and sneezes of people who are sick with the virus, but it may also be spread by touching infected objects (including hands) and then touching your nose or mouth.
  2. The flu virus is 0.08-0.12 microns in size (micron= one millionth of a metre). Small enough to pass through most masks!

Facemasks galore..but only the N95 is truly effective, as worn by the male uniformed personnel above (courtesy of Sunday Mirror)


The N95 Mask..so-called because 95% of airborne particles are filtered off

So, using an ordinary facemask, whether single-ply, 2 ply or 3 ply, is really to protect other people from you. Its designed to keep the germs in and should be worn by those having a influenza-like illness(ILI).(fever 37.8°C or greater) and a cough and/or a sore throat).

Otherwise, if you want to keep the germs out & protect yourself from getting the flu, then you need to use the N95 mask (also called respirator). It must be tight-fitting and is rather uncomfortable to wear over long periods as extra effort is sometimes needed to inhale.

Whichever mask you use, you need to practise social distancing (2 metres away), social etiquette (blocking off a sneeze and cough) and frequent handwashing.

Should the general public wear facemasks?

There is no evidence to suggest that this is a useful preventative measure. Unless of course, you have a flu-like illness (to prevent others from catching it) or you are in close contact with a probable, suspected or confirmed person. Confused with all these terms? The US Centre for Disease Control has made it somewhat easier by defining it:

A confirmed case of A (H1N1) virus infection is defined as a person with an influenza-like illness with laboratory confirmed novel influenza A (H1N1) virus infection by one or more of the following tests:

  1. real-time RT-PCR
  2. viral culture

A probable case of A (H1N1) virus infection is defined as a person with an influenza-like-illness who is

  • positive for influenza A, but negative for human H1 and H3 by influenza RT_PCR

A suspected case of  A (H1N1) virus infection is defined as a person who does not meet the confirmed or probable case definition, and is not novel H1N1 test negative, and is/has:

  • a previously healthy person < 65 years hospitalized for ILI


  • ILI and resides in a state without confirmed cases, but has traveled to a state or country where there are one or more confirmed or probable cases


  • ILI and has an epidemiologic link in the past 7 days to a confirmed case or probable case.

If you would like to know more about facemasks and who exactly should be wearing one, this CDC website is recommended.

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