Novel H1N1 Swine flu the role of face masks

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Novel H1N1 Swine flu the role of face masks

• The new H1N1 Swine flu virus, as
  photographed by the Centers for Disease Control
  (CDC)

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The new H1N1 (Swine flu) strain

• This strain represents a genetic re-assortment of
  swine, human, and avian strains of influenza. It
  is not clear yet how this virus arose or was
  initially transmitted to humans. (CDC April 23
  2009)

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Transmission

• There are two primary routes by which influenza
  virus exits the respiratory tract of an infected
  person
• (i) expulsion of the virus into the air through
  sneezing, coughing, speaking, breathing or
  through aerosol-generating medical procedures,
• (ii) by direct transfer of respiratory secretions
  to another person or surface. The new host
  acquires the virus either by inhalation of the
  infectious particles from the air or by contact
  with infectious material directly or via
  self-innoculation through a contaminated
  hand.(Council of Canadian Academies, Jan 2008)

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Transmission

• Person emits respiratory particles in a wide
  range of sizes.
• Expelled particles can be categorized into two
  groups depending on how they travel ballistic
  particles and inhalable particles.
• Ballistic particles diameter gt/100 µm and
  are predominantly affected by gravity.
• Inhalable particles diameters of 0.1 to 100
  µm
• and, depending on size and shape, they may remain
  in the air from seconds to days.

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What is an N95 Respirator/Mask?

• NIOSH certified N95 respirators/masks are
  designed to help provide respiratory protection
  for the wearer. The N95 respirator/mask has a
  filter efficiency level of 95 or greater against
  particulate aerosols free of oil when tested
  against a 0.3 micron particle. It is fluid
  resistant, disposable and may be worn in surgery.
  
• The "N" means "Not resistant to oil". (This means
  that any oil-based residue that comes into
  contact with the mask reduces its effectiveness.)
  The "95" refers to a 95 filter efficiency.

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Use of Facemasks and Respirators

• Information on the effectiveness of facemasks and
  respirators for the control of influenza in
  community settings is extremely limited. Thus, it
  is difficult to assess their potential
  effectiveness in controlling swine influenza A
  (H1N1) virus transmission in these settings. (
  CDC April 27 2009 - Face masks refer to surgical
  like masks and Respirators refer to masks such as
  the N95 and other higher filtration masks)

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Use of Facemasks and Respirators

• The use of facemasks or respirators is only one
  part of a combination of approaches that can be
  used to help reduce the spread of virus from
  infectious to non-infected persons..(CDC)

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Use of Facemasks and Respirators

• Facemasks (e.g. surgical masks) do not form a
  tight seal on the wearers face and are not
  designed to filter out small particles that can
  be inhaled and that may have a role in influenza
  transmission. However, facemasks are useful in
  blocking large infectious droplets (created when
  a person coughs or sneezes nearby) from landing
  on the susceptible mucous membranes of the
  wearers nose and mouth - this is thought to be
  an important mode of influenza transmission.

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Use of Facemasks and Respirators

• Facemasks have the advantages of being relatively
  comfortable to wear and inexpensive to purchase.
  In addition, small facemasks are available that
  can be worn by children, but it may be
  problematic for children to wear them correctly
  and consistently. Moreover, no facemasks (or
  respirators) have been cleared by the FDA
  specifically for use by children.

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Use of Facemasks and Respirators

• NIOSH-certified N95 and higher filtering
  face-pieces are made of dense material that is
  certified to filter out very small particles that
  can be inhaled. They also will block both small
  splashes and large droplets.
• To be most effective, these types of respirators
  should form a tight seal against the wearers
  face and be fit-tested by a person trained to
  do this.
• Fit-testing involves selecting the correct size
  and type of respirator. The wearer is exposed to
  non-toxic powder which can be tasted if it
  penetrates the respirator.

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Use of Facemasks and Respirators

• N95 respirators are most effective and safest
  when the wearer has been properly fitted (i.e.
  fit-tested) and provided with a health assessment
  and training to use the device.
• Respirators are not designed to form a tight fit
  on people with very small faces (e.g. children)
  or who adults with have facial hair (e.g.
  beard/moustache). (CDC)

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Use of Facemasks and Respirators

• Both facemasks and respirators may be beneficial
  in discouraging wearers from inadvertently
  touching their nose or mouth with unwashed hands,
  which could help prevent virus transmission and
  infection.

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Consideration for use of facemasks and Respirators

• Respirators, if worn and fitted correctly, will
  provide protection against most small particles,
  although they are not specifically designed to
  prevent transmission of infectious agents.
• There is limited evidence available to suggest
  that use of a respirator without fit-testing may
  still provide better protection than a facemask
  against inhalation of small particles.

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Use of Facemasks and Respirators

• According to the CDC, if used correctly,
  facemasks and respirators may help reduce the
  risk of getting influenza, but they should be
  used along with other preventive measures, such
  as avoiding close contact with others and
  maintaining good hand hygiene.
• A respirator that fits snugly on your face can
  filter out small particles that can be inhaled
  around the edges of a facemask, but compared with
  a facemask it is harder to breathe through a
  respirator for long periods of time.

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Health Canadas take on appropriate Respirators

• Health Canada recognizes that many institutions
  and other health settings may not use N95 masks
  that are NIOSH approved, and considers masks
  fulfilling the following requirements as the
  "equivalent" to NIOSH certified N95 masks
•       Filter particles one micron in size or
  smaller
•       Have a 95 filter efficiency
•       Provide a tight facial seal (less than 10
  leak).

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Considerations for use of Facemasks and
Respirators

• To offer optimal protection, both facemasks and
  respirators need to be worn correctly and
  consistently throughout the time they are used.
• Facemasks can be worn comfortably for longer
  periods than respirators, but they are not
  designed to prevent inhalation of small
  particles.

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Considerations for use of Facemasks and
Respirators

• Respirators, if worn and fitted correctly, will
  provide protection against most small particles,
  in the size range that can be inhaled into the
  respiratory tract, including the entire range of
  nasopharyngeal, tracheobronchial and
  alveolar-sized particles.
• They can be re-used by the same wearer if they
  are stored in a plastic bag.

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Conclusions on Protective Measures against
Influenza Transmission

• 1. When exposure to an infected person is
  required or unavoidable, respirators provide the
  final layer of protection i.e. they should be
  used in combination with other measures.
• 2. N95 respirators protect against the inhalation
  of
• nasopharyngeal, tracheobronchial and
  alveolarsized particles.
• 3. Surgical masks worn by an infected person may
  play a role in the prevention of influenza
  transmission by reducing the amount of infectious
  material that is expelled into the environment.

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Conclusions on Protective Measures against
Influenza Transmission

• 4. Both surgical masks and N95 respirators offer
  a
• physical barrier to contact with contaminated
  hands and ballistic trajectory particles.
• 5. The efficiency of the filters of surgical
  masks to block penetration of these airborne
  particles is highly variable. When combined with
  the inability to ensure a sealed fit, these
  factors suggest that surgical masks offer no
  significant protection against the inhalation of
  alveolar and tracheobronchial-sized particles.

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Conclusions on Protective Measures against
Influenza Transmission

• 6. The efficiency of the filters of surgical
  masks to block penetration of nasopharyngeal-sized
  particles is unknown. The lack of a sealed fit
  on a surgical mask will allow for the inhalation
  of an unknown quantity of nasopharyngeal-sized
  particles.
• (Council Of Canadian Academies- January 2008 )