Airborne Transmission

Question 1

How are respiratory pathogens thought to spread?

Answer 1

• direct physical contact between people
• indirect contact through contaminated objects (fomites)
• spray of droplets onto the mucous membranes
• inhalation of aerosols

Question 2

What respiratory infections are mostly transmitted by the airborne route?

Answer 2

• tuberculosis
• measles
• chickenpox

Question 3

Previously, what size of particulate is considered an aerosol?

Answer 3

<5um

Question 4

Previously, what size of particulate is considered a droplet?

Answer 4

> 5um-100um

Question 5

Previously, what size of particulate is considered a splatter?

Answer 5

> 100um

Question 6

Previously, what precautions must be taken for airborne spread?

Answer 6

• respiratory pathway
  
  • FFP3
  • masks
  • gowns
  • fallow times

Question 7

Previously, what precautions must be taken for droplet spread?

Answer 7

• non-respiratory pathway
  
  • FRSM
  • PPE

Question 8

Provide examples of droplet transmission

Answer 8

• coughs and sneezes
  
  • droplets of saliva and mucus

Question 9

What are aerosols?

Answer 9

particles that remain suspended due to size and/or environmental conditions

Question 10

What does 100um indicate for particulate size for droplet vs aerosol?

Answer 10

size threshold between droplets that fall to the ground faster than those that evaporate faster than they settle

Question 11

What are droplets?

Answer 11

particles that fall to the ground/surface undertake influence of gravity or t the momentum of an infected person’s exhaled air

Question 12

What are the 10 scientific reasons in support of airborne transmission of SARS-Cov2

Answer 12

1. super-spreading events
   
   • account for substantial transmission
2. long range transmission
   
   • between people in adjacent rooms
   • never in each others presence
3. asymptomatic or pre-symptomatic transmission
   
   • not yet coughing or sneezing
4. higher transmission indoors
   
   • substantially reduced by indoor ventilation
5. nosocomial infections
   
   • documented in healthcare with strict precautions
   • protection against droplets but not aerosols
6. viable infectious agent detected in the air
   
   • infectious in the air for up to 3 hours
   • half-life of 1.1 hours
7. identified in air filters and building ducts
   
   • in hospitals with infectious agents
   • areas only reached by aerosols
8. infected caged animals in separate cages
   
   • connected by air ducts
   • only adequately explained by aerosols
9. no study to provide strong evidence against airborne transmission
10. limited evidence to support alternative mode of transmission

Question 13

How many air changes per hour are recommended in a dental surgery ?

Answer 13

10 air changes per hour

Question 14

Why is ventilation important in the dental surgery?

Answer 14

• infection
  
  • closed settings
    
    • 1-3l/s/person
  • close contact
  • crowding
• occupational hazards
  
  • asthma
    
    • bacterial endotoxin
    • in dental unit waterlines
• important for human health
  
  • improved health
  • better concentration
  • environmental satisfaction
  • less work abscence
  • improved sleep quality
  • reduced air pollutants

Question 15

What does Regulation 6 of the Workplace Health, Safety and Welfare Regulations detail about building ventilation?

Answer 15

employers must ensure that every enclosed workplace is ventilated by a sufficient quantity of fresh or purified air?

Question 16

What is desirable building ventilation according to Scottish Guidance?

Answer 16

• 8-10l/s/person
• 800-1000ppm CO2

Question 17

How often should institutions provide a report on their ventilation situations?

Answer 17

every 2 months

Question 18

What are the 5 hierarchy of controls starting with most effective?

Answer 18

1. elimination
   
   • physically remove the hazard
2. substitution
   
   • replace the hazard
3. engineering controls
   
   • isolate people from the hazard
4. administrative controls
   
   • change the way people work
5. PPE
   
   • protect the worker with PPE

Question 19

What does the hierarchy of control aim to show?

Answer 19

design, elimination and engineering controls should be used and exhausted first as they are most effective when available

Question 20

Provide examples of engineering controls in dentistry

Answer 20

• rubber dam
• high volume aspiration
• effective surgery ventilation

Question 21

As well as PPE as the last line of defence on the hierarchy of control, what can considered similarly

Answer 21

vaccinations