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Current Affairs

Measuring aerosols with particle counter

Date: 29 December 2020 Tags: Miscellaneous

Issue

Scientists have demonstrated a simpler alternative use a commercially available particle counter to analyse risks associated with coronavirus infection.

 

Background

The concentration of aerosols in public spaces can give a measure of infection risk, but making that measurement usually requires specialists and specialised equipment.

 

Details

  • The novel coronavirus spreads primarily via aerosols, or tiny droplets generated by a cough or a sneeze that may be carrying the virus.

  • The reading we get from such particle counters, however, will include background dust besides the aerosols. 

  • There is a need to distinguish these dust particles from aerosols that arise from people breathing, speaking, sneezing, and coughing.

  • The amount of aerosol can be arrived by measuring the amount of dust particles when there are no aerosols and then take the difference with when people do generate aerosols by speaking or coughing.

  • For validation, the researchers compared their measurements with those from specialised laboratory techniques.

  • Aerosol concentration is often measured using a technique called laser diffraction, in which a laser beam passing through a sample lights up different-sized particles differently.

  • Results from the highly specialised technique and the method used in the study, the researchers found, matched up perfectly. 

  • The findings suggest that well-ventilated areas can have aerosol concentrations more than 100 times lower than poorly ventilated areas, such as public elevators or restrooms.

Aerosols

An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog, mist, dust, forest exudates and geyser steam.