About

A high volume air sampler (HVAS) is an instrument used to measure airborne particulate matter in a large volume of ambient air by drawing it through a filter paper. It is a critical tool for monitoring air quality, as it collects particles like suspended particulate matter (SPM) or specific sizes like

PM10cap P cap M sub 10

10

or

PM2.5cap P cap M sub 2.5

2.5

, which can be used for mass concentration and chemical analysis. The device uses a powerful blower to pull a known volume of air through a filter over a specific time, and the change in the filter's weight determines the particle concentration.

• Air intake: A powerful blower pulls ambient air into the instrument at a high flow rate.
• Particle separation:
  • For SPM: The air is passed directly through a filter, which traps all suspended particles.
  • For
    

    PM10cap P cap M sub 10

    10
    or
    

    PM2.5cap P cap M sub 2.5

    2.5
    : A size-selective inlet is used, which removes larger particles by inertia, allowing only particles below a certain size (e.g.,
    

    10m10 mu m

    10
    ) to reach the filter.
• Filtration: The collected particles are retained on a high-efficiency filter paper, typically glass fiber.
• Concentration calculation: The filter paper is weighed before and after the sampling period, often after being conditioned to a standard temperature and humidity. The concentration is calculated by dividing the mass of the collected particles by the total volume of air sampled, typically using the formula:
  

  Concentration=(Final WeightInitial Weight)Volume of Air Sampledcap C o n c e n t r a t i o n equals the fraction with numerator open paren cap F i n a l space cap W e i g h t minus cap I n i t i a l space cap W e i g h t close paren and denominator cap V o l u m e space o f space cap A i r space cap S a m p l e d end-fraction

  =( )
  .

• Blower/Motor: A heavy-duty, continuous blower, often brushless, powers the high-volume airflow.
• Filter holder: A unit that holds the filter paper in place, often with a top-loading mechanism.
• Inlet: A specific component that can be a basic design for total suspended particulates (TSP) or a size-selective inlet for
  

  PM10cap P cap M sub 10

  10
  or
  

  PM2.5cap P cap M sub 2.5

  2.5
  .
• Flow control and measurement: Some samplers include mass flow controllers or a flow meter to ensure a consistent flow rate and can measure the total volume of air passed through the filter.
• Elapsed time indicator: A mechanical clock that tracks the hours the sampler has been running, useful for motor life tracking and sampling duration.

• Ambient air quality monitoring: To measure the concentration of pollutants in the air over a defined period.
• Source apportionment studies: To help identify the sources of air pollution.
• Chemical and biological analysis: The collected particles can be analyzed for their chemical constituents or biological components, like fungi and bacteria.
• Health risk assessment: To provide data for understanding the potential health impacts of inhaled particles.