W201 Day 2–Overnight Questions

Measurement of airborne contaminants

  1. For each of the terms below indicate what is the state of matter (Gas, Liquid or Solid) and define the term.

Term / State of matter / Definition
Vapour
Mist
Fume
Dust
Aerosol
Fibre
  1. In each of the following pairs indicate which generally involves the larger particles.
  1. Fume or dust
  1. Vehicle exhaust or cement dust
  1. Respirable particles or inhalable particles
  1. Mist or spray
  1. Viruses or bacteria
  1. For each of the following, name the equipment and indicate what substances and what type of sampling it might be used for.

  1. The data below represents the information collected during an air monitoring exercise for Total inhalable dust. For each sample calculate the measured concentration of dust in mg.m-3.

Sample No: / Start (hh:mm) / Stop (hh:mm) / Flow Rate(l.min-1) / Filter Pre weight (mg) / Filter post weight (mg)
1 / 09:00 / 17:00 / 2.0 / 25.34 / 25.59
2 / 09:15 / 12:30 / 2.0 / 24.99 / 27.49
3 / 13:30 / 16:58 / 2.0 / 26.01 / 28.09
4 / 08:00 / 16:30 / 2.0 / 25.45 / 26.21
5 / 09:17 / 15:16 / 2.0 / 25.11 / 26.37
Sampling Time (mins) / Weight Change of Filter (mg) / Volume of air sampled
(litres) / Concentration (mg.m-3)

Hygiene standards and occupational exposure limits

  1. For each of the following measured exposures calculate the appropriate 8-hour time weighted average
  1. The operator works for eight hours on a process in which he is exposed to a substance hazardous to health. The average exposure during that period is measured as 0.15 mg.m-3.
  1. Working periods may be split into several sessions for the purpose of sampling to take account of rest and meal breaks etc. This is illustrated by the following example:

Working period / Exposure (mg.m-3) / Duration of sampling (h)
0800-1030 / 0.32 / 2.5
1045-1245 / 0.07 / 2
1315-1415 / 0.2 / 1
1430-1600 / 0.1 / 1.5

Exposure is assumed to be zero during the periods 1030 to 1045, 1245 to 1315 and 1415 to 1430.

  1. An operator works for eight hours during the night shift on a process in which he is intermittently exposed to a substance hazardous to health. The operator’s work exposure is outlined in the below table. Calculate the 8 hour TWA.

Working period / Task / Exposure (mg.m-3)
2200 to 2400 / Helping in workshop / 0.1 (known to be exposure of full-time group in workshop)
2400 to 0100 / Cleaning elsewhere in factory / 0 (assumed)
0100 to 0400 / Working in canteen / 0 (assumed)
0400 to 0600 / Cleaning-up after breakdown in workshop / 0.21 measured

Biological monitoring and Health Surveillance

  1. What are the three main reasons for undertaking Health Surveillance?
  1. What kind of information can biological monitoring provide?

CONTROL

  1. Name the elements of the Hierachy of Control and list them in order of performance.

VENTILATION

  1. Name the general components of a Local Exhaust Ventilation system
  1. What elements need to be considered when trying to control an airborne contaminant using Local Exhaust Ventilation?
  1. Give names to each of the hoods shown and describe how they control airborne contaminants.

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