IB4 - The Monitoring and Measuring of Hazardous Substances Flashcards
What does OEL mean?
The definition of OEL is the maximum concentration of an airborne substance, averaged over a reference period, to which employees may be exposed by inhalation.
It is usually expressed in units of mg/m3 or ppm. Two different reference time periods are used and the OELs are expressed in terms of these time periods - either Long Term Exposure Limits (LTEL) measured over an eight hour period, or Short Term Exposure Limits (STEL) measured over 15-minute periods.
If STEL is unknown, what may be used?
If the short term (15 minutes) limit is unknown then 3 x LTEL may be used.
Identify the periods of time for which records should be kept, and the factors that determine the period of time.
The length of time for which records have to be kept depends on the type of measurement taken. For individuals (personal dosimetry) the period is for at least 40 years, in any other cases (e.g. static sampling) for at least five years.
Which equipment can be used to determine the amount of inhalable and respirable dust?
For inhalable dust an IOM sampler can be used.
For respirable dust a Cyclone sampler can be used.
Mention a method for gravimetric analysis
The MDHS 14/4 Method for the Determination of Hazardous Substances.
Explain the inhalable, thoracic and respirable size fractions
(a) Inhalable fraction – this approximates to the fraction of airborne material that enters the nose and mouth during breathing, and is therefore available for deposition anywhere in the respiratory tract.
(b) Thoracic fraction – this is the fraction of inhaled airborne material penetrating beyond the larynx.
(c) Respirable fraction – this is the inhaled airborne material that penetrates to the lower gas exchange region of the lung.
Controls which are commonly forgotten to mention are:
Test, Calibration and Maintenance of equipment.
Health surveillance with specific requirements e.g. spirometry or lung function testing.
What is Occupational hygiene?
Is the anticipation, recognition, evaluation, control, and confirmation of protection from hazards at work that may result in injury, illness, or affect the well being of workers
Define a Standard Threshold Shift
A reviewer of audiograms will identify an STS (or “Standard Threshold Shift”) if the hearing threshold has changed (relative to the baseline audiogram) an average of 10dB or more at 2000, 3000, or 4000 Hz in either ear.
Mention benefits and limitations of audiometry
The benefits of audiometry include:
- Evidence of effectiveness of hearing conservation programme
- Pre-employment identification of pre-existing problems
- Identification of early signs of noise induced hearing loss
- Basis to defend claims of noise induced hearing loss
Limitations of audiometry include:
- Not preventative
- Information may precipitate claims
- Possible inaccuracies in data
- Doesn’t identify source of noise induced hearing loss.
Identify FOUR environmental parameters that affect thermal comfort
air temperature, radiant temperature, relative humidity, air velocity
Identify THREE other parameters that affect thermal comfort
Metabolic rate, clothing, sweat rate, duration of exposure.
In addition, activity or work rate are also relevant.
Outline the purpose of WBGT
The purpose of a heat stress index such as WBGT is that it provides a single number representation of the severity of a thermal environment, which can then be compared to standards and can be helpful when risk assessing a thermal environment
