Workplace exposure
BS EN 482:2021 pdf free.Workplace exposure一Procedures for the determination of the concentration of chemical agents一Basic performance requirements.
4 Classification
4.1 General
In this document, measurements are classified according to their purposes. These classifications are based upon the measurement strategy in EN 689.
4.2 Screening measurements of time-weighted average concentration
Screening measurements of time-weighted average concentration are performed to obtain semiquantitative information on exposure levels. Such information is used to identify potential health hazards, and to estimate the risk to health based on the likely severity of harm and the probability of its occurrence. These measurements can also determine if the exposure is significantly below or above the OELV. Apparatus intended for detection and concentration measurements of chemical agents, that meet the requirements of this document and is capable of reporting the time weighted average, can be used.
4.3 Screening measurements of variation of concentration In time and/or space
Screening measurements of variation of concentration in time and/or space are used to provide information on the likely pattern of the concentration of chemical agents in the air and to identify locations and periods of elevated exposure. The screening measurements also provide information on the location and intensity of emission sources and to estimate the effectiveness of ventilation or other technical measures. Apparatus intended for detection and concentration measurements of chemical agents, that meet the requirements of this document, can be used.
4.4 Measurements for comparison with OELVs
Provided the method meets established acceptable uncertainty criteria, measurements can be made for comparison with OELVs. Measurements can be taken to determine whether a worker’s exposure exceeds the OELV initially and repeated after any significant change in working conditions, industrial process, products or chemicals or OELV.
4.5 Periodic measurements
Periodic measurements are used to determine whether exposure conditions have changed since the measurements for comparison with OELVs were performed, or whether control measures remain effective. The interval between measurements should be established based on the initial occupational exposure assessment or subsequent amendments to it.
NOTE Since the composition of the workplace atmosphere will have been investigated during the initial occupational exposure assessment and the composition is known not to vary over time, it can be appropriate for periodic measurements to use procedures with lower selectivity.
5 Performance requirements
5.1 General
Performance requirements for measuring pi&.edures depend on the purpose for which they are used. The performance requirements for screening measurements are less stringent than for measurements for the comparison with limit values and periodic measurements. Therefore, the performance requirements for screening measurements in 5.2 and 5.3 are only given in general terms.
5.2 Screening measurements of time-weighted average concentration
The purpose of these measurements is described in 4.2. The measuring procedures shall include the following:
a) adequate selectivity for the chemical agent;
b) averaging time less than or equal to the limit value reference period;
c) measuring range that includes the limit value; and
d) expanded uncertainty that is fit for purpose.
5.3 Screening measurements of variation of concentration in time and/or space
The purpose of these measurements is described in 4.3. The measuring procedures shall include the following:
a) adequate selectivity for the chemical agent;
b) short averaging time (for variation of concentration in times 5 mm; for variation of concentration in space < 15 mm);
c) measuring range that is fit for purpose; and
d) expanded uncertainty that is fit for purpose.
5.4 Measurements for comparison with limit values and periodic measurements
5.4.1 General
A measuring procedure for a given limit value which meets the requirements given in 5.4.2 to 5.4.6 is called compliant method.
5.4.2 Unambigulty
A measuring procedure shall produce an unambiguous result for the concentration of the chemical agent being measured in the specified measuring range, i.e. an analytically determined value shall correspond to one concentration only within a known uncertainty.
5.4.3 Selectivity
The measuring procedure shall contain appropriate information about the nature and magnitude of any interference.
Requirements on selectivity vary from case to case, depending on what is known in advance about the workplace air. If the identity of all contaminants present is not known in advance then the measuring procedure shall have a high selectivity. If the identity of all contaminants is known prior to measurement and there are no interferents present, then a measuring procedure with a low selectivity can be used.
Where a particle size fraction, as defined in EN 481. is specified for an OELV, procedures for measuring chemical agents present as airborne particles shall prescribe a method for sampling the specified particle size fraction.
NOTE In addition to samplers meeting the requirements of EN 481, there are samplers which themselves define the sample (see EN 13205 series).
If different limit values are set for different species of a chemical agent, then the measuring procedure shall determine the individual species concerned.
5.4.4 Averaging time
The averaging time is equal to the sampling time, which shall be less than or equal to the limit value reference period. Depending on the sampling techniques, the sampling time can vary.
NOTE A full shift average concentration, typically the 8 h time-weighted concentration, gives a representative description of the occupational exposure situation.
Exposure peaks that can occur systematically or randomly during the shift should fulfil the short-term exposure limit conditions (see 5.4.6), if any.
5.4.5 Measuring range
The measuring range of the procedure listed in Table 1 shall cover at least the concentrations from 0,1 times to 2 times the limit value for long-term measurements, and from 0,5 times to 2 times the limit value for short-term measurements.
NOTE Reference [9] provides a list of International limit values for chemical agents (Occupational exposure limits, OELs).
5.4.6 Expanded uncertainty
The requirements for expanded uncertainty are given in Table 1.
5.4.7 Chemical agents where compliant methods are not available
Limit values are determined by authorities independently from those developing measuring procedures. If a measuring procedure is not available for a given limit value which meets the requirements given in 5,4.5 and 5.4.6 a measuring procedure should be used whose performance is closest to the requirements. The method employed should clearly state its limitations when measuring at the exposure limit.
5.5 Composite procedures
The performance requirements detailed in 5.2, 5.3 and 5.4 shall be fulfilled for the whole measuring procedure even if the measuring procedure consists of several distinct steps, for example, preparation of equipment, sampling, transport and storage, sample preparation and analysis. Each step of the measuring procedure may be tested individually and can be combined as a whole.
5.6 Transport, handling and/or storage
Transport, handling and/or storage of samples, if appropriate, shall be carried out in such a way that the physical and chemical integrity is maintained between sampling and analysis.
5.7 Environmental conditions
The effect of environmental conditions (for example, temperature, humidity, atmospheric pressure, and/or air speed) on the performance of the method shall be tested in the laboratory. Performance requirements concerning unambiguity, selectivity, expanded uncertainty, minimum measuring range and averaging time shall be fulfilled under the conditions likely to be encountered in the workplace.
NOTE Due to the time, cost, and effort involved, it is not practicable to carry out a comprehensive evaluation of environmental influences in the field and therefore laboratory tests are specified in this document. However, field tests can provide valuable information on the performance of measurement methods (for example, interferences from nearby workplaces).
The range of environmental conditions under which the performance requirements of 5.2 to 5.5 are fulfilled shall be specified in the measuring procedure.
5.8 Description of measuring procedure
The measuring procedure shall be documented in accordance with ISO 78-2. Any clause or subclause which is unnecessary in a particular case may be omitted, and others, if required, may be added in the most appropriate places. The description shall contain all necessary information to perform the measuring procedure, including information about the attainable expanded uncertainty, measuring range, averaging time, interferences and environmental or other conditions that can influence the performance of the measuring procedure.BS EN 482 pdf free download.Workplace exposure