Regulations > Regulations for Hazardous Chemical Agents, 2020 > Annexures > Annexure 3 : Hazardous Chemical Agent Guidelines > Guidance on medical surveillance and biological monitoring > Applying occupational exposure limits > Particle size selective criteria for sampling of total airborne particulate and respirable particulate

68.

Unless specified otherwise, OELs for all airborne particulates (HCAs comprising of airborne particulates) refer to the inhalable particulate matter of that agent. Sampling of these airborne particulates must be carried out with a method specifically designed to collect the inhalable particulate matter of the HCA. Inhalable particulate matter approximates to the particle size fraction of particulates that can be suspended in air with an upper size limit of approximately 100 micrometres (μm) in aerodynamic diameter.

69.

Respirable particulate matter refers to materials that are hazardous when deposited in the gas exchange region of the lung. Respirable particulates generally have an aerodynamic diameter of less than 10 μm and a median of 4 μm. These materials are sampled with a respirable particulate matter sampler with a median cut point of 4 μm.

Inhalable fraction: the mass fraction of total airborne particles which is inhaled through the nose and mouth, measured by a size-selective device conforming to a sampling efficiency curve which passes through the points in the table below.

Aerodynamic diameter (μm)	Inhalable fraction (%)
0	100
1	97
2	94
5	87
10	77
20	65
30	58
40	54,5
50	52,5
100	50

Thoracic fraction: the mass fraction of inhaled particles which penetrate beyond the larynx, measured by a size-selective device conforming to a sampling efficiency curve which passes through the points in the table below.

Aerodynamic diameter (μm)	Inhalable fraction (%)
0	100
2	97
4	89
6	80,5
8	67
10	50
12	35
14	23
16	15
18	9,5

Respirable fraction: the mass fraction of inhaled particles which penetrate to the unciliated airways, measured by a size-selective device conforming to a sampling efficiency curve which passes through the points in the table below.

Aerodynamic diameter (μm)	Inhalable fraction (%)
0	100
1	97
2	91
3	74
4	50
5	30
6	17
7	9
8	5
10	1

Occupational Health and Safety Act, 1993 (Act No. 85 of 1993)

Regulations

Regulations for Hazardous Chemical Agents, 2020

Annexures

Annexure 3 : Hazardous Chemical Agent Guidelines

Guidance on medical surveillance and biological monitoring

Applying occupational exposure limits

Particle size selective criteria for sampling of total airborne particulate and respirable particulate