Regulatory Guide – How to determine whether a UV source is a controlled apparatus (ARPANSA-GDE-1747)

 

1. Purpose

This document is provided to assist controlled persons to determine whether an ultraviolet (UV) source is classed as controlled apparatus under the Australian Radiation Protection and Nuclear Safety Act 1998 (the Act). In particular, it clarifies the conditions specified in section 9 of the Australian Radiation Protection and Nuclear Safety Regulations 2018 (the Regulations). A number of case studies where typical UV emitting apparatus have been assessed in accordance with this guide have been published in the document UV emitting apparatus – case studies.

This document is valid for both pulsed and continuous sources of UV radiation where the exposure duration is not less than 0.1 ms. It does not apply to UV lasers. Exposure to lasers are covered by laser standard AS/NZS IEC 60825.1 Safety of laser products.

Reference documents

Radiation Protection Standard for Occupational Exposure to Ultraviolet Radiation (2006), ARPANSA Radiation Protection Series No. 12 (RPS 12). Extracts from this document can be found in Appendix 1.

To fulfil the requirements of section 2.1 of RPS 12 supplementary information and management plans for controlling exposure to UVR can be found on the ARPANSA website:

• Management Plan
• Supplementary information

Read this document in conjunction with Regulatory Guide: UV emitting apparatus case studies.

2. Definitions

Exposure limit: the exposure which it is believed that nearly all workers can be repeatedly exposed to without adverse effect (exposure limits for UV are given in Schedule 1 of RPS 12).

Note: The exposure limits apply to artificial sources of UVR. Due to highly variable ambient solar UVR levels the application of exposure limits is not practical and limiting solar UVR exposure to as low as possible is the most effective approach.

Permissible exposure time, t_PET: the time it takes to reach the exposure limit (calculated according to Schedule 1 of RPS 12).

3. Controlled apparatus

In section 4 Group 1 table of the Regulations defines an optical source, other than a laser product, emitting ultraviolet radiation, infrared or visible light as controlled apparatus.

4. Criteria to be satisfied

Section 9 of the Regulations consists of two separate criteria, both of which must be fulfilled for the apparatus to be classed as controlled apparatus.

The first criterion, paragraph 9(1)(b) concerns source emission. It is fulfilled if the apparatus produces non-ionising radiation that could lead to a person being exposed to radiation levels exceeding the non-ionizing radiation exposure limits. For UVR the relevant standard referred to in section 4 is Radiation Protection Standard for Occupational Exposure to Ultraviolet Radiation (2006), ARPANSA Radiation Protection Series No. 12 (RPS 12).

The second criterion, paragraph 9(1)(c) is based on the accessibility of the source. Factors determining whether radiation above the exposure limits is accessible to persons have to be evaluated. The condition is fulfilled if excess levels of radiation are readily accessible to persons in any of the following situations:

• in the course of intended operations or procedures of the apparatus; or
• as a result of a reasonably foreseeable abnormal event involving the apparatus; or
• as a result of a reasonably foreseeable single element failure of the apparatus; or
• without the use of tools or other specialised equipment required to remove protective barriers or access panels.

If the apparatus is not one of the exempt dealings in section 44(7) of the Regulations the procedure in the next section describes how to go through these two criteria to determine whether a UVR source is classed as controlled apparatus or not.

5. Procedure

This procedure (as show by the flow chart on page 4) will assist you to determine whether your apparatus is controlled or not. 

1. If the apparatus is a transilluminator or germicidal lamp where the emission is accessible, it is classed as controlled apparatus.
2. If the apparatus is a fluorescence microscope, a spectrophotometer or a high-performance liquid chromatography (HPLC) where the light source is completely enclosed, it is not controlled apparatus.
3. If there is a reasonably foreseeable abnormal event involving the apparatus that would lead to a person being exposed to levels above the exposure limits, the apparatus is classed as controlled apparatus. Examples of this are: forgetting or using the wrong PPE, possible exposure during normal maintenance, not using prescribed shielding to cover a sample, easy overriding of an interlock etc.
4. If there is a reasonably foreseeable single element failure of the apparatus that would lead to a person being exposed to levels above the exposure limits, the apparatus is classed as controlled apparatus. An example of this is a malfunctioning interlock. A failsafe interlock would not lead to a person being exposed as no UVR is emitted if the interlock fails.
5. If a person can receive excess levels of radiation when removing protective barriers or access panels that do not require the use of tools or other specialised equipment, then the apparatus is classed as controlled apparatus.
6. Determine if the source emits UV radiation that could lead to a person being exposed to radiation levels in excess of the exposure limits in the course of intended operations or procedures. Calculate the permissible exposure time, t_PET, according to the method described in Schedule 1 of RPS 12.

Notes:

The distance to the source when the unit is in operation should be taken into account. Using the inverse square law the radiation level is calculated at the position where the closest person is situated. If the unit is handheld and no distances are specified: assume that the skin and eyes are 20 cm and 50 cm, respectively, from the source.

Embedded devices can be designed in such a way that it can be considered safe for their intended use and during normal operation as the emission hazard only becomes accessible during service or maintenance. i.e. protective housing, interlocks and other organisational safety measures. The servicing of embedded UV sources can increase the risk of injury as the servicing may include various adjustments. To carry out servicing in a safe manner it may be necessary to implement temporary procedures and safeguards appropriate to the increased level of risk. Manufacturers may provide advice on safe procedures during servicing and maintenance.

Compare with the maximum exposure duration, t_exp.

If  t_exp> t _PET  the apparatus is classed as controlled apparatus.

If      the apparatus is not classed as controlled apparatus.

Flowchart for determining whether a UV source is a controlled apparatus

 

Appendix 1

Extracts from Schedule 1 Radiation Protection Standard for Occupational Exposure to Ultraviolet Radiation (2006)

Radiation Protection Series No. 12

Exposure Limits (EL) for UVR from Artificial Sources ¹

S1.1	The EL for occupational exposure to UVR incident upon the skin or eye where irradiance values are known and the exposure duration is controlled are as below. Note that S1.2 and S1.3 must both be satisfied independently.
S1.2	For the UV-A spectral region 315 to 400 nm, the total radiant exposure on the unprotected eye must not exceed 10 kJ.m–2 within an 8 hour period and the total 8 hour radiant exposure incident on the unprotected skin must not exceed the values given in Table 1. Values for the relative spectral effectiveness are given up to 400 nm to expand the action spectrum into the UV-A for determining the EL for skin exposure.
S1.3	In addition, the ultraviolet radiant exposure in the actinic UV spectral region (UV-B and UV-C from 180 to 315 nm) incident upon the unprotected skin and unprotected eye(s) within an 8 hour period must not exceed the values given in Table 1.
S1.4	For broadband sources emitting a range of wavelengths in the ultraviolet region (ie most UVR sources), determination of the effective irradiance of such a broadband source is done by weighting all wavelengths present in the emission with their corresponding spectral effectiveness by using the following weighting formula: Eeff       =       ∑Eλ. Sλ. ∆λ where Eeff       =       Effective irradiance in W.m–2 (J.s–1.m–2) normalised to a monochromatic source at 270 nm Eλ              =       Spectral irradiance in W.m–2.nm Sλ              =       Relative spectral effectiveness (unitless) ∆λ             =       Bandwidth in nanometres of the calculated or measurement intervals
S1.5	Permissible exposure time in seconds for exposure to actinic UVR incident upon the unprotected skin or eye may be computed by dividing 30 J.m–2 by Eeff in W.m–2. The maximum exposure duration may also be determined using Table 2 of this Schedule which provides representative exposure durations corresponding to effective irradiances in W.m–2 (and μW.cm-2).

¹ These exposure limits are intended to be used as guidelines only for Solar UVR exposure.

 

Table 1: Ultraviolet radiation exposure limits and Relative Spectral Effectiveness

Wavelengtha (nm)	Exposure limit (J.m-2)	Exposure limit (mJ.cm-2)	Relative Spectral Effectiveness Sλ
180	2 500	250	0.012
190	1 600	160	0.019
200	1 000	100	0.030
205	590	59	0.051
210	400	40	0.075
215	320	32	0.095
220	250	25	0.120
225	200	20	0.150
230	160	16	0.190
235	130	13	0.240
240	100	10	0.300
245	83	8.3	0.360
250	70	7.0	0.430
254b	60	6.0	0.500
255	58	5.8	0.520
260	46	4.6	0.650
265	37	3.7	0.810
270	30	3.0	1.000
275	31	3.1	0.960
280b	34	3.4	0.880
285	39	3.9	0.770
290	47	4.7	0.640
295	56	5.6	0.540
297b	65	6.5	0.460
300	100	10	0.300
303b	250	25	0.120
305	500	50	0.060
308	1 200	120	0.026
310	2 000	200	0.015
313b	5 000	500	0.006
315	1.0 × 104	1.0 × 103	0.003
316	1.3 × 104	1.3 × 103	0.0024
317	1.5 × 104	1.5 × 103	0.0020
318	1.9 × 104	1.9 × 103	0.0016
319	2.5 × 104	2.5 × 103	0.0012
320	2.9 × 104	2.9 × 103	0.0010
322	4.5 × 104	4.5 × 103	0.00067
323	5.6 × 104	5.6 × 103	0.00054
325	6.0 × 104	6.0 × 103	0.00050
328	6.8 × 104	6.8 × 103	0.00044
330	7.3 × 104	7.3 × 103	0.00041
333	8.1 × 104	8.1 × 103	0.00037
335	8.8 × 104	8.8 × 103	0.00034
340	1.1 × 105	1.1 × 104	0.00028
345	1.3 × 105	1.3 × 104	0.00024
350	1.5 × 105	1.5 × 104	0.00020
355	1.9 × 105	1.9 × 104	0.00016
360	2.3 × 105	2.3 × 104	0.00013
365b	2.7 × 105	2.7 × 104	0.00011
370	3.2 × 105	3.2 × 104	0.000093
375	3.9 × 105	3.9 × 104	0.000077
380	4.7 × 105	4.7 × 104	0.000064
385	5.7 × 105	5.7 × 104	0.000053
390	6.8 × 105	6.8 × 104	0.000044
395	8.3 × 105	8.3 × 104	0.000036
400	1.0 × 106	1.0 × 105	0.000030

^a Wavelengths chosen are representative; other values should be interpolated at intermediate wavelengths

^b Emission lines of a mercury discharge spectrum

Table 2: Limiting UV exposure durations based on EL 

Duration of exposure per day		Effective irradiance Eeff(W.m–2)  |  Eeff (µW.cm–2)
8	hr	0.001	0.1
4	hr	0.002	0.2
2	hr	0.004	0.4
1	hr	0.008	0.8
30	min	0.017	1.7
15	min	0.033	3.3
10	min	0.05	5
5	min	0.1	10
1	min	0.5	50
30	sec	1.0	100
10	sec	3.0	300
1	sec	30	3 000
0.5	sec	60	6 000
0.1	sec	300	30 000