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LEGAL ACTS OF THE REPUBLIC OF LATVIA
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Republic of Latvia

Cabinet
Regulation No. 731
Adopted 30 June 2009

Labour Protection Requirements for the Protection of Workers from the Risk Arising from Artificial Optical Radiation in the Work Environment

Issued pursuant to
Section 25, Paragraph eighteen
of the Labour Protection Law

I. General Provisions

1.These Regulations prescribe the labour protection requirements for the protection of workers from the risk arising or likely to arise from exposure to artificial optical radiation (hereinafter - optical radiation) to workers during working hours, especially to the eyes and to the skin.

2. Optical radiation is any electromagnetic radiation in the wavelength range between 100 nm and 1mm. The following types of optical radiation exist:

2.1. non-coherent radiation - any optical radiation other than laser radiation:

2.1.1. ultraviolet radiation - optical radiation of wavelength range between 100 nm and 400 nm. The ultraviolet range is divided into UVA (315-400 nm), UVB (280-315 nm) and UVC (100-280 nm);

2.1.2. visible radiation - optical radiation of wavelength range between 380 nm and 780 nm; and

2.1.3. infrared radiation - optical radiation of wavelength range between 780 nm and 1 mm. The infrared range is divided into IRA (780-1400 nm), IRB (1400-3000 nm) and IRC (3000 nm-1 mm);

2.2. laser radiation - optical radiation from a laser device, with which electromagnetic radiation may be produced or amplified in the optical radiation wavelength range, primarily by the process of controlled stimulated emission.

3. Irradiance or power density is the radiant power incident per unit area upon a surface, expressed in watts per square metre (W/m2).

4. Radiant exposure is the time integral of the irradiance, expressed in joules per square metre (J/m2).

5. Radiance is the radiant flux or power output per unit solid angle per unit area, expressed in watts per square metre per steradian (W/m2 x sr).

6. The level of exposure to optical radiation is the combination of irradiance, radiant exposure and radiance to which a worker is exposed.

7. These Regulations shall apply to all areas of employment, in which workers are or may be exposed to optical radiation in the work environment.

8. An employer shall not expose workers to such optical radiation exposure which exceeds the exposure limit values for non-coherent radiation (Annex 1) and the exposure limit values for laser radiation (Annex 2).

9. The exposure limit values are restrictions to optical radiation exposure, upon compliance with which workers exposed to radiation are protected from harmful effects thereof on health.

10. An employer shall be responsible for the compliance with these Regulations.

11. The State Labour Inspectorate shall control the compliance with the labour protection requirements.

II. Determination of Exposure to Optical Radiation and Assessment of the Risk Caused

12. An employer shall, at all workplaces, perform the initial assessment of the risk arising from optical radiation, specifying whether it includes sources of optical radiation, which might cause harm to the health of workers.

13. If a source of optical radiation is present in the workplace or the results of a health examination of workers confirm that health disorders of workers have been caused by or may have been caused by exposure to optical radiation, the employer shall evaluate the risk caused by optical radiation in accordance with the regulatory enactments regarding the procedures for the performance of internal supervision of the work environment.

14. If an employer establishes that optical radiation causes or may cause risk to the safety and health of workers, he or she shall, if necessary, perform measurements or calculations of optical radiation in accordance with the results acquired, taking into account the exposure limit values (Annex 1 and 2), as well as the information provided by the manufacturer of work equipment regarding the irradiance levels (if the relevant equipment creates optical radiation).

15. The measurements of optical radiation with a calibrated measuring device, which is suitable for the performance of the measurements of relevant optical radiation in accordance with the manufacturer's instructions for use, shall be performed by:

15.1. the laboratories accredited in the territorial unit of the Metrology and Accreditation State Agency - the National Accreditation Bureau of Latvia - in accordance with the standard LVS EN ISO/IEC 17025:2005 General Requirements for the Testing and Calibration Laboratories;

15.2. other institutions, which are accredited in European Union Member States and are entitled to perform the measurements of optical radiation;

15.3. the competent institutions or competent specialists in the matters of labour protection;

15.4. the labour protection specialists who have acquired the second level higher education in labour protection in accordance with the regulatory enactments regarding training in the matters of labour protection; or

15.5. persons with a qualification appropriate for the performance of the measurements.

16. An employer, when assessing the risk caused by optical radiation, shall pay particular attention to the following factors:

16.1. the level, wavelength range and duration of exposure to a worker;

16.2. the exposure limit values (Annex 1 and 2);

16.3. any effects concerning the safety and health of the workers belonging to particularly sensitive risk groups (including adolescents, pregnant women and women in the period following childbirth);

16.4. any possible effects on workers' health and safety resulting from workplace interactions between optical radiation and photosensitising chemical substances;

16.5. any indirect effects (including temporary blinding, explosion or fire);

16.6. the condition regarding the existence of replacement equipment designed to reduce the levels of exposure to optical radiation;

16.7. the health examination results of workers, as well as information obtained from scientific investigations regarding the effect of optical radiation on the health of workers;

16.8. the interaction of various sources of optical radiation;

16.9. the classification of lasers or other sources of optical radiation, indicated by the manufacturer of the equipment, and the level of hazard associated thereto, in particular taking into account the damage caused by a laser of Class 3B or 4 or other sources of optical radiation of a similar classification (intermediate or high); and,

16.10. other information provided by the manufacturers of optical radiation sources and associated equipment.

17. An employer shall document and store all the results of the assessment of the risk arising from the optical radiation and measurement results for three years. After expiry of the specified period of time the information shall be transferred for storage to the archives.

III. Prevention or Reduction of the Risk Arising from Optical Radiation

18. In assessing or reducing the risk arising from optical radiation, an employer shall observe the general labour protection principles specified in the Labour Protection Law.

19. An employer, in accordance with the requirements specified in the Labour Protection Law, shall consult with workers or trusted representatives thereof regarding the issues that are related to the risk arising from optical radiation in the work environment, as well as creating the opportunity for the participation of workers in the solving of the relevant issues.

20. An employer shall take the necessary measures in accordance with the results of the risk assessment (including organisational measures - reduction of the period of exposure, rest breaks) for the prevention or reduction of the risk arising from optical radiation to the minimum (the lowest practical level) on the basis of technical progress and using the latest means for the control of the risk source arising from optical radiation.

21. If, when performing a risk assessment of the work environment, it is established that the exposure limit values (Annexes 1 and 2) may be exceeded, an employer shall include the following organisational and technical measures to be performed in specific workplaces, in the plan of labour protection measures:

21.1. to use such work methods which reduce the risk caused by optical radiation;

21.2. to select work equipment which has a lower level of exposure to optical radiation, taking into account the work to be performed;

21.3. to perform technical measures for the reduction of the level of exposure to optical radiation, if necessary, installing equipment for the reduction of the level of exposure to optical radiation, including interlocks, shielding or similar mechanisms to ensure the protection of the health of workers;

21.4. to ensure the cleaning and maintenance of the workstation systems and work equipment in accordance with the regulatory enactments regarding the labour protection requirements in workplaces and when using work equipment;

21.5. to optimise the design and layout of workplaces;

21.6. to restrict the duration and level of exposure to optical radiation;

21.7. to ensure workers with appropriate personal protective equipment; and

21.8. to perform measures in accordance with the instructions of the manufacturer of work equipment.

22. In the workplaces referred to in Paragraph 21 of these Regulations an employer shall place the appropriate safety signs in accordance with the regulatory enactments regarding the labour protection requirements for the use of safety signs. The employer shall ensure the delimitation of hazardous zones and restricted access to these zones, if the exposure to risk caused by optical radiation is justified and the restrictions are technically possible.

23. If, after the labour protection measures performed by an employer for the reduction of the risk caused by optical radiation, the exposure limit values are still exceeded, the employer shall:

23.1. perform measures without delay, in order to prevent the exposure of workers to such optical radiation and to reduce the exposure thereof ensuring that it does not exceed the exposure limit values;

23.2. analyse and determine the reasons, due to which the exposure to optical radiation exceeds the exposure limit values; and

23.3. make changes in the labour protection measures in order to prevent the exposure limit values of optical radiation being exceeded again.

24. An employer shall ensure that workers, who are exposed to risks arising from optical radiation in the work place, and their representatives are appropriately trained and receive information in a comprehensible manner regarding:

24.1. the exposure to optical radiation and the potential risk to the safety and health of workers;

24.2. the labour protection measures, which prevent or reduce the effect of the risk arising from optical radiation on the safety and health of workers to the minimum;

24.3. the results which are acquired in the assessment of the risk caused by optical radiation, and the significance thereof;

24.4. the symptoms of the health disorders arising from exposure to optical radiation, the significance of timely detection of health disorders and the action if health disorders have occurred;

24.5. the conditions in which workers have the right to health surveillance, as well as regarding the significance of the mandatory health examination;

24.6. safe work methods, as well as correct and safe use of work equipment in order to prevent or reduce to the minimum the risk caused by optical radiation; and

24.7. correct and appropriate use of personal protective equipment.

IV. Health Examination of Workers

25. If a worker is exposed to the effect of the risk caused by optical radiation, which exceeds the exposure limit values (Annexes 1 and 2), the employer shall ensure the mandatory health examination of the worker in accordance with the regulatory enactments regarding the procedures by which mandatory health examination shall be performed, in order to diagnose the health disorders caused by optical radiation as soon as possible and to ensure qualitative protection of the health of workers.

26. Upon the request the employer shall ensure access to the results of the assessment of risk caused by optical radiation to the worker, the family doctor of the worker and an occupational health doctor, which performs the mandatory health examination of the worker.

27. If such health disorders are established to the worker during the mandatory health examination, which are assessed by the occupational health doctor as the consequences caused by exposure to optical radiation:

27.1. the doctor shall inform the worker regarding the results of his or her health examination and provide recommendations for health care also after the end of exposure to optical radiation, as well as inform the employer regarding the health examination results in accordance with the regulatory enactments regarding the procedures by which mandatory health examination shall be performed;

27.2. the employer shall, without delay, organise the health examination of other workers which have been exposed to similar effects of optical radiation; and

27.3. the employer shall review the risk assessment which has been performed in accordance with Part II of these Regulations, and the measures for the prevention or reduction of risk.

28. The employer shall ensure documentation of the results of health examinations of workers. Upon a justified request of the State Labour Inspectorate the employer shall issue copies of health examination cards.

29. The employer shall take into account the results of health examinations in planning and determining the labour protection measures for the prevention or reduction of the risk arising from optical radiation to the permissible level.

V. Closing Provision

30. These Regulations shall come into force on 27 April 2010.

Informative Reference to European Union Directive

These Regulations contain legal norms arising from Directive 2006/25/EC of the European Parliament and of the Council of 29 April 2004 on the minimum health and safety requirements regarding exposure of workers to the risks arising from physical agents (artificial optical radiation) (19th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC).

Prime Minister,
Minister for Children, Family and
Integration Affairs V. Dombrovskis

Minister of Welfare U. Augulis

 

Revised by the Ministry of Welfare

Annex 1
Cabinet Regulation No. 731
30 June 2009

Determination of the Values of Non-coherent Optical Radiation Effects

1. The biophysically relevant exposure values to optical radiation can be determined with the formulae below:

(a) (Heff is only relevant in the range 180 to 400 nm)
(b) (HUVA is only relevant in the range 315 to 400 nm)
(c),(d) (LB is only relevant in the range 300 to 700 nm)
(e), (f) (EB is only relevant in the range 300 to 700 nm)
(g) to (l) (See Table 1.1 for appropriate values of λ1 and λ2)
(m), (n) (EIS is only relevant in the range 780 to 3000 nm)
  (Hādai is only relevant in the range 380 to 3000 nm)

where

Eλ(λ,t), Eλ spectral irradiance or spectral power density: the radiant power incident per unit area upon a surface, expressed in watts per square metre per nanometre (W/m2 x nm); values of Eλ (λ, t) un Eλ come from measurements or may be provided by the manufacturer of the equipment;

Eeff effective irradiance (UV range): calculated irradiance within the UV wavelength range 180 to 400 nm spectrally weighted, expressed in watts per square metre (W/m2);

H radiant exposure: the time integral of the irradiance, expressed in joules per square metre (J/m2);

Heff effective radiant exposure: radiant exposure spectrally weighted by S (λ), expressed in joules per square metre (J/m2);

EUVA total irradiance (UVA): calculated irradiance within the UVA wavelength range 315 to 400 nm, expressed in watts per square metre (W/m2);

HUVA radiant exposure: the time and wavelength integral or sum of the irradiance within the UVA wavelength range 315 to 400 nm, expressed in joules per square metre (J/m2);

S (λ) spectral weighting taking into account the wavelength dependence of the health effects of UV radiation on eye and skin (Table 1.2) (dimensionless);

t, Δt time, duration of the exposure, expressed in seconds (s);

λ wavelength expressed in nanometres (nm);

Δ λ bandwidth, expressed in nanometres (nm), of the calculation or measurement intervals;

Lλ (λ), Lλ spectral radiance of the source, expressed in watts per square metre per steradian per nanometre (W/m2 x sr x nm);

R (λ) spectral weighting taking into account the wavelength dependence of the thermal injury caused to the by visible and IRA radiation (Table 1.3) (dimensionless);

LR effective radiance (thermal injury): calculated radiance spectrally weighted by R (λ) expressed in watts per square metre per steradian (W/m2 x sr);

B (λ) spectral weighting taking into account the wavelength dependence of the photochemical injury caused to the eye by blue light radiation (Table 1.3) (dimensionless);

LB effective radiance (blue light): calculated radiance spectrally weighted by B (λ) expressed in watts per square metre per steradian (W/m2 x sr);

EB effective irradiance (blue light): calculated irradiance spectrally weighted by B (λ) expressed in watts per square metre (W/m2);

EIS total irradiance (thermal injury): calculated irradiance within the infrared wavelength range 780 to 3 000 nm, expressed in watts per square metre (W/m2);

Eskin total irradiance (visible, IRA and IRB): calculated irradiance within the visible and infrared wavelength range 380 to 3000 nm, expressed in watts per square metre (W/m2);

Hskin radiant exposure: the time and wavelength integral or sum of the irradiance within the visible and infrared wavelength range 380 to 3 000 nm, expressed in joules per square metre (J/m2);

α angular subtense: the angle subtended by an apparent source, as viewed at a point in space, expressed in milliradians (mrad). Apparent source is the real or virtual object that forms the smallest possible retinal image.

2. The aforementioned formulae may be replaced by the following expressions and discrete values:

(a)
(b)
(c),(d)
(e), (f)
(g) to (l)   See 1.1. Table 1.1 in relation to λ1 and λ2
(m), (n)  
(o)

Notes:

1. The formulae to be used depend on the range of radiation caused by the relevant source, and the results shall be compared with the respective exposure limit values indicated in Table 1.1.

2. More than one exposure value and the corresponding exposure limit value thereof may correspond to one source of optical radiation.

3. Indices a) to o) correspond to the respective rows in Table 1.1.

Table 1.1

Exposure Limit Values for Non-coherent Optical Radiation

Index Wavelength (nm) Exposure limit value Unit of measurement Notes Part of the body Hazard
a. 180-400
(UVA, UVB and UVC)

 

Heff = 30
Daily value 8 hours
[J/m2]   eye cornea
conjunctiva
lens
skin
photokeratitis
conjunctivitis
cataractogenesis
erythema
elastosis
skin cancer
b. 315-400
(UVA)
HUVA = 104
Daily value 8 hours
[J/m2]   Eye lens cataractogenesis
c. 300-700
(Blue light) See Note 1
LB= 106
t

for t ≤ 10000 s

LB: [W/m2 x sr]

t: [seconds]

for α ≥ 11 mrad Eye retina photoretinitis
d. 300-700
(Blue light) See Note 1
LB = 100

for t > 10000 s

[W/m2 x sr]
e. 300-700
(Blue light) See Note 1
EB= 100
t

for t ≤ 10000 s

EB: (W/m2)

t: [seconds]

for α < 11 mrad

See Note 2

f. 300-700
(Blue light)
See Note 1
EB = 0,01

t >10 000 s

[W/m2]
g. 380-1400
(Visible and IRA)
LR= 2,8 × 107
Cα

for t > 10 s

[W/m2 x sr]

 

Cα = 1,7 for

α ≤ 1.7 mrad

Cα = α for

1.7 ≤ α ≤ 100 mrad

Cα= 100 for

α > 100 mrad

λ1= 380; λ2= 1400

Eye retina Retinal burn
h. 380-1400

(Visible and IRA)

 

LR= 5 × 107
Cαt0,25

for 10 µs ≤ t ≤ 10 s

LR: [W/m2 x sr]

t: [seconds]

i. 380-1400
(Visible and IRA)

 

LR= 8,89 × 108
Cα

for t < 10 µs

[W/m2 x sr]
j. 780-1400
(IRA)

 

LR= 6 × 106
Cα

for t > 10 s

[W/m2 x sr] Cα = 11 for

α ≤ 11 mrad

Cα = α for

11 ≤ α ≤ 100 mrad

Cα= 100 for

α > 100 mrad

(measurement field-of-view) 11 mrad)

λ1= 780; λ2= 1400

Eye retina Retinal burn
(k) 780-1400
(IRA)

 

LR= 5 × 107
Cαt0,25

for 10 µs ≤ t ≤ 10 s

LR: [W/m2 × sr]

t [seconds]

l. 780-1400

(IRA)

LR= 8,89 × 108
Cα

for t < 10 µs

[W/m2 × sr]
m. 780-3000
(IRA and IRB)
EIR = 18000t0,75

for t ≤ 1 000 s

E: [W/m2]

t: [seconds]

  eye cornea

lens

Corneal burn

cataractogenesis

n. 780-3000
(IRA and IRB)
EIR = 100

for t> 1000 s

[W/m2]    
o. 380-3000
(visible, IRA and IRB)
Hskin = 20000 t0,25

for t > 10 s

H: [J/m2]

t: [seconds]

  skin burn

Notes:

1. The range of 300 to 700 nm covers part of UVB, all UVA and most of visible radiation; however the associated hazard is commonly referred to as "blue light" hazard. Blue light, strictly speaking, covers only the range of approximately 400 to 490 nm.

2. For steady fixation of very small sources with an angular subtense < 11 mrad, LB can be converted to EB. This normally applies only for ophthalmic instruments or a stabilised eye during anaesthesia. The maximum "stare time" is found by: tmax = 100/EB with EB expressed in W/m2. Due to eye movements during normal visual tasks this does not exceed 100 s.

Table 1.2

S (λ) (dimensionless), 180 nm to 400 nm

λ in nm S (λ) λ in nm S (λ) λ in nm S (λ) λ in nm S (λ) λ in nm S (λ)
180 0,0120 228 0,1737 276 0,9434 324 0,000520 372 0,000086
181 0,0126 229 0,1819 277 0,9272 325 0,000500 373 0,000083
182 0,0132 230 0,1900 278 0,9112 326 0,000479 374 0,000080
183 0,0138 231 0,1995 279 0,8954 327 0,000459 375 0,000077
184 0,0144 232 0,2089 280 0,8800 328 0,000440 376 0,000074
185 0,0151 233 0,2188 281 0,8568 329 0,000425 377 0,000072
186 0,0158 234 0,2292 282 0,8342 330 0,000410 378 0,000069
187 0,0166 235 0,2400 283 0,8122 331 0,000396 379 0,000066
188 0,0173 236 0,2510 284 0,7908 332 0,000383 380 0,000064
189 0,0181 237 0,2624 285 0,7700 333 0,000370 381 0,000062
190 0,0190 238 0,2744 286 0,7420 334 0,000355 382 0,000059
191 0,0199 239 0,2869 287 0,7151 335 0,000340 383 0,000057
192 0,0208 240 0,3000 288 0,6891 336 0,000327 384 0,000055
193 0,0218 241 0,3111 289 0,6641 337 0,000315 385 0,000053
194 0,0228 242 0,3227 290 0,6400 338 0,000303 386 0,000051
195 0,0239 243 0,3347 291 0,6186 339 0,000291 387 0,000049
196 0,0250 244 0,3471 292 0,5980 340 0,000280 388 0,000047
197 0,0262 245 0,3600 293 0,5780 341 0,000271 389 0,000046
198 0,0274 246 0,3730 294 0,5587 342 0,000263 390 0,000044
199 0,0287 247 0,3865 295 0,5400 343 0,000255 391 0,000042
200 0,0300 248 0,4005 296 0,4984 344 0,000248 392 0,000041
201 0,0334 249 0,4150 297 0,4600 345 0,000240 393 0,000039
202 0,0371 250 0,4300 298 0,3989 346 0,000231 394 0,000037
203 0,0412 251 0,4465 299 0,3459 347 0,000223 395 0,000036
204 0,0459 252 0,4637 300 0,3000 348 0,000215 396 0,000035
205 0,0510 253 0,4815 301 0,2210 349 0,000207 397 0,000033
206 0,0551 254 0,5000 302 0,1629 350 0,000200 398 0,000032
207 0,0595 255 0,5200 303 0,1200 351 0,000191 399 0,000031
208 0,0643 256 0,5437 304 0,0849 352 0,000183 400 0,000030
209 0,0694 257 0,5685 305 0,0600 353 0,000175    
210 0,0750 258 0,5945 306 0,0454 354 0,000167    
211 0,0786 259 0,6216 307 0,0344 355 0,000160    
212 0,0824 260 0,6500 308 0,0260 356 0,000153    
213 0,0864 261 0,6792 309 0,0197 357 0,000147    
214 0,0906 262 0,7098 310 0,0150 358 0,000141    
215 0,0950 263 0,7417 311 0,0111 359 0,000136    
216 0,0995 264 0,7751 312 0,0081 360 0,000130    
217 0,1043 265 0,8100 313 0,0060 361 0,000126    
218 0,1093 266 0,8449 314 0,0042 362 0,000122    
219 0,1145 267 0,8812 315 0,0030 363 0,000118    
220 0,1200 268 0,9192 316 0,0024 364 0,000114    
221 0,1257 269 0,9587 317 0,0020 365 0,000110    
222 0,1316 270 1,0000 318 0,0016 366 0,000106    
223 0,1378 271 0,9919 319 0,0012 367 0,000103    
224 0,1444 272 0,9838 320 0,0010 368 0,000099    
225 0,1500 273 0,9758 321 0,000819 369 0,000096    
226 0,1583 274 0,9679 322 0,000670 370 0,000093    
227 0,1658 275 0,9600 323 0,000540 371 0,000090    

Table 1.3

B (λ), R (λ) (dimensionless), 380 nm to 1 400 nm

λ in nm B (λ) R (λ)
300 ≤ λ <380 0,01 -
380 0,01 0,1
385 0,013 0,13
390 0,025 0,25
395 0,05 0,5
400 0,1 1
405 0,2 2
410 0,4 4
415 0,8 8
420 0,9 9
425 0,95 9,5
430 0,98 9,8
435 1 10
440 1 10
445 0,97 9,7
450 0,94 9,4
455 0,9 9
460 0,8 8
465 0,7 7
470 0,62 6,2
475 0,55 5,5
480 0,45 4,5
485 0,32 3,2
490 0,22 2,2
495 0,16 1,6
500 0,1 1
500 < λ ≤ 600 100,02.(450-λ) 1
600 < λ ≤ 700 0,001 1
700 < λ ≤ 1050 - 1000.002.(700-λ)
1050 < λ ≤ 1150 - 0,2
1150 < λ ≤ 1200 - 0,2 x 10 0,02x(1150-λ)
1200 < λ ≤ 1400 - 0,02

Minister of Welfare U. Augulis

 

Annex 2
Cabinet Regulation No.731
30 June 2009

Determination of the Exposure Value of Laser Optical Radiation

The biophysically relevant exposure values to optical radiation can be determined with the formulae below:

E= dP  
dA
(W/(m2)
[J/m2]

where

dP power, expressed in watts (W);

dA surface, expressed in square metres (m2);

E (t), E irradiance or power density: the radiant power incident per unit area upon a surface, generally expressed in watts per square meter (W/m2). Values of E(t) and E come from measurements or may be provided by the manufacturer of the equipment;

H radiant exposure: the time integral of the irradiance, expressed in joules per square metre (J/m2);

T time, duration of the exposure, expressed in seconds (s);

λ wavelength expressed in nanometres (nm);

γ limiting cone angle of measurement, expressed in milliradians (mrad);

γm measurement field of view, expressed in milliradians (mrad);

α angular subtense of a source, expressed in milliradians (mrad);

limiting aperture: the circular area over which irradiance and radiant exposure are averaged;

G integrated radiance: the integral of the radiance over a given exposure time expressed as radiant energy per unit area of a radiating surface per unit solid angle of emission, in joules per square metre per steradian (J/m2 sr).

Notes:

1. The formulae to be used depend on the wavelength and duration of radiation emitted by the source and the results should be compared with the corresponding exposure limit values indicated in Tables 2.2 to 2.4.

2. More than one exposure value or effect value can be relevant for a given source of laser optical radiation, for example, the wavelength may be changed for sources and they may have different exposure times. In each case the respective exposure limit value should be applied.

3. Parameters and corrective values which are used for calculations in Tables 2.2 to 2.4 are provided in Table 2.5 and the application thereof for repeat exposure is listed in Table 2.6.

Table 2.1

Laser Radiation Hazards

Wavelength
λ, nm
Radiation range Affected organ Hazard Exposure limit value
180 to 400 UV eye photochemical damage and thermal damage 2.2, 2.3
180 to 400 UV skin erythema 2.4
400 to 700 visible eye retinal damage 2.2
400 to 600 visible eye photochemical damage 2.3
400 to 700 visible skin thermal damage 2.4
700 to 1400 IRA eye thermal damage 2.2, 2.3
700 to 1400 IRA skin thermal damage 2.4
1400 to 2600 IRB eye thermal damage 2.2
2600 to 106 IRC eye thermal damage 2.2
1400 to 106 IRB, IRC eye thermal damage 2.3
1400 to 106 IRB, IRC skin thermal damage 2.4

Table 2.2

Exposure Limit Values for Laser Exposure to the Eye. Short Exposure Duration < 10 s

Wavelength1 (nm) Aperture Duration (s)
10-13 - 10-11 10-11 - 10-9 10-9 - 10-7 10-7 - 1,8 · 10-5 1,8 · 10-5-
5 · 10-5
5 · 10-5 - 10-3 10-3 - 101
UVC 180-280

1 mm for t<0,3 s; 1,5 t0.375 for 0,3<t<10 s

H = 30 (J/m2)
UVB 280-302
303 H = 40 [J/m2]; if t < 2,6 · 10-9, then H = 5,6 · 103 t 0,25 [J/m2] See

Note 4

304 H = 60 [J/m2]; if t < 1,3 · 10-8, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
305 H = 100 [J/m2]; if t < 1,0 · 10-7, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
306 H = 160 [J/m2]; if t < 6,7 · 10-7, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
307 H = 250 [J/m2]; if t < 4,0 · 10-6, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
308 H = 400 [J/m2]; if t < 2,6 · 10-5, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
309 H = 630 [J/m2]; if t < 1,6 · 10-4, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
310 H = 103 [J/m2]; if t < 1,0 · 10-3, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
311 H = 1,6 103 [J/m2]; if t < 6,7 · 10-3, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
312 H = 2,5 103 [J/m2]; if t < 4,0 · 10-2, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
313 H = 4,0 103 [J/m2]; if t < 2,6 · 10-1, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
314 H = 6,3 103 [J/m2]; if t < 1,6 · 100, then H = 5,6 · 103 t 0,25 [J/m2] See Note 4
UVA 315-400 H = 5,6 · 103 t 0,25 [J/m2]
Visible and IRA 400-700 7 mm H = 1,5 · 10-4 CE
[J/m2]
H = 2,7 · 104 t 0,75 CE
[J/m2]
H = 5 · 10-3 CE [J/m2] H = 18 · t 0,75 CE [J/m2]
700-1050 H = 1,5 · 10-4 CA CE [J/m2] H=2,7 · 104 t 0,75 CA CE 
[J/m2]
H = 5 · 10-3 CA CE [J/m2] H = 18 · t 0,75 CA CE [J/m2]
1050-1400 H = 1,5 · 10-3 CC CE [J/m2] H =2,7 · 105 t 0,75 CC CE
[J/m2]
H = 5 · 10-2 CC CE [J/m2] H = 90 · t 0,75 CC CE ([J/m2]
IRB
and
IRC
1400-1500

See Note 2

E = 1012 [W/m2] See Note 3 H = 103 (J/m2) H = 5.6 . 103 . t0,25 (J/m2)
1500-1800 E = 1013 [W/m2] See Note 3 H = 104 [J/m2]
1800-2600 E = 1012 [W/m2] See Note 3 H = 103 [J/m2] H = 5,6 ·103 · t 0,25 [J/m2]
2600-10 6 E = 1011 [W/m2] See Note 3 H=100 [J/m2] H = 5,6 · 103 · t 0,25 [J/m2]

Notes:

1. If the wavelength of the laser is covered by two limits, then the more restrictive applies.

2. When 1400 ≤ λ<105 nm: aperture diameter = 1 mm for t ≤ 0,3 s and 1,5 t0,375 mm for 0,3 s < t < 10 s; if 105 ≤ λ<106 nm: aperture diameter = 11 mm.

3. Due to lack of data at these pulse lengths, the International Commission on Non-ionizing Radiation Protection (hereinafter - ICNIRP) recommends the use of 1 ns irradiance limits.

4. The table states values for single laser pulses. In case of multiple laser pulses, then the laser pulse duration of pulses falling within an interval Tmin (listed in Table 2.6) must be added up and the resulting time value must be filled in for t in the formula: 5,6 103 t0,25

Table 2.3

Exposure Limit Values for Laser Exposure to the Eye. Long Exposure Duration > 10 s

Wavelength1 (nm) Aperture Duration (s)
101 - 102 102 - 104 104 - 3 · 104
UVC 180-280   H = 30 (J/m2)
  280-302 3.5 mm
UVB 303 H = 40 (J/m2)
304 H = 60 (J/m2)
305 H = 100 (J/m2)
306 H = 160 (J/m2)
307 H = 250 (J/m2)
308 H = 400 (J/m2)
309 H = 630 (J/m2)
310 H = 1.0 103 (J/m2)
311 H = 1.6 103 (J/m2)
312 H = 2.5 103 (J/m2)
313 H = 4.0 103 (J/m2)
314 H = 6.3 103 (J/m2)
UVA 315-400 H = 104 (J/m2)
Visible
400 - 700
400-600
Photochemical/ retinal damage
See Note 2
7 mm H = 100 CB [J/m2]
(γ = 11 mrad) See Note 4
E = 1 CB [W/m2]; (γ = 1,1 t0,5 mrad)
See Note 4
E = 1 CB [W/m2]
(γ = 110 mrad) See Note 4
Thermal/ retinal damage
See Note 2
if α < 1,5 mrad then E = 10 [W/m2]

if α > 1,5 mrad and t ≤ T2 then H = 18 CE t0,75 [J/m2]

if α > 1,5 mrad and t > T2 then E = 18 CE T2-0,25 [W/m2]

IRA 700-1400 7 mm if α < 1,5 mrad then E = 10 [W/m2]

if α > 1,5 mrad and t ≤ T2 then H = 18 CA CC CE t0,75 [J/m2]

if α > 1,5 mrad and t > T2 then E = 18 CA CC CE T2-0,25 [W/m2] (not to exceed 1000 W/m2)

IRB and IRC 1400-106 See Note 3 E = 1000 [W/m2]

Notes:

1. If the wavelength or another condition of the laser is covered by two limits, then the more restrictive applies.

2. For small sources subtending an angle of 1,5 mrad or less, the visible dual limits E from 400 nm to 600 nm reduce to the thermal limits for 10 s< t <T1 and to photochemical limits for longer times. For T1 and T2 see 2.5. Table 2.5. The photochemical retinal hazard limit may also be expressed as a time integrated radiance G = 106 CB [J/m2 × sr] for t > 10s up to t = 10000 s and L = 100 CB [W/m2 x sr] for t > 10000 s. For the measurement of G and L ym must be used as averaging field of view. The official border between visible and infrared is 780 nm as defined by the International Commission on Illumination (hereinafter - CIE). The column with wavelength band names is only meant to provide better overview for the user. The notation G is used by the European Committee for Standardisation (hereinafter - CEN); the notation Lt is used by CIE; the notation Lp is used by IEC and the European Committee for Electrotechnical Standardization (hereinafter - CENELEC).

3. Wavelength 1400-105 nm: aperture diameter = 3,5 mm; wavelength 105 - 106 nm: aperture diameter = 11 mm.

4. For measurement of the exposure value the consideration of γ is defined as follows: If α (angular subtense of a source) > γ (limiting cone angle, indicated in brackets in the corresponding column) then the measurement field of view γm should be the given value of γ. If a larger measurement field of view is used then the hazard would be overestimated. If α < γ then the measurement field of view γm must be large enough to fully enclose the source but is otherwise not limited and may be larger than γ.

Table 2.4

Exposure Limit Values for Laser Exposure of Skin

Wavelength (nm) Aperture Duration (s)
< 10-9 10-9 - 10-7 10-7 - 10-3 10-3 - 101 101 - 103 103 - 3 · 104
UV
(A, B, C)
180-400 3. 5mm E = 3 . 1010 [W/m2] Same as eye exposure limits
Visible and IRA 400-700 3. 5mm E = 2 . 1011 [W/m2] H=200 CA

[J/m2]

H = 1,1 . 104 CA t0,25

[J/m2]

E = 2 . 103 CA [W/m2]
700-1400 E = 2 · 1011 CA [W/m2]
IRB and IRC 1400-1500 E = 1012 [W/m2] Same as eye exposure limits
1500-1800 E = 1013 [W/m2]
1800-2600 E = 1012 [W/m2]
2600-106 E = 1011 [W/m2]

Note.

If the wavelength or another condition of the laser is covered by two limits, then the more restrictive applies.

Table 2.5

Parameters and Correction Factors for the Determination of Laser Radiation Exposure Limit Values

 1. Parameter as listed in ICNIRP Valid spectral range (nm) Correction value
1.1. CA λ<700 CA = 1,0
700-1050 CA=100,002(λ - 700)
1050-1400 CA = 5,0
1.2. CB 400-450 CB = 1,0
450-700 CB = 10 0,02(λ - 450)
1.3. CC 700-1150 CC=1,0
1150-1200 CC=10 0,018(λ - 1150)
1200-1400 CC=8,0
1.4. T1 λ<450 T1=10 s
450-500 T1 = 10 . [100,02(λ -450)] s
λ>500 T1=100 s
 2. Parameter as listed in ICNIRP Valid for biological effect Correction value
2.1. αmin All thermal effects αmin = 1,5 mrad
 3. Parameter as listed in ICNIRP Valid angular range (mrad) Correction value
3.1. CE α<αmin CE=1,0
αmin<α<100 CE = α/αmin
α>100 CE2min . αmax) mrad with αmax=100 mrad
3.2. T2 α<1,5 T2=10 s
1,5<α<100 T2=10 . (10(α-1,5)/98,5) s
α>100 T2=100 s
 4. Parameter as listed in ICNIRP Valid exposure time range Correction value
4.1. γ t< 100 γ=11 [mrad]
100<t<104 γ = 1,1 t0,5 [mrad]
t>104 γ=11 [mrad]

Table 2.6

Correction for Repetitive Exposure

Each of the following three general rules should be applied to all repetitive exposures as occur from repetitively pulsed or scanning laser systems:

1. The exposure from any single pulse in a train of pulses shall not exceed the exposure limit value for a single pulse of that pulse duration.

2. The exposure from any group of pulses (or sub-group of pulses in a train) delivered in time t shall not exceed the exposure limit value for time t.

3. The exposure from any single pulse within a group of pulses shall not exceed the single-pulse exposure limit value multiplied by a cumulative-thermal correction factor Cp=N-0,25, where N is the number of pulses. This rule applies only to exposure limits to protect against thermal injury, where all pulses delivered in less than Tmin are treated as a single pulse.

Parameter Valid spectral range (nm) Correction value
Tmin 315<λ< 400 Tmin = 10-9 s (= 1 ns)
400<λ< 1050 1050 Tmin = 18 · 10-6 s (= 18 µs)
1050 <λ<1400 1400 Tmin = 50 · 10-6 s (= 50 µs)
1400<λ< 1500 1500 Tmin = 10-3 s (= 1 ms)
1500<λ< 1800 1800 Tmin = 10 s
1800<λ< 2600 2600 Tmin = 10-3 s (= 1 ms)
2600<λ< 106 10 6 Tmin = 10-7 s (= 100 ns)

Minister of Welfare U. Augulis

 


Translation © 2010 Valsts valodas centrs (State Language Centre)

 
Document information
Title: Darba aizsardzības prasības nodarbināto aizsardzībai pret mākslīgā optiskā starojuma radīto .. Status:
In force
in force
Issuer: Cabinet of Ministers Type: regulation Document number: 731Adoption: 30.06.2009.Entry into force: 27.04.2010.Publication: Latvijas Vēstnesis, 105, 07.07.2009.
Language:
LVEN
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