1. (1 pt). A worker in a cast iron foundry must collect samples of molten metal (T=1480^oC). The process involves being about 4 feet from the source and takes 5 minutes. The worker repeats this task 3 times per shift. Measured irradiance (E_IR-only) in W/cm² were made in the IR-A (770 nm-1400 nm ) and IR-B (1400 nm-3000 nm) ranges. The measured values are IR-A: 0.3 W/cm² and IR-B: 1.03 W/cm². Does this exposure exceed the TLV set to protect against thermal injury to the cornea and lens from IR radiation?

2. (3 pt). Exposure description: In the hospital pharmacy, two nurses were accidentally exposed to ultraviolet radiation during preparation of drugs. This operation took about an hour of continuous work and was carried out under the laminar flow hood, whereas the UVC germicidal lamp, instead of the supplied fluorescent neon, was mistakenly turned on. The laboratory unit has a glass shield, but that was incorrectly kept open by the operators during the drug preparation. Exposure reconstruction was conducted with the following assumptions.

Exposure duration 60 min

Eye and face skin are the areas for concern (gloves were used and likely attenuated the UV-C beam)

For eye exposure, assumed the nurses looked toward the source 50% of the time (1800 s) and remaining time were looking at the back of the hood (900 s) and the work surface (900 s) where the exposure would be reflected from those surfaces.

Effective irradiance was measured directly with a UV radiometer that mimics the relative spectral effectiveness of Table 1 and Figure 2 of the TLV.

Measurement results are shown here:

Spectral Band	Organ	Detector Directions	Eeff (W/m2)	Exposure Time (s)
UV-C	Eyes	Source	1.68	1800
		Visual task (toward back of hood)	0.805	900
		Work surface	0.207	900
	Skin	Source	1.68	3600
UV-B	Eyes	Source	0.024	1800
		Visual task (toward back of hood)	0.011	900
		Work surface	0.003	900
	Skin	Source	0.024	3600

Does the eye exposure exceed the TLV?

Does the skin exposure exceed the TLV?

3. (1 pt). You have a laboratory measurement of UV irradiance from CO₂ arc welding equal to 7.1 W/m², at 1 m. You need to select eye protection to reduce this irradiance to an 8 hr exposure of 30 J/m². What is the minimum shade # that you can use to meet this requirement?