Tag: radiation hazards

General radiation hazard information

Found: “Class 2” laser pointers not as advertised

Click here to view a PDF write-up of the incident.

An academic department turned over two green laser presenters labeled “Class 2″ to the Homewood Laser Safety Advocate for evaluation because one seemed “too bright.” Normally, a Class 2 laser presentation pointer should put out no more than 1 milliwatt of energy.

Both presenters were found to be putting out more than 10 times the allowable amount of energy, including energy in the invisible infrared range, which is more dangerous. (Green laser pointers are actually infrared lasers that use special optics to generate green light from the IR.) The Laser Safety Advocate tested several additional pointers from that department, finding them all in conformance with their markings. The overpowered pointers were disposed.

The overpowered pointers were actually hazardous Class 3B lasers which should not be used in an uncontrolled lecture or presentation setting. Homewood limits the power of laser pointers to Class 2; testing has shown that brighter pointers are not necessary in any lecture hall on campus. The class of a laser device is stamped on a small yellow or white sticker on the product.

These were name-brand laser pointers purchased from nonstandard sources (e.g., online auction sites); we are as yet unsure whether they were genuine branded products that are off-specification or if they were counterfeit. Please buy all laser pointers from standard JHU-approved sources such as Office Depot; unusual distribution channels are more likely to sell counterfeit or otherwise out-of-specification products. A sample of the sample laser presenter purchased from a JHU-preferred vendor measured within normal safe tolerances.

In 2013, the National Institute of Standards and Technology (NIST) found that 90% of green laser pointers and 44% of red laser pointers were out of compliance with federal safety regulations and their markings.

If you have a laser pointer that seems too bright, especially if it is green, contact the Homewood Laser Safety Advocate, Niel Leon, [email protected]. He can test your laser pointer and return it to you if it is safe to use (or help you find a source for a safe one if it’s not).

See the HSE Guidance Document on laser pointers, as well as this fact sheet(Laser pointer fact sheet v9-170725FNL), for more details.

Unattended experiments

Some experiments take time: hours, days, even weeks. This means that the experiment will be set up and running in the lab while you are not there. You have an ethical obligation to prevent harm to others in the lab by ensuring that they are aware of your experiment and its hazards. Make sure they know:

  • What the purpose of the experiment is;
  • To whom it belongs;
  • What behavior indicates that something has gone wrong; and
  • What to do if something does go wrong.

You could tell the members of the lab all that information, but some lab members might not be present and others will promptly forget. Depending on the lab’s occupants to “know what’s going on” is foolish—your colleagues may know the general type of research you do but they are not familiar with the details of all your experiments. Far better is to post the information so that anyone in the lab can easily see what your experiment is, how to identify abnormal situations, and what to do in that event.

A sample form is available for you to use directly or adapt to your lab’s needs. (The file is in Word format for easy modification.) The form is written to allow use in teaching as well as research labs. You should prepare two copies of the form: one to post near the experimental apparatus and one to post in a safe place (like on the door). In an emergency, no one may be willing to approach the apparatus to read the information sheet!

Protect your eyes from high-intensity light

Protect your vision when working with UV germicidal lamps; lasers; welding and arc lamps; or other high–energy light sources. Special goggles limit the amount of light that can reach your eyes and skin. The type and amount of protection depends on the frequency, nature, and intensity of light. Learn more in Light eye protection.

What eye protection do I use?

There are many different types of protective eyewear available, and each one is designed to protect against a different hazard. Having the wrong type of safety eyewear can be worse than not wearing eye protection at all. Learn about the basic types in Choosing eye protection.

This Hopkins Safety Note is the start of a series on eye protection, so look for future notes covering the different types in detail.