First line of defence in the workplace engineering controls
Even low-power lasers can be a hazard for pilots, drivers or heavy machinery operators when pointed into their eyes, especially in the dark, according to Nikolay Stoev, president of Valkom Laser Consulting in Toronto.
"The associated visual effects — glare, flash blindness, etc. (although temporary and non-injurious) — can occur even at levels well below the applicable MPE (maximum permissible exposures) for the respective wavelengths."
And while high-tech equipment could help in this situation, it doesn’t provide 100 per cent protection, he said.
"There are some goggles that can be switched on to block some of these (lasers) but unfortunately you cannot know beforehand which wavelength or which colour will be (involved)."
Lasers can pose risks when not used properly, and workplace safety should be a high priority.
"Lasers are increasing in use because they provide some capabilities that are not easily achieved by other means, so they provide more accuracy, solving sometimes difficult tasks," said Stoev.
There are three major laser safety standards in the world: the U.S. Federal Laser Product Performance Standard enforced by the Food and Drug Administration (FDA); the International Laser Safety Standard IEC 60825-1 (these apply to manufacturers of laser products); and the ANSI Z136 standard published by the American National Standards Institute (these apply to users of lasers and laser systems in various conditions or applications). In Canada, regulations differ among the provinces but most refer to the ANSI standard, he said.
Lasers are classified into four classes and subclasses: class 1 and 1M, class 2 and 2M, 3R and 3B, and class 4.
Classes 1 and 2 are effectively not considered hazardous and can’t do damage even if a person looks directly into the beam, such as a CD player or supermarket scanner, he said. It’s only class 3b and 4 that are higher risks, said Richard Colwell, occupational and research safety associate, risk management services, at the University of British Columbia in Vancouver.
If a laser reaches a person for an extended period, it can cause extensive damage, said Kevin Harris, project manager at engineering firm ProSafe in Stratford, Ont. Even one second of hitting the right spot on the retina could scar the back of it. And workers using a laser to weld materials such as metal could face physical injury as well.
"If you’re burning something or taking that laser to it, then whatever’s coming off of that, the exhaust or whatever, could possibly be a contaminant," he said.
Protection from lasers in the workplace starts with engineering controls — that’s your first line of defence, according to Harris. That means having a laser safety officer who knows the hazards and how to mitigate those hazards, performs a risk analysis on installations and determines what safeguards need to be in place.
The best way to protect employees is to have the laser beam access eliminated completely or minimized as much as possible through enclosure or isolation, said Stoev. If that’s not possible, the second level of protection is procedural controls, so standing operating procedure with a detailed list of associated hazards and control measures.
Personal protective equipment can be used, such as eye goggles or face shields, but this should be the last line of protection, he said. Lab coats and creams can also provide skin protection for scattered or stray UV radiation, though these are not always necessary as it depends on the frequency and length of the exposure.
There could also be a need for ventilation or filtration for possible contaminants, said Harris. And with larger lasers, the control system and power modulator can run at a higher frequency so people with a pacemaker are often cautioned because of the frequencies and electromagnetic field, he said. But protective equipment is only effective when you’re talking about reflective radiation — if you stick your eye in a class 4 beam, goggles won’t do much, said Colwell
"When you’re talking about a class 3b or 4 laser, even if you’ve got the safety goggles, which are a proper optical density for the wavelength and the beam divergence, there’s a big calculation that you have to get into, and different laser goggles are rated at different optical densities," he said. "Goggles, any kind of skin protection, like gloves or anything like that, those things are very effective at protecting the users but really, in my opinion, education and awareness are key for employees to protect themselves."