January 29, 2004
Several technical articles have addressed respiratory diseases associated with welding activities and when a respirator should be used to help prevent these diseases. Once an employer concludes that respiratory protection is the appropriate option for a particular application, the next step is selecting the right respirator.
Several factors can help employers select a respirator that meets the required level of protection while having a positive business impact. Using this approach, employers can make choosing a respirator a business decision that can increase productivity, decrease injuries, and decrease employee turnover.
For any welding or grinding application, an array of respirators can offer an appropriate level of protection. The unit cost of those respirators may range from $1 for a basic disposable respirator to $1,000 or more for a positive-pressure system. But the initial price is only one part of the equation, and other cost issues must be considered:
Reusable respirators may last longer but they require daily cleaning and maintenance — a labor cost that can add up. Depending on the respirator, maintenance may include washing, filter changing, battery charging, inspection, and component replacement.
Depending on job conditions, disposable respirators, also known as dust masks, can get clogged or too grimy to last through one work shift. In these cases, the long-term cost of frequent respirator replacement can negate the low unit cost advantage of disposables.
Training requirements and costs for maintenance of respirators vary depending on the respirator selected. Will all respirator users be trained to maintain their personal respirators, or will maintenance personnel be designated for the job?
Note about assigned protection factors: Assigned protection factors (APF) are an estimate of the level of protection provided by a particular respirator when used properly. For example, an APF of 10 means for every 10 parts of contaminant in the atmosphere, a maximum of up to 1 part can be expected to enter the breathing zone of the wearer. Another way to describe APFs is that a respirator with an APF of 10 can be used in an atmosphere containing airborne contaminants up to 10 times the exposure limit. APFs are applicable only when the respirator is properly fit-tested, the appropriate cartridge or filter is selected, and the user follows all instructions.
Heat stress is a common problem with welding and other metal fabrication operations. For many, it's a daily issue. This can result in reduced productivity, reduced quality, and higher employee turnover.
Factors that can contribute to heat stress include:
When heat stress is an issue, the last thing welders want is a respirator strapped to their face. In response, many employers are turning to positive-pressure respirator systems that incorporate vortex cooling technology.
Through these belt-mounted systems, breathing-quality air is supplied to the device from a remote compressor via an air hose. By spinning the air at high speeds, the vortex device uses centrifugal force to divide the air into two separate airstreams, one hot and one cold. In the process, the desired stream—usually the cold—is reduced to the appropriate pressure and flow rate and delivered to the respirator headpiece. In this manner, the air temperature entering the headpiece can be lowered by up to 50 degrees F by means of a control valve on the device.
Another type of positive-pressure respirator, the powered air-purifying respirator (PAPR), uses a belt-mounted battery to force air through a filter and into the headgear. Even though these systems can't cool the air, the constant movement of air across the user's face can have a cooling effect.
Providing respirators that add comfort instead of discomfort can make a huge difference in employee morale. And happy workers who stay on the job longer mean higher productivity, higher quality, less recruitment, and less retraining.
Although the employer ultimately is responsible for choosing which respirator options to make available, many of the considerations will become secondary to the preferences of the welders who will be wearing the respirator.
Clifford Frey is a certified industrial hygienist and a senior technical service representative for 3M's Occupational Health & Environmental Safety Division, 3M Center, Building 235-2E-91, St. Paul, MN 55144, 800-3M-HELPS, fax 605-432-9406, firstname.lastname@example.org, www.mmm.com.
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