By Kent Hatcher, CPE and Jeff Sanford, CPE
Thanks to those of you who attended last week’s webinar, “Material Handling Methods: Risk Analysis & Mitigation,” hosted by Ergo Expo. Below are our answers to the questions that were asked during the live event.
Q: When using NIOSH for palletizing, say 60 boxes, do you run the analysis 60 times and time-weight? Or do you run worst case scenario? What about for push/pull analysis (SNOOK), is it necessary to capture all the push/pulls within a work day?
A: In the interest of time, you may find that running the “worst-case” gives you a pretty good representation of the risk. It is very time intensive to run a Composite Lifting Index for 60 discrete scenarios, without a huge increase in accuracy. For the push/pull analysis, you are not measuring cumulative strain on the person – rather you are measuring each specific scenario separately. There is not a cumulative index for the Snook Tables.
Q: The U.S. is suffering from an obesity epidemic. Wellness professionals indicate it is a result of poor diets and lack of physical exertion. Both you and NIOSH indicate that injury statistics are being led by overexertion. Have you pondered this paradox?
A: Not formally, but it is an interesting question. It might also be that the number of jobs that are considered “heavy physical” has declined significantly in the last 30 years (primarily due to less manual labor in agriculture and farming). Because of this, perhaps the vast majority of the working population is not conditioned to perform physical work.
Q: What about lifting on inclined floor and stairs?
A: The NIOSH Lifting Equation doesn’t explicitly address this, but we feel that the accuracy of the equation would certainly be affected. A more comprehensive ergonomic evaluation may be needed to quantify the extent of other physical stressors, such as prolonged or frequent non-neutral back postures whilst on the stairs or ramp.
Q: Using the SNOOK tables, I find that once you input the data you get a percentage of the population that can perform the task safely. Can the level of risk be calculated more directly, like determining the lifting index for NIOSH lifting equation?
A: You can use the SNOOK tables to get a direct answer of how much force is acceptable. For the push/pull analysis, you will receive an output of what is the acceptable in the initial and sustained push force for the percent of the population you used in the input. For the carry analysis, the output will be the acceptable weight. We recommend using the same population as NIOSH (75% of women and 99% or men).
Q: I am a safety practitioner who preaches common ergonomic principles daily, yet I struggle to understand where wellness and ergonomics meet and work together.
A: While focused on different aspects of work life (wellness typically concerns overall physical and mental health and ergonomics focuses on improving workstation design and fitting the job to the employee) they both play an important role in employee health and safety. Improving the ergonomics of an employee’s workstation will not only reduce the risk of WMSDs but will also improve the employee’s morale and workplace attitude.
Q: How do you physically measure push/pull forces? A sudden, quick pull is different from one at 1ft/s. Please explain real-life speed and measurement.
A: When measuring push and pull forces you should duplicate exactly what the operator is doing. If the operator does a quick jerk you would do the quick jerk at the start to get the initial start force and then the smooth movement along the same path they use for the sustained force (up and over cracks/bumps and around corners).
Q: Given the huge snow fall this winter, how would you advise homeowners avoid the numerous back injuries that may have incurred from shoveling snow?
A: We would advise you to hire the neighborhood kid to do it! A fiver well spent, we say. Seriously, below are a couple of tips:
- Make sure the handle on your snow shovel is long enough, and shaped appropriately, to minimize the amount of back bending you do.
- Shovel the snow before it rains! Wet snow is heavier and is much more likely to exceed recommended guidelines.
- If the surface of your driveway or sidewalk is rough, avoid the shovels that have the metal ice scraper at the end. When pushing the shovel, those shovels are much more likely to “dig-in” to the ground, resulting in an abrupt trauma that may cause an acute back or shoulder injury.