Temperature can be taken in many ways, and the words to help describe temperature are used in many situations. One of the most common, other than looking at a thermometer, is in fashion and magazines where the human body is put on display. Two of the most common words when it comes to human bodies and/or fashion are “hot ” and “cool.”
That body looks hot. That is a pretty cool ensemble. And either way, the person could, in a sense, feel “hot” or “cool” based on their looks.
But when it comes to worker safety, feeling hot or cool is not a surface or exterior issue regarding body shape or clothes. Actually feeling hot or cool can make or break a person’s ability to effectively work in extreme heat or cold when on a job site. As safety officers, it is our job to monitor these workers who spend time in the elements and make sure that they are not succumbing, and are in fact getting acclimated, to any extreme temperatures that are outside of a comfortable range.
[Image courtesy of Flickr user Bark via a Creative Commons license]Temperature is certainly one factor in determining whether workers should be outside, and for how long. But safety officers also have to keep in mind several other things that help determine a person “feeling” hot or cold, regardless of what a thermometer says.
Heat is Not About the Sun
Any of us can “feel” hot even on a day that would not be considered hot by many standards. But there are also those who do not “feel” hot even when it’s hot enough to fry an egg on the sidewalk. (And yes, there is a temperature hot enough to do it. A TV station in Phoenix, Ariz., showed an egg frying on the sidewalk when the temperature hit 122 degrees Fahrenheit in June, 1990.)
So what goes into different people feeling “hot” at different temperatures? Why can one person wear shorts when it is 60 degrees Fahrenheit while another is in a sweater and threatening to don a parka over it? Well, there can be a lot of factors that go into determining how a person “feels” in certain weather conditions, which is why when I wrote about aclimation, it was important to ease your workers into the heat while also monitoring them while they were outside.
And heat does not necessarily come just on a sunny day. There are plenty of cloudy days where heat plays a role and people can still “feel” hot.
Factors that Affect Feeling
Of course, feeling hot and being hot can be two different things; however, for the sake of safety for your workers, we would always advise you to err on the side of a worker who “feels” hot, because if a person feels outside of normal comfort, that could be distracting to the worker, and even if he or she is not dehydrated or succumbing to the heat, the distraction could affect safety and the worker may make a mistake and put himserlf or herself at risk for an incident.
With that in mind, you may have to be a meteorologist as well as a safety professional, because you will need to pay attention to these factors, to make sure your workers remain comfortable and do not “feel” hot while they are working. Here are several things to look for to determine a worker’s ability to work outside in the heat:
* Temperature. This is the most obvious, but you have to be careful where you have your themometer placed. However, certainly excessive air temperature affects how hot someone “feels.”
* Radiant heat. This is sunlight or any other external heat source that gives off heat, which can affect a thermometer’s reading. Asphalt, hot water, open flame – these are examples of radiant heat that might make a person feel “hotter” than what the air temperature might be. If a worker is working otuside on asphalt, always be more cautious with them because of the radiant heat, as compared to those who work on dirt or gravel or grass.
* The concept called relative humidity – which is not the actual humidity level, but it is the level of humidity in the air relative to normal. All air holds some water vapor, but the higher the temperature of the air, the more water vapor it can hold. At high temperatures, higher humidity means sweat does not evaporate as quickly, and thus the body “feels” hot more readily and quickly. At high temperatures you need low humidity to “feel” less hot. A lower level of heat with high humidity may be more dangerous than egg-frying dry heat.
* Moving air. In a hot environment, when the air does not move, you can actually feel hotter – like you are standing in an oven. If there is a breeze, it can cool off a person, provided the wind is cooler than the person.
* Of course, moving around in the heat is a factor. Physical movements generat heat, so if you do a lot of work in a hot environment, your heat stress level will increase wel beyond what the temperature and/or humidity might suggest. Do not overwork on a hot day without taking proper precautions.
* Clothes. On a hot day, thinner and lighter clothing goes a long way toward keeping people from feeling hot. However, if your workers are required to wear heavier safety equipment or jackets (like firefighters), you will need to take even more precautions because those workers will not be able to cool off properly and thus may feel hot much sooner than temperature or humidity may indicate.
*Physicality. The truth is that overall physical health, weight and age do factor into a person’s ability to handle extreme temperatures. Again, everyone is different, so this is not to say that everyone over 50 years old or above a certain body mass index number (BMI) should not work in the heat or cold; but it is up to you to know and understand your workers and their capabilities and keep them safe yet productive.
*Drugs. This goes for alcohol use and prescription drugs use, not just illegal drugs. Most drugs will affect a person’s susceptibility to either heat or cold; some (like alcohol, marijuana and antidepressant drugs) will make a body weaker against both extremes, while others affect either heat or cold. It is important for you, as a safety officer, to know as much about this as possible about your workers; not necessarily from a liability or insurance standpoint, but for you to know from a safety standpoint so that you do not put people at risk if they are impacted by any drug use whatsoever. Even painkillers, by the way.
For your information, a more efficient way to check potential heat stress risk is by looking at Humidex (Canada) and Heat Index (U.S.), which are formulas that combine air temperature with relative humidity to come up with a “feels like” value. There are values for Humidex and Heat Index where it would be suggested that people do not go outside at all, or have minimal exertion or exposure while outside. If your weather forecasts provide this “feels like” value, pay heed to it; if the value is signficantly higher than the air temperature, you might want to think carefully about whether your workers should be outside and for how long.
For the next post, I will get into heat stress – what it is, how to tell if a worker has a heavy dose of it and what you should do. (Hint: Not a good idea to tell the worker to “suck it up.”)