One of the lesser known tasks for the ATC is measuring relative humidity (RH), and ensuring that athletes are participating in a safe environment. The main concern is that when the humidity is high, the body lacks the environment for evaporation to occur. Just because an athlete is sweating doesn't necessarily mean they are cooling properly. A common question I hear from our students is "Can't we just check online?" It's another useful reminder to educate them that utilizing online weather predictions is not only the easy way out, but it could also be highly inaccurate.
Case in point: If I go to an online weather service and type the town/city of an event I'm covering, the relative humidity reading is only as accurate as the exact location the measurement was taken. On our campus alone, we may have several sporting events occurring simultaneously on a turf field, indoors, a grass field, or a track. Why does this matter? In a word, Temperature. The higher the temp, the more likely adverse participation conditions exist. For instance, if it is 70 degrees and raining, you would obtain a RH reading of 100%, but you wouldn't really be worrying too much about heat related illness. However, if it is 90 degrees and not raining, but you obtain a high RH reading, the situation is a little more urgent. Now, I could dive into synthetic fields but it's a topic for another blog. I will attempt to be succinct. As you can read here, synthetic fields are notoriously higher in ambient temperature than surrounding fields. Depending on weather conditions, guidelines may have to be altered for practices/games on the turf field but not surrounding fields. Now before it sounds as if I am unfairly biased against turf fields (which I am not), it is a fact that they "heat up" more so than their natural counterparts, as stated here by a well known manufacturer. More on that later though.
So how does it work? I love sling psychrometers. They are small, easy to use, and allow me to feel more comfortable if I have to make a decision regarding safe competition.
Personally, I prefer the manual, as relying on electronics isn't always the best option for me. It is small, fits in the kit, isn't affected if rain gets it wet from time to time and simple to use. They should be in every ATC's kit, regardless of what region of the country they work in.
1. Wet the wick on the Wet Bulb thermometer.
2. Depending on the model, walk to the center of the field you are participating on, and "sling" the psychrometer for 1-3 minutes.
3. Working like a slide rule, take your dry bulb reading and wet bulb reading and align them. A small arrow on the device points to the RH reading.Check out the clip below from Southern Mississippi, which does a nice job of explaining how and why we use these tools.
So what can an ATC do to prevent athletes succumbing to heat related illnesses?
1. Go to the NATA website here, and familiarize yourself with consensus statement on Heat Acclimatization
Then go to the CSMF website here for more info. (a fantastic resource in my humble opinion).
2. Take regular, on-site RH readings, utilizing a hand held manual or digital sling psychrometer.
3. Water down the field. Manufacturers recommend watering synthetic fields down for 10 minutes, which will then lower the temperature (and of course effect RH readings).
4. Understand acclimatization. Just because you don't work or live in a "hot" climate, doesn't mean you shouldn't have a psychrometer to work with. In fact, you may be the one who needs it most? Take Maine for instance, we are not acclimatized to hot, humid weather, which means we are more likely to succumb to it.
This will allow you to make accurate decisions on the field, and help protect the safety of your athletes.