Why write stuff about hydration policies? Why should I hydrate? With what should I hydrate? All relatively decent questions. Answers are likely to arise from the situation of the persons or people. I expect this entry to meander a little. Just be prepared for a smattering of ideas as you read further. Hopefully, the reader of this content can find some use in remaining safe and increasing the likelihood of an enjoyable summer.
People familiar with the heat and humidity of the summer in the southern US will tell you that the weather can sometimes be extreme and even oppressive. Mind over matter? If you don’t mind it don’t matter. Well. The Old Farmers Almanac of 2019 includes a guide to determine the heat index for individuals participating in outdoor activities. The Almanac defines the heat index as “a measure of how hot it feels when humidity is factored in with actual air temperature.” The heat index is often greater than the actual temperature outside and makes individuals even hotter than normal. For the purposes of this entry, a short discussion of the temperature versus the heat index and a comparison becomes more important for scheduling activities outside.
The Almanac depicts a chart in Fahrenheit and Celsius. This entry is discussed in terms of Fahrenheit. A discussion of temperature begins on a y axis at 80 degrees and increases to 100 degrees. The x axis depicts a scale of relative humidity starting at 40 percent and increasing by 5 percent to 100 percent. A temperature outside of 100 degrees F with 40 percent humidity feels like 109 degrees F. A temperature outside of 100 degrees F with 65 percent humidity feels like 136 degrees F. The increase of only 25 percent humidity outside increases the feels like temperature by a 27 degree margin.
Similarly, at the low end of the temperature range of 80 degrees F, increasing the humidity from 40 percent to 100 percent humidity only increases the feels like temperature outside by 7 degrees F. What percent increase in humidity yields the approximately same feels like temperature at 82 degrees F? The answer is 30-35 percent increase in humidity at 82 degrees F. At 84 degrees F? The answer here is a 15-20 percent increase in humidity at 84 degrees F. At 86 degrees F? 5 percent increase in humidity. This is according to the Almanac’s numbers. Two things are said about this change here. Decreasing the humidity outside while increasing the temperature results in a feels like temperature that is mostly bearable. Increasing the humidity and increasing the temperature could generate heat related injuries.
The above example showed that effects of the feels like temperature outside by a decrease to humidity while increasing the temperature. All of these temperatures with the accompanying humidity levels can be dangerous depending on the level of fitness, activity, age, and a number of additional variables. The last temperature on the Almanac’s scale that allows a reading of 100 percent humidity is 90 degrees F. Why is this particular temperature important? For starters, at 90 degrees F and 40 percent humidity, the feels like temperature already increases 1 degree F. The feels like temperatures below 90 degrees F are equivalent to or even less than the actual temperature in degrees F. At 90 degrees, the feels like temperature with the least amount of recorded humidity on the chart (40 percent) already feels hotter. At 90 degrees F with 50 percent humidity, the feels like temperature increases to 95 degrees. At 90 degrees F with 60 percent humidity, the feels like temperature increases to 100 degrees. At 90 degrees F with 70 percent humidity, the feels like temperature increases to 106 degrees. At 90 degrees F with 80 percent humidity, the feels like temperature increases to 113 degrees. At 90 degrees F with 90 percent humidity, the feels like temperature increases to 122 degrees. At 90 degrees F with 100 percent humidity, the feels like temperature increases to 132 degrees F.
The feels like temperature at 90 degrees F with 40 percent humidity and 100 percent humidity is a change of 31 degrees. Further increases in temperature above 90 degrees that coincide with increases in humidity condense the feels like temperature at a faster rate of increase.
The Almanac explains ways to self-regulate one’s internal body temperature. Drinking cool fluids, such as water, decrease the likelihood of heat related injuries. Caffeine, salts, alcohol, and strenuous exercise increase the likelihood of heat related injuries.
A fit person that exercises on a regular basis and hydrates with water and maintains a reasonable diet can ordinarily work through the heat related issues for a short period of time. The person would need to rest in a cool place and hydrate, but under reasonable circumstances, the person is likely to avoid heat related injuries.
I contend from this point forward that drinking one alcoholic beverage at least 18 hours prior to strenuous exercise in the extreme heat and humidity is likely to have adverse effects on the person. The extreme heat and humidity in this example is 90-92 degrees F with at least 90 percent humidity. The feels like temperature at 92 degrees and 90 percent humidity is 131 degrees F. The feels like temperature 92 degrees and 100 percent humidity is not recorded on the Almanac’s chart and is approximately 141 degrees F, based on estimates from the chart.
What is the point of this exercise? One beer 18 hours before strenuous exercise in the extreme heat and humidity is likely to produce a heat related injury of some type depending on the person’s age, fitness level, diet and general conditions. Strenuous exercise is cycling for one half hour or eight miles without replenishing the fluids lost from sweat.
This entry is not meant to dissuade people from having a good time during the summer. This is meant to help people plan activities around extreme weather accordingly.
Hydrate with cool water in the shade whenever possible. Do not become a casualty of the heat!