| Missouri Environment and Garden | Volume 8, No. 7 |
| News for Missouri’s Gardens, Yards and Resources | July 2002 |
Exposure to extreme heat can make you seriously ill. Factors that
affect the probability of becoming ill include your physical activity,
age, and state of health. Also to be considered are the clothing you
wear and the humidity level. If left unchecked, a heat-related
illness can become serious in a relatively short period.
To better understand how to minimize heat stress or heat-related illnesses, the gardener must understand what causes heat stress and when it is most likely to occur. Heat stress occurs when the body is unable to get rid of excess body heat by its normal exhaust methods - either from sweat evaporation, or from increased blood circulation to the skin surface where body heat can escape through radiation.
If gardening keeps you outside for long periods, it is especially important that you recognize the signs of a heat-related illness.
The four major environmental conditions that affect heat stress are air temperature, humidity, wind velocity, and radiant heat. Combine these with individual factors such as age, gender, weight, physical and medical conditions, and a person’s degree of heat acclimation, and you can begin to predict how well a person might hold up in a hot, humid, still environment.
The majority of heat-related problems such as early heat illness or fainting, heat cramps, heat rash, and heat exhaustion are considered minor. Just because these illnesses are considered minor doesn’t mean that they aren’t important to recognize and to try to avoid or minimize. For ill or frail individuals, these illnesses may require medical attention.
One heat-related illness considered serious is heat stroke. Someone suffering from heat stroke can be in a life-or-death situation, and the first response should always be to call 911 for medical assistance.
The following are just some of the signs, symptoms, causes, and treatments of these illnesses; consult medical references for additional information:
Signs and symptoms - dizziness, fatigue and irritability; difficulty concentrating or making decisions
Cause - reduced blood flow to brain
Treatments - drink water; loosen clothes; rest in shade
Signs and symptoms - painful arm, leg or stomach muscle spasms; thirst and heavy sweating; (may not occur until after gardening activities)
Cause - body salt loss due to sweating
Treatments - drink water, and avoid drinks with alcohol or caffeine; remove hat and loosen clothes; rest; lightly stretch muscles in a cool location
Signs and symptoms - pricking sensation and tiny, blister-like red skin spots, usually on body areas covered by clothes
Cause - plugged and inflamed sweat glands
Treatments - wear loose clothes; wash skin; apply talcum powder
Signs and symptoms - early heat illness signs plus loss of coordination; collapse; heavy sweating; cool, moist, pale skin; dry mouth with excessive thirst; fast pulse; low to normal temperature
Causes - reduced blood circulation and flow to brain; dehydration
Treatments - if conscious, give cool water to drink (do NOT give beverages containing caffeine or alcohol). The individual should drink slowly by giving a half glass of cool water every 15 minutes; rest lying down in a cooler, shaded area; loosen or remove clothing and hat; splash cold water on body and massage arms and legs.
According to the American Red Cross, heat stroke may occur suddenly and is life threatening; they recommend the following:
Signs and symptoms - dizziness, confusion, headaches, irrational behavior, coma; reduced or no sweating; fast pulse; rapid breathing; convulsions, nausea, vomiting
Causes - dehydration; sustained exertion; reduced blood flow to brain, heart, etc.; body unable to cool itself; overexposure to high temperatures even with out exertion
Treatments - immediately call 911; move to shaded area; remove shoes
and outer clothing, wrap in wet cloth/pour water on/fan rapidly;
elevate legs; clear vomit to prevent choking; if victim refuses water,
is vomiting, or there are changes in level of consciousness, do not
give anything to eat or drink.
How should gardeners avoid becoming a safety threat to themselves and others when it’s hot? Start by evaluating the potential risk of heat stress relative to the individual factors listed above. Someone who is older, overweight, in poor physical condition, taking allergy medication, or not used to being out in the heat is at far greater risk than someone who is young, trim, on a regular exercise program, and used to the heat.
Become a weather watcher. Set up a small weather station (with a high/low thermometer, rain gauge, etc.) to monitor not only the temperature, rainfall, etc., relative to plant growth, but also relative to personal safety. Watch or listen to the weather forecast each morning and noon to know in advance when stressful environmental conditions may occur. Plan activities for a cooler time of day or season.
Evaluate garden tasks and the time of day during which they must or can be done. Tasks that occur outdoors in sunny areas should be done in early morning or late afternoon and not during the midday heat. Most watering, pruning, dead heading, etc., is better for plants when done in early morning. Many chemicals, especially insecticides, are better applied late in the day when the wind is down and beneficial insects are not present. Also, many chemicals volatilize quickly in the heat, losing their effectiveness and possibly causing harmful reactions to the applicator.
Allow yourself to acclimate to the heat slowly. Over a period of a week or two, gradually increase the amount of time spent in hot, still areas or in direct sun. Don’t save hours of hoeing weeds from garden beds for the first day it goes over 90°F. Avoid working on surfaces such as asphalt or near items such as metal that may become very hot.
Be sure to stay hydrated, drinking as much liquid as possible. Don’t wait until you are thirsty to have a drink, as thirst is an indicator that your body is already dehydrated. Water is preferred, except when heat cramps occur (then drink a lightly salted beverage like a sports drink). The water’s temperature should be cool, not cold. As long as their sugar and salt content is low, flavored beverages such as fruit juices, iced tea, and lemonade are good water substitutes if they encourage large quantity consumption.
Perhaps one of the easiest ways to reduce heat stress is to dress appropriately. Though tempting, do not work in the yard in a tank top or without a shirt due to the potential for sunburn and skin cancer. Wear loose fitting, light colored clothes. Keep the fabric content high in cotton to aid sweat evaporation. Neckbands, headbands, wristbands, visors, and hats can increase evaporation to keep the body cool.
Lastly, take frequent breaks to reduce the amount of time spent in the sun or heat. After working for an hour, take a break to cool down and have a drink in the shade to reduce the build-up of heat stress on your body.
Karen Funkenbusch, Research Associate, Missouri AgrAbility Project and Rural Health and Safety Program, (573) 882-2731