A Guide to Safe Field Operations
U.S. Geological Survey Open-File Report 95-777


In the Field


Normal comfort temperature range for man is between 60 and 90xfb F. Beyond these limits various precautions become necessary, depending on tolerance and adaptation to extremes. Most cases of hypothermia (condition of reduced body temperature that results in rapid mental and physical collapse) develop in air temperatures between 30 and 50xfb F. Hypothermia is aggravated by wet clothes, wind, hunger, and exhaustion. The best way to avoid hypothermia is to take more clothes than will be needed and to dress appropriately with layers of clothing and adequate headgear. Layers of clothing can be removed or added as the temperature changes. Prepare yourself for working in cold environments by:

The opposite physiological condition is hyperthermia, in which heat in excessive amounts can create a life threatening situation. Temperature, humidity, and physical exertion all contribute to this condition, but body hydration is the most important factor. Prepare yourself for working in hot environments by:

Sun exposure can cause first and second-degree burns, and you should be aware of your susceptibility to burning. It is recommended that you wear protective clothing and cover exposed skin with sunscreen. Remember that the intensity of radiation is greater at high elevations and exposure is increased where light is both direct and reflected from light surfaces, such as snow and sandy areas.

Thunderstorms are a serious danger while working in the field. Lightning is the storm's worst killer, but the intense rains, hailstorms, and wind associated with these storms can create dangerous conditions. Frequent monitoring of weather reports is important for scheduling your activities to avoid extreme weather conditions. While working in the field, keep an eye on the weather and notice whether towering cumulus clouds that mark the location of thunderstorms are approaching your work area. The safest place to be during a thunderstorm is in the field vehicle with doors and windows closed. General guidelines for avoiding dangerous conditions during thunderstorms are:

Additional information on thunderstorms and lightning can be found in National Weather Service NOAA/PA 83001 (June 1985).


Working in and around streams and rivers will subject you to many conditions in which the local terrain may cause slips and falls that could result in serious injury to you and your coworkers. You can't avoid all potential dangers, but you can minimize the risk of accidents by considering the following guidelines.


There are numerous animals that may represent a risk. Snakes and insects are probably the most common nuisances that you will face, but other reptiles and domestic and wild animals can cause serious injury, illnesses, and fatalities.

There are four snakes in the United States that are poisonous and should be avoided: rattlesnakes, cottonmouth, copperhead, and coral snakes. There are numerous species of rattlesnakes throughout the U.S. Cottonmouths and coral snakes generally range from the Carolinas through Florida, westward to Texas, and up the Mississippi Valley. Copperheads are found in much of the eastern U.S. and parts of Missouri, Arkansas, Oklahoma, and Texas. The most effective defense against snakes is to avoid being bitten. The following precautions should be taken to minimize the risk of snakes while working in the field:

Insects generally are a nuisance while working in the field, but they can be dangerous depending on the type of insect and your reaction to their sting or bite. Stinging insects, which include honey bees, killer bees, wasps, yellow jackets, hornets, and ants, are painful and can be dangerous to individuals that are allergic to the venom. The yellow jacket and hornet are the most dangerous because they are aggressive and can inflict multiple stings. You may be allergic to venom or you may develop an allergy with each new attack. Reactions can range from fever, light-headedness, hives, and painful swelling to a sudden drop in blood pressure and breathing difficulties. Biting insects, such as mosquitoes, chiggers, ticks, and various flies, are generally of less immediate hazard than stinging insects, but they may be carriers of disease. Ticks are the major carrier of disease in the U.S., transmitting Rocky Mountain spotted fever, Colorado tick fever, tularaemia, and relapsing fever or tick paralysis, and Deer ticks-Lyme disease.

Members of the spider family are another concern in both the field and office in certain parts of the country. Those of most concern are the black widow and brown recluse spiders and the scorpion. The spiders range widely in the temperate region and tend to seek dark hiding places. Scorpions range from the Gulf States to California and north into the dry areas of the west. Scorpions tend to seek shelter under bark, litter, sand, or rocks and may crawl into shoes, gloves, etc.

Keep in mind that there is just as much danger of falling off ladders and cableway platforms from trying to avoid bee stings as from the actual sting.

Common precautions against members of the spider family and insect bites and stings are:

Other animals may be a dangerous depending on whether you surprise them or represent a threat to their young, food, or territory. Most wild animals will be frightened away at sight, but the more domestic they are and the more familiar they are with humans, the less likely they will run from you. Because of this, dogs probably represent the greatest threat while in the field.

Significant animal threats also come from bears, moose, bulls some domestic livestock. These animals may actually chase people, so don't challenge them. Expect animals to defend their territory. Refer to the discussion of bear behavior by Brew and others (1978). Numerous smaller mammals are likely to be afraid of humans, but don't count on it. For instance, beware of porcupines and skunks that cease to flee and raise their tails vertically. They fight with their tails and the field person may become a target for flying quills or noxious excretions. The following guidelines are recommended to avoid animal attacks while in the field.

Poisonous Plants

The most common problem with poisonous plants is the allergic reaction that individuals have to the sap of poison ivy, poison oak, and poison sumac. The sticky sap of each plant can cause an allergic skin reaction of varying intensity depending on the amount of contact and the degree of susceptibility of the individual. The sap can be transferred directly by brushing against or handling the plants and indirectly from tools or clothing and from smoke of burning plants.

Avoid allergic reactions to poisonous plants by:

Some plants are poisonous to eat, and it is advisable not to eat any wild plants unless you have knowledge of safe plants and plant parts.

A Guide to Safe Field Operations
U.S. Geological Survey Open-File Report 95-777

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Last Modified: 09:56 27June1996 ghc