Your Body Almanac

South Dakota

Radon in the east, West Nile in summer, and hard Plains winters.

The eastern half of South Dakota sits in EPA's highest radon zone, and the state has some of the highest West Nile virus rates in the country. Winters are long, windy and cold, with little sun for making vitamin D.

01

High radon in many homes

Radon is an invisible, odorless radioactive gas that seeps up from soil into homes, and it is the leading cause of lung cancer in people who don't smoke. EPA's map puts most counties in the eastern half of South Dakota in Zone 1, its highest-risk category, and the rest in Zone 2. Testing is the only way to know your home's level.

SourcesSouth Dakota — EPA Map of Radon Zones (EPA)Radon (South Dakota Department of Agriculture and Natural Resources)Health risk of radon (EPA)
Test your home for radonAs neededRadon is invisible and odorless, so a simple test is the only way to know your level. Fix it at 4 pCi/L or higher.
02

West Nile virus from mosquito bites

From 2009 to 2018, South Dakota had the second-highest average rate of serious, brain-affecting West Nile illness in the US. Most cases start between July and September. Older adults face the highest risk of severe disease.

SourcesSurveillance for West Nile Virus Disease — United States, 2009–2018 (CDC MMWR)
Use insect repellentAs neededUse an EPA-registered repellent on exposed skin when mosquitoes or ticks are around.
03

Extreme cold and wind chill

Plains winds push wind chills far below the air temperature, and exposed skin can freeze quickly on the coldest days. Hypothermia can creep up during long outdoor work or a breakdown on a rural road.

SourcesWind Chill Chart (National Weather Service)Winter Weather (CDC)
Dress in layers for the coldAs neededWear several loose layers, a hat, gloves and waterproof insulated boots, and carry spares.
04

Little winter sun for vitamin D

Your skin makes vitamin D from the sun's UVB rays. A classic study found that winter sunlight in Boston, at 42 degrees north, made no vitamin D in skin from November through February. South Dakota lies north of that, so through the winter food is the more reliable source.

SourcesVitamin D — Health Professional Fact Sheet (NIH ODS)Influence of season and latitude on the cutaneous synthesis of vitamin D3 (Webb et al., 1988, PubMed)
Get vitamin D from foodDailyEat fatty fish, fortified milk and UV-exposed mushrooms so you are not relying on the sun alone. Ask your doctor about vitamin DYearlyIf you get little sun or few vitamin D foods, ask at your checkup whether testing or a supplement makes sense for you.

When to see a professional

Get care for numb, hard or waxy-looking skin after cold exposure, or for sudden severe headache, stiff neck, confusion or weakness in summer. Tell your doctor about long-term radon exposure, especially if you smoke or used to.