Is Snow Safe to Eat? What to Know
Chris Tobin / Getty Image
Medically reviewed by Jonathan B. Jassey, DO
Eating snow can feel like the ultimate winter treat. It's cold, it's crunchy, and can easily be made into a snow cone. For other people, eating snow is just plain gross. So it actually safe to eat snow? The short answer is: it depends.
Some type of snow is cleaner and, therefore, safer to eat than others. Still, even clear-appearing snow can contain environmental contaminants that aren't good for your health.
Here's what to know about what might lurk in your icy snack, and the safest way to eat snow, if you want a bite anyway.
What Could Make Snow Unsafe to Eat?
Snow can become contaminated with pollution, chemicals, algae, and bacteria from the ground and air. When snow falls from the clouds, its intricate, criss-crossed ice crystal structure basically locks in pollutants. As a result, snow may contain air pollutants like car emissions and black carbon from wood-burning stoves and coal-fired plants. Cold weather even increases harmful air pollution from vehicles idling more and producing more emissions from cold starts.
Snow can also pick up harmful chemicals from the environment. Plowing the driveway or the road pushes dirt and road-salting chemicals like magnesium chloride into the snow. Studies have also found pesticides and microplastics in snow samples that usually enter water, soil, and the atmosphere.
Most microbes (bacteria and viruses) don't survive cold temperatures. But snow can still become contaminated with dirt, sewage, and animal waste that contains illness-causing E. Coli bacteria. A type of algae called Chlamydomonas nivalis also thrives in snow, causing patches of pink snow called watermelon snow. This algae isn't directly harmful to humans if ingested. Still, it often appears in melting snow, which is more likely to have other dirt and toxins.
Where Is Snow Safest to Eat?
It's safest to eat the top, fluffy layer of white snow. This is the freshest and potentially cleanest layer of snow. Avoid eating deep layers of snow that look dirty or snow that has been plowed into a pile. This snow will contain more pollution and contaminants. You also want to avoid eating discolored yellow, brown, orange, blue, or pink snow.
When choosing where to collect snow, only eat snow in areas you know your pets haven't pooped. It's also best to avoid eating snow from areas near water runoff, sewage, or road salt sources. A safer place to eat snow may be between your home and the road. However, the area where snow might be the "cleanest" will truly depend on your specific setting.
When Is Snow Safest to Eat?
It may be tempting to snack on fresh snow, but it's safer to start eating snow a few hours into it falling. Fresh falling snow is dirtier than snow that falls a few hours into a storm. This is because when snow traps all that nasty pollution as it falls, it actually cleans the air. Think of snow like a squeegee scrubbing pollutants from the atmosphere. As the air is scrubbed clean, snow also becomes cleaner.
Letting snow pile up for a few hours also helps move snow farther away from the ground, which may contain additional chemicals, pollutants, and bacteria. However, it's best to avoid eating snow that has sat too long and is starting to melt. Melting snow is more likely to contain pollutants and other contaminants from the soil and water runoff.
Potential Side Effects of Eating Snow
People don't typically get sick after eating snow. However, eating contaminated snow could lead to illness, infections, and accidental poisoning. Eating snow contaminated with E. coli bacteria could make you sick, leading to side effects like severe stomach cramps, fever, vomiting, and diarrhea. Mild infections usually get better in about a week.
The effects of ingesting snow contaminated with pollutants, pesticides, and microplastics aren't well understood. Research shows outdoor air pollution increases health risks like heart disease, cancer, and respiratory infections. These health risks are linked to inhaling pollutants, not eating them. Still, eating snow contaminated with high concentrations of toxins or chemicals could lead to poisoning. Poisoning could be mild or severe, causing symptoms like:
Changes in pupil dilation
Drooling or dry mouth
Heartbeat or breathing that becomes rapid or abnormally slow
Stomach pain
Nausea and vomiting
Confusion
Burns or swelling of the mouth and lips
Loss of vision
Eating snow can also be dangerous if you're stranded in cold weather and need water. Eating snow can lower your body temperature, increasing your risk of hypothermia. This is because it takes your body a lot of energy to melt snow. This excess energy expenditure can also dehydrate you. If you are in extreme weather conditions and need water, melt the snow first. Ideally, boiling water will make it even safer by helping to kill some germs that may linger in snow.
What to Do If You Eat Contaminated Snow
If you just ate snow and are starting to feel sick, don't panic. Treat yourself like you have a gastrointestinal illness if you have symptoms like upset stomach, vomiting, or diarrhea. Make sure you stay hydrated by drinking fluids (with and without electrolytes) and give your body time to rest. Contact your healthcare provider if your symptoms don't improve after three days, you can't keep liquids down, or you have diarrhea and a fever higher than 102˚F.
If you think you accidentally poisoned yourself by eating snow, call the Poison Control Center emergency number at 1-800-222-1222. They can walk you through the next steps depending on your size, symptoms, when you ate snow, and if you've vomited. You want to avoid taking activated charcoal or ipecac syrup to throw up. If someone has passed out or stopped breathing after eating snow, call 911 immediately.
How to Eat Snow Safely
The safest way to eat snow is to make sure you're eating the cleanest snow possible. If you can't resist eating snow, here are some tips to make snacking on snow safer:
Wait for snow to fall for a few hours before eating
Eat only the top layer of white snow
Avoid eating snow that appears melted or dirty
Avoid eating snow that is orange, blue, or pink
Avoid eating plowed snow
Avoid eating snow off of roads, sidewalks, and vehicles
Avoid eating snow in areas where pets use the bathroom
Avoid eating snow near sewer or septic systems
A Quick Review
Eating snow isn't inherently unsafe, but it can put you at risk of ingesting harmful pollutants and bacteria. As snow falls, it picks up pollution, microplastics, and pesticides. It can also become contaminated with dirt, feces, and chemicals. That said, snow becomes cleaner the longer it falls. The first snowfall collects more contaminants and helps clean the air for future snowfall. If you want to eat snow, eating the top white layer a few hours into a snowstorm is safest.
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