Picked First: Why Radon Belongs to the Dangerous Team
How a Group 1 carcinogen threatens children — and what we can do about it
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Imagine you’re on the playground, and everyone is lining up to pick teams for a game. The kids who are picked first are usually the strongest players — the ones everyone knows will make a big impact in the game.
Now, let’s take that same idea into science.
The Science Game
Scientists also “pick teams,” but instead of players, they’re sorting things that might cause cancer.
Group 1 is like being picked first. These are the substances that scientists are absolutely sure cause cancer in people. They’ve seen it happen many times, and there’s no doubt left.
Radon got picked first for this team. Just like the strongest kid at recess, radon is a “strong player” in the cancer game — but in a dangerous way.
From the Editor
Why It Matters for Kids
So when we say children are in a “Group 1 radon situation,” it means radon is on the most dangerous team — the one we know for sure can hurt people. And because kids are still growing, breathing faster, and spending time in schools and basements where radon can build up, they can get affected more.
When Children Are in a Group 1 Radon Situation
When we talk about children being in a “Group 1 radon situation,” we’re referring to something very serious. Radon gas has been classified by the World Health Organization’s International Agency for Research on Cancer (IARC) as a Group 1 carcinogen—a category reserved for substances with clear and sufficient evidence of causing cancer in humans. That means radon is in the same category as tobacco smoke and asbestos.
For children, the stakes are even higher. Here’s why.
Why Children Are More Vulnerable
Developing bodies and faster breathing. Children’s lungs and tissues are still growing, making them more sensitive to damage from carcinogens. They also breathe more quickly than adults, which means they can take in more radon relative to their body weight.
Indoor time. Children often spend much of their time indoors—whether at home, in classrooms, or in afterschool care. Unfortunately, those same indoor environments can trap radon, particularly in basements and ground-floor rooms.
The Long-Term Risk
Radon exposure doesn’t cause immediate symptoms. Instead, its effects accumulate silently, increasing the chance of lung cancer years or even decades later. When exposure starts in childhood, the risk is especially concerning: children have more years ahead of them for the damage to show up as cancer in adulthood.
Where Radon Lurks
Schools, childcare centers, and homes with basements are common hotspots for radon buildup. Because radon is colorless, odorless, and tasteless, children can be exposed for years without anyone knowing—unless the building is tested.
The Numbers Behind the Risk
So what happens if a child spends 12 years in a school with elevated radon levels?
There’s no simple equation that predicts exactly who will develop lung cancer, but science does give us clear indicators:
• EPA estimates show that a lifetime exposure (70 years) to radon at the action level of 4 pCi/L could cause 7 out of 1,000 nonsmokers and 62 out of 1,000 smokers to develop lung cancer.
• At 20 pCi/L, the risk jumps to 36 per 1,000 nonsmokers and 260 per 1,000 smokers.
• While 12 years is not a lifetime, it’s still a significant cumulative dose. And because children breathe faster and have longer lives ahead, their relative risk is considered higher than adults exposed for the same span.
Putting It Into Perspective
• If radon levels in a school hovered around 4 pCi/L, children exposed for 12 years would carry a measurably higher lifetime cancer risk than their peers in radon-safe schools.
• If levels were 10–20+ pCi/L, the added lifetime risk could be several times higher.
• For lifelong nonsmokers, the danger is lower but still real. For children who later smoke, radon exposure multiplies their odds of lung cancer dramatically.
The Bottom Line
We cannot tell a parent or teacher the exact percentage chance that any single child will develop lung cancer from 12 years of school radon exposure. But we can say this with certainty: those years matter. Daily exposure to a proven human carcinogen during a critical stage of growth substantially increases long-term risk.
The solution is simple and powerful: test schools and homes for radon, and fix any building above the action level of 4 pCi/L. By reducing exposure early, we can prevent future cases of lung cancer before they ever begin.
In short: A Group 1 radon situation means children are being exposed to a known carcinogen at the very time their bodies are most vulnerable. Testing and mitigation are not optional—they are urgent acts of prevention.
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