The average indoor radon level is about how many picocuries per liter?

The average indoor radon level is about how many picocuries per liter?

• A. 0.5
• B. 2.0
• C. 3.0
• D. 1.3

Answer: (D)

Radon is a naturally occurring radioactive gas that can build up in homes, so understanding indoor levels means knowing the typical concentration people tolerate in daily life. The national average indoor radon level is about 1.3 picocuries per liter, a figure widely cited by health authorities as the representative indoor concentration. Outdoor levels are much lower, while higher indoor values indicate unusually concentrated radon and may prompt mitigation. Because 1.3 pCi/L aligns with this standard average, it’s the best match for what most homes measure on average. The other numbers are not the commonly cited average, though they may occur in some situations; they simply don’t reflect the typical indoor exposure. For context, 4 pCi/L is the EPA action level, but this question targets the average rather than the remediation threshold.

Radon is a naturally occurring radioactive gas that can build up in homes, so understanding indoor levels means knowing the typical concentration people tolerate in daily life. The national average indoor radon level is about 1.3 picocuries per liter, a figure widely cited by health authorities as the representative indoor concentration. Outdoor levels are much lower, while higher indoor values indicate unusually concentrated radon and may prompt mitigation. Because 1.3 pCi/L aligns with this standard average, it’s the best match for what most homes measure on average. The other numbers are not the commonly cited average, though they may occur in some situations; they simply don’t reflect the typical indoor exposure. For context, 4 pCi/L is the EPA action level, but this question targets the average rather than the remediation threshold.