Radon. You can't see it. You can't taste it. You can't smell it. But, if you live in Maryland, it may be present in your home, and it may affect your health. Gold Key recommends that all homes be tested for radon.
The good news is that your home inspector from Gold Key can test radon levels, and a house with high radon levels (4.0 pCi/L or higher) can be fixed. Radon mitigation involves installing a system that either actively or passively vents the gas from beneath the foundation of the home.