Which gas can be accumulated in poorly ventilated buildings?

Which gas can be accumulated in poorly ventilated buildings?

ناقص ہوادار عمارتوں میں کون سی گیس جمع ہو سکتی ہے؟
Explanation

Radon is a gas that can be accumulated in poorly ventilated buildings.

Radon is released from Radium.
It originates from the natural decay of uranium in soil, rock, and water
It can enter buildings through cracks and other openings in the foundation.
Prolonged exposure to high levels of radon gas can increase the risk of lung cancer