Which hazard can generally be greatly reduced through proper ventilation?

The correct answer is radon, as proper ventilation can significantly diminish its concentration in indoor spaces. Radon is a naturally occurring, radioactive gas that can seep into homes from the soil or rock beneath them, accumulating in enclosed areas. One of the effective mitigation strategies for radon involves increasing ventilation to facilitate the exchange of indoor air with outdoor air. By allowing fresh air to circulate, you can lower the levels of radon, thereby reducing the potential health risks associated with long-term exposure.

In contrast, other hazards such as carbon monoxide, asbestos, and lead do not have the same benefits from ventilation. Carbon monoxide, produced primarily from combustion engines or heating devices, requires proper detection and elimination of sources rather than just ventilation. Asbestos is a fibrous material that poses health risks when disturbed and released into the air, so it is often best managed through proper removal rather than just increasing airflow. Lead contamination typically comes from paint, plumbing, or soil, and similar to asbestos, controlling lead hazards demands remediation efforts rather than relying solely on ventilation.