You might have lived with dangerous conditions in your home for years. And maybe its never been an issue. It’s also possible that it has been but you didn’t realize it. For example, poor air quality in the home is a major cause of asthma. Similarly, frequent headaches can be from elevated Carbon Monoxide in your home.
So if you plan to make your home more energy efficient, especially if you make it more air-tight, then you want to make sure you aren’t going to make worse an already dangerous situation.
Carbon Monoxide is called the silent, deadly killer because it is invisible and odorless. If you have any natural gas, propane, kerosene or oil-fired heating units, make sure they are running well. Unvented space heaters are NEVER safe to have in your home. You should probably not do any air sealing if you intend to keep unvented space heaters in your home.
Other major safety hazards in the home you should consider are mold and electrical hazards such as exposed wires or live knob-and-tube wiring.