These are the quick and easy ways to keep your home safe. They're also quite reasonable.
1. We recommend a low level Carbon Monoxide (CO) detector as standard CO detectors sensitivity is far too low to keep you safe. Home evacuation is set at 1oppm. Standard co detectors cannot alarm below 70ppm. We sell these for $160 or they're available for $200 plus tax from www.trutechtools.com/Defender-LL6170-Low-Level-Carbon-Monoxide-Monitor-Alarm
2. Air quality monitors provide real time as well as long term exposure levels to Radon (21k deaths per year), co2 (carbon dioxide - builds up naturally in our environment and impairs productivity and sleep), Volatile organic compounds (VOC - chemicals), particulate matter (PM), Humidity (which affects air quality and comfort), temperature, and barometric pressure. Most of these effect the comfort and health of everyone in our homes so this tool will help to understand if we're safe and healthy or need help. $300 from https://discount.airthings.com/discount/view-plus.html minus 10% with promo code: portmech-10OFF
More info about how these affect your health and comfort here: https://www.airthings.com/contaminants
3. Furnace preventative maintenance. The first and most important thing we do is ensure the heat exchanger, the part responsible for keeping the dangerous gases out of our home, is safe. This is done with a combustion analysis - this is what the picture above is showing. Once the furnace is verified to be safe, we move to ensuring the furnace is as reliable, efficient, and quiet as possible. $105