Carbon Monoxide

odorless, colorless and tasteless but it can be deadly

From the CDC:  Carbon monoxide is often referred to as CO, which is its chemical symbol.  Unlike many gases, CO is odorless, colorless, tasteless, and nonirritating.  Red blood cells absorb CO over 200 times more readily than oxygen.  As levels of CO in the air rise, this gas replaces oxygen in the bloodstream.  As a result, body tissues are damaged and may die of a lack of oxygen.    

Knowing the major causes of carbon monoxide poisoning and using measures to eliminate them will prevent many needless tragedies.   The Centers for Disease Control (CDC) has a nice checklist with common questions and answers to help you to deal properly with the deadly hazard of carbon monoxide.   Here's the link:  http://www.cdc.gov/nceh/airpollution/carbonmonoxide/checklist.htm

The checklist will take you through common areas where CO can accumulate and provide advice.  Here are few excerpts: 

All gas appliances must have adequate ventilation so that CO will not accumulate

Rather than have vent pipes perfectly horizontal, in-room vent pipes should be on a slight incline as they go toward the exterior.  This will reduce the leaking of toxic gases in case the joints or pipes are improperly fitted.

When driving in heavy traffic, it is a good idea to keep your car windows slightly open.  Even with an air conditioner, CO can be drawn into a car while it is being driven slowly in heavy traffic.  Therefore, windows should be slightly opened.

When selecting gas equipment, look for items that carry the seal of a national testing agency, such as the American Gas Association or the Underwriters' Laboratory.