As cooler weather comes, space heater use increases. Power outages greatly increase space heater use. As with all energy sources, there are some risks involved. Space heaters come in fixed-location and portable types. Also, some are for outdoor use only and some are for indoor use only. Read the container and instructions carefully to determine if the heater is appropriate for the use you intend.
It seems that each year there are deaths from carbon monoxide poisoning from propane and kerosene space heater use. All combustion generates some carbon monoxide. If you use a propane heater indoors in a very tight location (little ventilation), you risk being in a place with built-up carbon monoxide. Heaters specified for outdoor use will cause a more rapid build-up of carbon monoxide than one rated for indoor use.
Carbon monoxide is an invisible, scentless, tasteless gas that kills in high enough concentrations. Using a carbon monoxide detector will warn you if concentrations get too high. Other symptoms of carbon monoxide poisoning are nausea and headache, but these should not be depended on in place of a detector.
Space heaters can also cause suffocation. They use the same oxygen out of the air that you need to support your life. Any heater used indoors should be equipped with an oxygen depletion sensor (ODS). The unit will shut down before it uses too much of the oxygen if it has an ODS. However, be warned that it will generate a higher concentration of carbon monoxide as it decreases the oxygen level in the room.
If you take nothing else away from this section, please remember the part about not using outdoor heaters indoors.