With the cooler weather, many people are using gas heaters to warm their homes.

They also may be using other gas appliances including gas hot water heaters and gas clothes dryers.

If one has appliances that use propane or natural gas in the home, it's important to have them inspected regularly to ensure they are working correctly.

Gas appliances that are improperly maintained can be a deadly source of carbon monoxide.

Improper venting of propane and natural gas space heaters is a major cause of carbon monoxide poisoning from vented gas space heaters.

If the heater is not vented properly, not vented at all, or if the vent is blocked, separated, rusted or corroded, dangerous levels of carbon monoxide can enter the home causing sickness and death.

Carbon monoxide also can be produced if the heater is not properly set up and adjusted for the type of gas used and the altitude at which it is installed.

Carbon monoxide poisoning kills more than 200 people and sends 5,000 more to hospital emergency rooms annually.

Many of these could be avoided if people had their gas appliances inspected regularly.

Carbon monoxide is extremely dangerous because it is invisible and odorless and its symptoms (headache, dizziness sleepiness, nausea, vomiting, or confusion) are similar to common illnesses such as the flu.

People frequently die from carbon monoxide poisoning while sleeping.