If you have a carbon monoxide detector it should be checked on a regular basis; if it is a battery type go ahead and change out the batteries. Now is also the time to have your heaters checked and filters changed.  A dirty filter not only creates more dust in the home but can cause furnaces to overheat and trip.  If you haven't had your system checked in a while give Mullin Services, Inc. a call at 918-286-1200.