Twisting the knee is a common cause of overstretched or torn ligaments of the knee. The knee may give out suddenly when the ACL is torn and there may be a popping sound upon injury. Symptoms of a torn ACL include knee pain, swelling, stiffness, and bruising.
Early symptoms of carbon monoxide poisoning such as headaches, nausea, and fatigue, are often mistaken for the flu because the deadly gas goes undetected in a home. Prolonged exposure can lead to brain damage and even death.
Normal Levels of Carbon Monoxide in a Home. In the U.S., about 170 people die each year from prolonged exposure to carbon monoxide in the home. The levels of carbon monoxide, or CO, in your home will vary if a gas stove is present and properly adjusted, according to the Environmental Protection Agency (EPA). If you own a gas stove, the average CO level in your home will range from 5 to 15 parts per million (ppm). If your gas stove is poorly adjusted, the average CO reading is closer to 30 ppm or higher, which can cause dangerous reactions if the problem remains unresolved.