House fires can happen to anyone, and approximately 5,000 Americans die each year as a result. Some of the common causes are:
Electrical: caused by unsafe conditions such as overloaded circuits, damaged wiring and the misuse of extension cords.
Wall Outlets: a loose-fitting wall outlet may cause overheating, which can eventually lead to a fire.
Light Bulbs: light bulbs that exceed the rating capacity of the fixture could overheat and cause a fire.
Candles: these should only be burned on a sturdy, heat-resistant surface or in receptacles specifically made for candles. You should never go to sleep while a candle is still burning.
Kitchen Fires: distractions are the leading cause of kitchen fires, and oil, fat and grease are the leading contributing factors.

Common causes of forest fires include lightning, human carelessness and arson. Paradoxically, the prevention of small natural forest fires is a major contributor to extreme forest fires. Fires tend to be more common and severe during years of drought and occur on days when there are strong winds. Plants have evolved to stay alive after a fire by various strategies, or even encourage it as a way to get rid of competition from less tolerant species, and today it is acknowledged that forest fires are a natural part of the ecosystem of wild lands.

Fire damage to the structure is not the only damage done during a fire. A study published by the American College of Chest Physicians has confirmed that smoke inhalation from major fires has a prolonged, negative effect on pulmonary function. All of the subjects were survivors of a fire in a bar frequented by older teenagers. After six months, the most frequent clinical symptom was productive cough, with two subjects having bloody tinges in their mucus.

Because of the chemical compounds present in building and other materials such as paint, there is a possibility that longer-term effects on the eyes and the lungs could occur. The probability of this occurring is reduced if immediate attention is given to the victim, but those who have grave lung damage at the time of exposure may develop respiratory tract problems that need long-term medical treatment.

Depending on the nature of the fire, some of the more common smoke pollution byproducts may be toxic gases like carbon monoxide, hydrogen cyanide, hydrogen fluoride, and hydrogen chloride, or particulate matter from the burning materials. Breathing one or more of these gases or substances can lead to unconsciousness or to some kind of short or long-term lung damage.