Fires are arguably the biggest risk of residential heating. Roughly half of residential fires go without a conclusive explanation for its cause. That said, 16% of U.S and 20-25% of worldwide residential fires come from residential heating systems, according to NFPA.

Heating systems have a variety of fuels and technologies, the most popular of which are gas, electricity, oil, coal, wood and solar heating. About 51% of residential units in the U.S. utilize natural gas for heating purposes; 30% of homes are heated with electricity; and 9% make use of fuel oil. The remaining 11% are heated with bottled fuel, wood, coal, solar, geothermal, wind or solar energy.

Between 2009 and 2013, estimates say heating equipment was involved in an around 56,000 reported U.S. home structure fires, with associated losses of 470 civilian deaths, 1,490 civilian injuries and $1 billion in direct property damage.

That said, other dangers are prominent as well, such as carbon monoxide or even health effects.

As millions of people in their northern hemisphere trudge into the the scrip autumn and chilly winter seasons, here are the top risk factors to be aware of this year.

1. Space heaters

Space heaters (stationary or portable) are the most common of all heating equipment used. They are responsible for 40% of fires. In addition, they are the cause of about 86% of deaths, 78% of injuries and 54% of direct property damage.

Space heaters are convenient, but also risky. They need adequate space around all sides and should never be placed near easily flammable materials, like fabrics and papers. Space heaters are also at risk of tipping over or being left on for too long, which can lead to overheating, and also carry electrical risks.

2. Dirty chimneys

Twenty-seven percent of home heating fires erupted because chimneys were never cleaned. Creosote build-up is highly-flammable and is best removed by chimney sweep, who has the right brushes, cleaners and inspection equipment.

3. Electrical hazards

Corroded or frayed wires are electrical hazards. Damaged or old Electric heating elements, thermostats, furnaces and power supplies should be replaced before being used. Electrical malfunctions contribute to 9% of heating home fires overall. And 35% of fires were from electrical heat sources.

And leaking fuel lines introduce combustible liquids or gases into a residential space. Together it is a recipe for explosion. In addition, broken heat exchangers can exhaust carbon monoxide, another danger.

4. Clutter

Heating systems need enough area to both draw in cold air, and disperse hot air to a comfortable concentration. If air intake is blocked by furniture, items or household mess, it can cause the heater to overheat; if the exhaust is blocked, items could be roasted to an ignition point. Crowded heating equipment is a contributing factor in more than 50% of heating fires.

5. Negligence

Although leaving heating equipment without monitoring in itself is not a cause of fire, 7% of fires could be prevented or contained if better heating supervision had been in place.

6. Fuel leaks

Any equipment powered by gas or oil can be a risk for this home heating hazard. If not maintained, furnaces and gas heaters can develop leaks that introduce a flammable substance into the environment.

Natural gas is colorless and odorless. Gas supplier companies add mercaptan chemicals to the gas to make it smell like rotten eggs. If not properly maintained, gas furnaces and ovens can cause leakage of small amounts of natural gas. If there is not proper ventilation, a spark or switching on the electrical socket can ignite the accumulated gas.

Meanwhile, heating oil is a red-dyed diesel fuel that is a hazardous material. Exposure to spills can be hazardous to respiratory health, in additional to fire risks.

Any fuel leak is exponentially more dangerous in the presence of an electrical fault.

7. Water heating solutions

Home heating systems utilize water and steam to maintain centralized temperature control. Water impurities and acidity can accumulate after an extended period and damage your boiler system. It results in water leaks, “steam hammer” and hydronic system failure.

8. Carbon monoxide poisoning

Carbon monoxide (CO) is a lethal gas consisting of one oxygen and on carbon molecule. It is colorless, odorless and tasteless gas, which is byproduct of heating fuel combustion. Many furnaces exhaust this through pipes or chimneys, another great reason to inspect them and keep them clean. This can also be introduced by a broken heat exchanger in some systems.

A CO monitor can be a life saving investment if its batteries are replaced on a yearly basis.

9. Injuries and burns

Direct heat sources, such as wood and pellet stoves, fireplaces and other direct heating systems, will create hot surfaces. Fair Warning estimated than 2,000 children were burned by fireplace glass between 1999 and 2011.

10. Dehydration and allergies

Dust particles may be accumulated on heating systems during the summer, and when activated will blow dust particles throughout a room and home. Individual sensitivity will vary, so those sensitive to dust should be sure to clean systems before activating them.

Some heating systems also have a tendency to reduce the atmospheric moisture in the home. Residents may experience additional thirst or drier skin. This can be countered by the addition of a humidifier.