It is critically important for companies to establish and follow safe guidelines for using portable heaters. Without them, portable heaters can become workplace fire hazards.


  • Ensure electronic flame sensors or pilot safety valves are in place.
  • Examine cords or electrical connections for damage.
  • Inspect for damage or fuel leakage following long-term storage.


  • Place heaters on a non-combustible surface that extends four feet in front of the unit, unless approved otherwise by the manufacturer.
  • Remove all combustible materials near the unit.
  • Establish a three-foot safety perimeter around the heater.


  • Ensure there is adequate ventilation in the area where you plan to use the heater.
  • Provide mechanical ventilation when the natural supply of fresh air is inadequate.
  • Verify the unit does not deplete oxygen in the area.
  • If you’re using the heater in an enclosed space, use an appropriate carbon monoxide detector.


  • Maintain a fire extinguisher nearby.
  • Verify that the heating unit is off and cool before you refuel it.
  • Never refuel indoors or within 50 feet of a building.
  • Turn off portable heaters in unoccupied spaces.


  • Develop a plan for portable heater use.
  • Make sure to communicate sound safety procedures for using portable heaters.
  • Consider the jobsite’s conditions and requirements before selecting a portable heater.
  • Make sure all workers know how to use portable heaters safely.
  • Always follow the manufacturer’s specifications.
  • Reference OSHA’s construction standard for temporary heating devices Subpart F, 1926.154.

Download a printable PDF and recording form here.

Members can download the audio version of this toolbox talk here.


Carbon monoxide poisoning is the leading cause of poison-related death in the United States and is responsible for approximately 450 deaths and 20,000 nonfatal injuries every year. Carbon monoxide is referred to as the silent killer because it’s a tasteless, colorless, odorless and non-irritating, poisonous gas that can overcome people exposed to it without warning.

Carbon monoxide blocks the absorption of oxygen into the bloodstream and poisons the red blood cells so they cannot carry oxygen. If tissues and organs don’t receive oxygen, they stop functioning.

In construction, the major source of carbon monoxide is engine exhaust. Gasoline, propane and diesel engines all release carbon monoxide. Some forms of welding and heaters can also produce carbon monoxide.


  • Headache.
  • Nausea.
  • Weakness.
  • Dizziness.
  • Loss of consciousness.
  • Death.


  • Portable heaters.
  • Portable generators.
  • Concrete saws.
  • Compressors.


  • Conduct a workplace survey to identify all potential sources of carbon monoxide exposure.
  • Use equipment in a well-ventilated area, never in an enclosed area.
  • Inspect equipment prior to use.
  • When you’re using gasoline-powered engines or tools outside of a building, don’t place them near air intakes.
  • Limit running time, and don’t let engines idle.
  • Provide employees with small, personal carbon monoxide detectors with audible alarms to wear or install large, mounted carbon monoxide monitors in work spaces.

Download a printable PDF and recording form here.

Members can download the audio version of this toolbox talk here.

Temporary Heating

Originally published 01/03/2018

Before selecting and turning on a heater, make sure the location is appropriate for heater use. Always keep a charged, inspected, ready-for-use fire extinguisher on hand.

There are two basic styles of heaters: forced air and convection. Forced air heaters have a powerful fan that draws air in and then though the heater. These heaters must be used in areas with plenty of fresh air and should be placed carefully in an area free of dirt and clutter because they get very hot.

Convection heaters use natural air movement to heat air as it moves through the heater. No fan is used. These units get very hot, too. They can be used indoors, but there must be a constant supply of fresh air and at least a 36” clearance all around from any combustible material.

Heaters can be fueled by electricity, propane, natural gas or liquids such as Number 1 fuel oil or kerosene.

Electric: Electric heaters are not as common on construction sites as fuel- or gas-fired heaters. An electric heater should be used where heated air must be free of combustion byproducts (like fumes, carbon monoxide and carbon dioxide). An electric heater is useful in a closed space where the supply of fresh air is limited (like a jobsite office trailer).

Liquid Fuel: Liquid fuel heaters typically burn oil and kerosene and are a good source of heat, but they do, however, require ample fresh air ventilation and a constant supply of fuel to refill the heaters.

Some liquid-fueled heaters release exhaust fumes with an oily smell, which can be irritating for workers. It is possible to vent the heater to the outdoors and produce a large volume of heated air free of combustion byproducts. These heaters are sometimes used to heat the air over a new concrete placement in winter.

Propane (LPG)/Natural Gas (LNG): Propane- or natural-gas heaters are lightweight and easy to transport. Both gases are highly flammable and explosive. Use the necessary precautions when handling, storing and using these gases.

Propane is heavier than air. Leaking gas will settle in low-lying areas such as basements and trenches. This can lead to asphyxiation and explosion. Keep propane containers and tanks secured and upright at all times. Natural gas is lighter than air and, if leaking, will rise to the ceiling of an enclosed space. If you smell gas, turn off the heater and do not use it (or any other heater) until you find and repair the source of the leak.

The next time you need to use a portable heater, don’t just grab the first one you see. Think about where it will be used and select the correct heater for the job.

Download the recording form here.