Firefighters may respond to fires in or around agricultural silos.


Rescue situations may cause safety issues for responders, due to confined spaces or the risk of explosion.

Actions for employers

Employers should:

  • identify the locations and types of any agricultural silos in their response area
  • develop procedures for responding to silo incidents

Types of silos

There are three types of vertical silos used in agricultural areas in Ontario. Each can pose safety concerns to the firefighters in a fire or rescue situation.

Conventional silo

These silos are made of banded concrete slabs, poured concrete or steel plates. The silos unload from the top.

Rescues may be required for farm personnel who are required to enter silos to service unloader equipment.

Oxygen-limiting silos

These silos are made of poured concrete or steel plates. These silos are unloaded from the bottom.

There is not enough oxygen to support life in these silos. Farm personnel do not need to enter the silo during unloading or when crops are in the silo. However, there have been cases where people have entered and have collapsed due to low oxygen or the gases produced by the crop preservation process.

Converted oxygen-limiting silos

These silos are oxygen-limiting silos that have been converted to a conventional silo. These silos are unloaded from the top but may still make use of bottom unloaders. These may contain similar hazards to both oxygen-limiting and conventional silos.

Responding to agricultural silo incidents

Employers should consider these potential hazards when developing procedures for responding to agricultural silo incidents:

  • silo gases may be toxic and nitrogenous products in preserved crops give off toxic gases when burning
  • deficient oxygen atmosphere
  • airborne grain dust and methane from the microbial decomposition of organic products can be sources of fuel for an explosion
  • explosions of both conventional and oxygen-limiting silos during fires are possible

Employers should consider these safe practices:

  • use extreme caution when responding to these incidents
  • do not enter the structure to extinguish fires or conduct a rescue unless the identified hazards and associated risks are mitigated or removed
  • identify the silo type, product, hazards and the extent and degree to which fire and heat are transferred within the silo and the surrounding feed rooms or buildings
  • use thermal imaging cameras, if available
  • establish an adequate water supply before commencing any suppression operations
  • consider using firefighting foam, depending on the products involved

In a conventional silo:

  • apply only as much water or foam as necessary to ensure the containment of the fire
  • large amounts of water in the structure may cause a collapse
  • do not climb the chute or outside ladder as the system may fail due to heat damage
  • a fire should not be considered extinguished until the structure is empty

In an oxygen-limiting or a converted oxygen-limiting silo:

  • do not open any hatches or doors, nor spray water into the structure, as the introduction of water and oxygen may result in an explosion
  • consult the silo manufacturer for advice on proper procedures to extinguish these fires

Rescues from agricultural silos

Rescues from agricultural silos may require rope rescue. For more information on rope rescue, refer to Guidance note 6-4: Rope rescue. Where the situation may involve confined spaces, refer to Guidance note 6-5: Confined space rescue.

Note: Incidents involving industrial dust collectors, hoppers and bins may require different tactics and approaches from those described in this guidance note. Please refer to Guidance note 6-27: Industrial dust collectors, hoppers and bins.

 Applicable regulations, acts and standards


  • Occupational Health and Safety Act
    • clause 25(2)(a) for providing information and instruction to a worker
    • clause 25(2)(d) for making workers aware of hazards
    • clause 25(2)(h) for taking every precaution reasonable in the circumstances to protect workers


Read firefighter guidance notes: