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Explosives Hazards in Ontario Mines

Safe At Work Ontario
  • Issued: July 9, 2014
  • Content last reviewed: July 2014

Disclaimer: This resource has been prepared to help the workplace parties understand some of their obligations under the Occupational Health and Safety Act (OHSA) and regulations. It is not legal advice. It is not intended to replace the OHSA or the regulations. For further information please see full disclaimer.

Improper storage or handling of explosives can result in serious injuries or death to mine workers. An incident involving a storage area or surface blast can even injure members of the public and damage property outside an underground mine, open pit mine or quarry.

Workplace health and safety is an important issue for Ontario mines. Mines with safe practices involving explosives generally have fewer incidents.

The Ministry of Labour enforces and promotes awareness of the need for mines to comply with legislated requirements and use, handle and store explosives safely.


Explosives are used to help break ore and rock into smaller pieces so they can be more easily removed from a mine for processing. The technology and products used for blasting have greatly improved since explosives were first used in mines in the early 17th century. However, the potential for harm is still great.

Ontario has about 40 underground mines and hundreds of surface mines and quarries that employ about 25,000 workers. Most of these mines use explosives.

A wide variety of minerals are extracted from Ontario mines, including copper, nickel, gold, salt and diamonds. Rocks and aggregates, for use in construction, are mined in surface quarries.


Mining employers and supervisors are responsible for safe practices involving explosives and for ensuring that workers are able to safely use explosives. These duties are set out in the:

Safe practices must include the following:

Maintenance / inspection of explosives magazines and equipment
Magazines (buildings, locations or containers) that store explosives must be maintained in clean and orderly condition. Mobile equipment and tools must also be maintained in good and safe condition if they are used in processes involving the handling of explosive products.

Explosives inventory methods
Employers must use measures such as keeping logbooks to control inventories of explosive products underground and on the surface. They must also have procedures in place to ensure the oldest explosives are used first. In addition, inspection reports must include details on the quantities of explosives stored at the time of inspection. These measures are required because the quality of explosives can be degraded if they aren’t used in a timely fashion. This can make them potentially volatile and hazardous. Workers can also be at risk if incompatible products are improperly mixed during blasting operations.

Procedures for safe disposal of damaged explosives
Employers and their Joint Health and Safety Committees develop written procedures for the safe disposal of damaged explosives. These procedures must be communicated to workers and are needed to ensure workers don’t attempt to use damaged explosives. They are also needed so that workers assigned to dispose of them are aware of their condition. Damaged explosives can be dangerous.

Proper handling during transport and use
Employers must develop proper procedures for workers handling explosives when the explosives are being used and transported. The movement of explosives between magazines and workplaces must occur without delay. Vehicles carrying explosives must always have the right of way. Measures must be taken to ensure explosives are never left unattended and/or improperly disposed of.

Ministry reporting
Employers must notify the Ministry of Labour of the use of explosives and installation of surface explosives magazines. The employer must notify the ministry of any incident involving the mishandling of explosives. The ministry must also be notified of an uncontrolled or unexpected explosion and any defective explosive products.

Worker training
Any worker that uses or handles explosive products or who may be affected by their use must be trained in all the relevant safety procedures. Workers must successfully complete the relevant Common Core Training modules set out in Section 11 of the mining regulations. The training must ensure all workers are familiar with what explosive products look like and the procedures to be followed if any are found in incorrect places.

Compliance information

Toll-free number

Call 1-877-202-0008 any time to report critical injuries, fatalities or work refusals. Call 8:30 a.m. to 5 p.m., Monday-Friday, for general questions about workplace health and safety. Always call 911 in an emergency.

Disclaimer: This web resource has been prepared to assist the workplace parties in understanding some of their obligations under the Occupational Health and Safety Act (OHSA) and the regulations. It is not intended to replace the OHSA or the regulations and reference should always be made to the official version of the legislation.

It is the responsibility of the workplace parties to ensure compliance with the legislation. This web resource does not constitute legal advice. If you require assistance with respect to the interpretation of the legislation and its potential application in specific circumstances, please contact your legal counsel.

While this web resource will also be available to Ministry of Labour inspectors, they will apply and enforce the OHSA and its regulations based on the facts as they may find them in the workplace. This web resource does not affect their enforcement discretion in any way.