What is the potential risk?

Some commercial suppliers market systems for using ozone and/or hydroxyl radicals in commercial washing machines. These chemicals are introduced into the wash water to disinfect and kill bacteria.

Depending on the concentration of ozone, exposure can result in acute respiratory health problems or even death. Mild to moderate symptoms can include coughing, a sore or scratchy throat, damage to airways, and other related health issues. Exposure can vary based on duration and intensity of the work. A commercial laundry worker who is loading and unloading a washing machine may be exposed to high levels of ozone. Fatal injury can occur from only a brief exposure when concentration levels reach 5 ppm.

What is ozone?
Ozone is a highly reactive and unstable gas that can be formed by a reaction of ultraviolet light or electricity with oxygen. It is usually produced onsite for immediate use as a mixture with air or oxygen, in an ozone generator, as it is too reactive and unstable to store as the pure gas.

Ozone is heavier than air but it is usually diluted and will not necessarily settle to lower levels. Pure ozone has a slightly bluish color but a dilute solution in air will be colourless and may have a distinctive odour (like the smell in the air before a thunderstorm).

Ozone is only slightly soluble in water, so when a solution containing ozone is placed in a washing machine, some ozone gas will be present in the space above the wash water. Agitation or heating of the solution will result in even more ozone being released.

What are hydroxy/radicals?
When ozone is dissolved in water, a complex series of reactions takes place, producing short-lived chemicals. One of those chemicals produced is the hydroxyl radical. Some manufacturers emphasize hydroxyl radicals in their marketing materials, implying that ozone is not present. But there is a risk that hydroxyl radicals will react in a water-based solution and will re-form ozone.

Who is at risk?

Working around commercial laundry machines can put workers at risk of exposure to ozone at dangerous levels, especially when reaching into machines to remove laundry. Workers in the following industries may be at risk:

• Health care
• Hospitality
• Commercial laundry facilities

How can I reduce the risk in my workplace?

Under section 26(b) of the Workers Compensation Act, the supplier must provide enough information to ensure the customer is following health and safety requirements for operating this equipment. Before you consider purchasing and installing an ozone generator, you need to discuss these requirements with the supplier.

The following information highlights sections in the Occupational Health and Safety (OHS) Regulation that are most relevant to this risk. The employer must do the following:

• Conduct a risk assessment for their workers using this equipment (s. 6.118).
• Develop written safe work procedures so that their workers understand how to safely use this equipment (s. 6.120).
• Train their workers to ensure they are capable of following these work procedures (s. 6.121).
• Ensure ozone equipment has a properly ventilated enclosure (s. 6.122) and that the ventilation system exhausts directly to the outside (s. 6.124(a)).
• Maintain a monitoring and alarm system to monitor the ozone levels (ss. 6.128(1) and (2)) and ensure the results from the monitoring system are visible from outside of the enclosure (s. 6.123).
• Use an emergency shutdown device for the ozone system that can be activated from outside the enclosure (s. 6.126).

Where can I find more resources?

You can access the following resources on worksafebc.com:

• Book: Ozone Safe Work Practices
• OHS Regulation: Part 5, Chemical Agents and Biological Agents, and Part 6, Substance Specific Requirements.

Learn more about managing risk in your workplace.