Emergency response research

This page contains abstracts of research on emergency response done by the Transportation of Dangerous Goods Directorate.

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Effectiveness of mercury spill remediation techniques – February 6, 2020

Common products like thermometers and fluorescent lights can cause mercury spills when broken. After mercury is spilled, it evaporates and forms toxic vapours which can cause long-term health problems. Two treatments taken from the literature suggested to clean mercury spills by:

  • physical removal of mercury beads, then covering the spill with sulfur powder
  • physical removal of mercury beads, then wiping the spill with vinegar followed by hydrogen peroxide in concentrations available to the public

The study investigated how effective these treatments are at limiting mercury vapour formation.

For each treatment, the concentration of mercury vapours was analyzed using two methods; the first method took measurements at set intervals, while the second method measured continuously. Gravimetric analysis is a common technique for measuring masses in mixtures and was used to analyze the unreacted mercury after each treatment.

The study compared the concentration of mercury vapours to the baseline vapour pressure of mercury. The study also explored the effect of stirring on the reaction rate for each treatment. The key takeaways are:

  • For mercury that isn’t treated, the maximum amount of vapours in a closed environment is reached in a few hours. At peak concentration, the levels of mercury vapour is outside of the safe limits for human exposure. When mercury is stirred on its own with no treatment, the vapour gets to its maximum concentration within an hour.
  • When the mercury is treated with sulphur powder, the concentration of mercury vapour is lowered. However, the amount is still higher than safe limits. The reaction is also very slow, which can take several months to finish.
  • When the mercury is treated with vinegar and hydrogen peroxide, the concentration of mercury vapour is also lowered, but remains higher than what is considered safe. The reaction is slow and creates mercury acetate, which is hazardous by skin contact. This mixture also releases oxygen, which can pose a risk in the case of a fire.

Overall, the study shows that the sulphur and vinegar-hydrogen peroxide treatments are ineffective at reducing mercury vapours in the air to safe levels in a reasonable amount of time.

Based on the findings, the Canadian Transport Emergency Centre (CANUTEC) recommends physical removal of mercury beads and ventilation of the affected area for cleaning small, uncomplicated, mercury spills. For larger spills or in case of doubt, professionals such as CANUTEC should be consulted.

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To get a copy of the report, please contact us.

Catalogue Number: T86-60/2020E-PDF
ISBN: 978-0-660-33717-3

Hypochlorites reactivity – May 19, 2020

Hypochlorites are found in many common cleaning products, such as bleach and swimming pool water treatment products. They are generally stable, but they can be harmful to your health if you don’t use them correctly. If you mix them with other cleaning products, or expose them to small amounts of water, they may release toxic chlorine gas.

Transport Canada studied how some hypochlorite products react based on factors like temperature and mixing speed. To test for potential chlorine release from liquid hypochlorites, we conducted experiments where a strong acid, hydrochloric acid (HCl), was slowly added to different liquid hypochlorites until chlorine gas was produced. To test solid hypochlorite products, we added small amounts of water and monitored for any gas produced or temperature change over a period of time.

The liquid hypochlorite study found:

  • the reaction starts fast, releasing chlorine gas very soon after the acid is added
  • the amount of chlorine gas produced from the reaction was toxic for humans if allowed to accumulate in a closed space with no ventilation
  • if the hypochlorite is not mixed thoroughly with a strong acid, the reaction can continue releasing chlorine gas up to 2 hours after they are combined based on the products tested
  • as the temperature increases, the reaction occurs faster releasing chlorine gas at a faster rate

The solid hypochlorite study found:

  • the reaction between solid hypochlorites and water produced little to no chlorine gas
  • mixing the solid hypochlorite product in water did not create any significant amount of gas, even at different temperatures and mixing speeds
  • the reaction releases heat and oxygen, which can increase the risk of a fire near an ignition source

The Canadian Transport Emergency Centre (CANUTEC) used these results to develop questions to ask the public during a hypochlorite incident, and aid first responders in predicting potential chlorine release. CANUTEC also used these results to develop recommendations for many situations involving solid and liquid hypochlorites. You should consult CANUTEC for incidents that may involve hypochlorites.

Learn more

To get a copy of the report, please contact us.

Catalogue Number: T86-63/2020E-PDF
ISBN: 978-0-660-34918-3

Contact us

Safety Research and Analysis Branch
Transportation of Dangerous Goods Directorate
Transport Canada
Email: TC.TDGScientificResearch-RecherchescientifiqueTMD.TC@tc.gc.ca