Hydro-Québec also studies the potential human health hazards inherent in its operations and takes steps to mitigate them. For example, we know that reservoir impoundment temporarily increases fish mercury levels and that they return to normal after 10 to 35 years. This phenomenon has been closely monitored for many years and fish consumption recommendations are issued as needed.

In addition, noise from our facilities can be a nuisance and we endeavor to minimize it, especially in residential areas. For example, quieter power transformers are installed when work is done on transformer substations. Should at-source reduction prove insufficient, we apply noise reduction measures wherever possible.

Hydro-Québec operations and human health – Current situation
Issue Research Status Conclusion
Health effects of EMFs generated by live conductors and electrical equipment Over the past 40 years, hundreds of epidemiological studies and tests have been conducted. The opinions of certain large organizations are outlined in the brochure The Power System and Health – Electric and Magnetic Fields. To date, no EMF-related health effects have been found but Hydro-Québec is still monitoring knowledge and participating in studies conducted elsewhere in the world. The company is continuing to study the effects of high-intensity magnetic fields on humans and of high-electric-field interference thresholds on the operation of medical implants like pacemakers.

Public health authorities in Québec and Canada consider it unnecessary to take extra measures to protect oneself from exposure to EMFs generated by power lines beyond the set exposure limits.
Health effects of the temporary increase in fish mercury levels after reservoir impoundment Since the late 1970s, Hydro-Québec has led an extensive research program in conjunction with a number of partners. Mercury levels in developed environments are not harmful to fish-eating fish, birds or mammals.

Hydro-Québec works with public health authorities to develop fish consumption guides so that anglers can benefit from the nutritional value of fish while avoiding mercury-related risks.
Health effects of noise from transmission lines and substations The issue of public sensitivity to substation noise has been poorly documented. Noise is not spontaneously associated with power lines.

Noise has a number of documented health effects. Besides potentially damaging hearing, it can disturb sleep, interfere with cognitive processes in children and raise the risk of cardiovascular disease.
Noise generated by lines and substations is relatively limited and cannot cause hearing loss. New substations are designed to meet very strict criteria so the noise produced has no significant effect on the health, activities or behavior of people who live near our facilities. We take the audible noise produced into consideration when determining the location of new 315-kV or higher-voltage power lines.

We currently have noise-related data on about 50% of the substations located close to inhabited areas. None of these substations produces noise levels high enough to cause hearing damage in local residents. However, some facilities generate noise levels high enough to cause discomfort and disturb sleep. New substation equipment must also comply with noise criteria and is tested before being put into service.

Complaints regarding noise from existing power lines are very infrequent. New lines are located so as to comply with the established noise criteria.


  • The new Fish consumption guide of the Gros-Mécatina region was distributed in the community. Including the results of the mercury follow-up in Robertson reservoir, the guide was produced in cooperation with the Centre intégré de santé et de services sociaux de la Côte-Nord. Available online [PDF 4.0 Mb] (Côte-Nord)
  • Noise barriers were installed on two transformers at Heriot substation in Drummondville. A subsequent study found that noise was reduced by 13.3 dBA on the first transformer and by 15.4 dBA on the second. (Centre-du-Québec)
  • In conjunction with the Sûreté du Québec, an information day was held at Carillon generating station to inform the media of the danger zones and potential hazards for anglers and boaters who venture too close to the facility. (Laurentides)
  • A presentation on mercury was held at the Ekuanitshit health center, followed by an open-house day. Innu community members were informed about mercury (including the confirmed benefits of eating fish despite the presence of mercury) and the coming steps in the follow-up on fish mercury levels in Romaine complex reservoirs. (Côte-Nord)
  • New trials were conducted with the Montreal Heart Institute to ascertain whether electric and magnetic fields interfere with pacemakers or cardiac defibrillators. The study simulated the type of electric fields encountered beneath high-voltage power lines. Conclusion: In the majority of cases, the devices operated normally, with no interference detected. Interference was observed in rare cases but remained minor and did not put the wearer’s life in jeopardy. The results will be used to document any possible scientific publications on electromagnetic interference ranges and pacemaker/implantable defibrillator resistance to 60-Hz electric fields.

See also