Residents and businesses near nuclear power plants must be provided with potassium iodide pills as a precautionary measure in case of an emergency, the Canadian Nuclear Safety Commission said Friday.

The pills, which must be preemptively distributed in conjunction with local governments, protect against nuclear exposure by preventing the human thyroid gland from absorbing radiation.

The measure was included as part of two new regulations published by the CNSC this week intended to “enhance regulatory requirements in nuclear emergency management” the watchdog’s website said.

Nuclear energy operators must provide the pills to “all residences, businesses and institutions” that could be at-risk of exposure from a radiation plume potentially released during an emergency.

While the specific area covered by this definition differs from site to site, it is generally a radius of between eight and 16 kilometres from a nuclear power plant.

Post-Fukushima pressure

In Canada, mass distribution of pills has already occurred in New Brunswick and Quebec, but not in Ontario, where the majority of the country’s nuclear power plants are located.

The CNSC had come under pressure from international environmental groups such as Greenpeace to improve safety standards in the wake of the 2011 Fukushima disaster in Japan. Many other countries have had a system of mandatory pre-distribution of potassium iodide pills for years.

“The new regulatory documents address lessons learned from the Fukushima nuclear accident and incorporate international post-Fukushima best practices and guidance” for Canada’s nuclear power corporations, the CNSC’s website said.

Nuclear power operators reportedly expressed concerns earlier this year over how the new regulation will be implemented and the size of the area that will be covered. In heavily-populated regions near nuclear power plants, each additional kilometre would translate to handing out pills to tens of thousands of residents.