Willems had a form of cancer linked to asbestos called mesothelioma, which he believed he contracted while inspecting a number of older food plants in Saskatchewan.
Family members confirmed Willems died on Thursday.
His stepson, Jesse Todd, said Willems had been sedated for the last 48 hours and last spoke Tuesday.
"He gathered the family around and said he'd had enough and he was tired," Todd said. "[He] just wanted to go in peace."
Willems was a proponent for the creation of a registry of buildings that contain asbestos.
Last week, the Opposition NDP brought that issue to the Saskatchewan government.
However, the minister responsible for workplace safety, Don Morgan, said a registry would not be a good idea.
Virtually all public buildings constructed before 1980 contain asbestos and many built since also have it, Morgan noted in response to the NDP.
Morgan suggested a registry of buildings with asbestos might be incomplete and would therefore create a false sense of security.
30-plus years inspecting buildings
In 2011, at the age of 58, Willems had a lung removed.
Willems was a building inspector for more than 30 years and believed his exposure to asbestos was related to inspections he did on plants while they were being renovated, especially during the removal of pipes with asbestos insulation.
“When the light hit the right way you could see the fibres in the air," Willems told CBC News earlier in 2012.
He said no one seemed to be concerned at the time about the dangers of breathing in the fibres, and that a registry would help workers to be better informed about hazards.
Todd said that Willems tried to make a difference.
"He just hopes that all this does bring about change in the end. You know, this was his wish."
The World Health Organization estimates that 107,000 people die each year from asbestos-related disease.Suggest a correction