Mayor Rob Ford faces yet another probe into his conduct, this time related to personal criticism he and his brother levelled at Toronto’s top public health official on their Newstalk 1010 radio show.

Dr. David McKeown, the medical officer of health, raised their ire by proposing that Toronto lower speed limits city-wide to 30 km/h on residential streets and 40 km/h on all others as part of a package of initiatives to make cycling and walking safer.

Ford quickly dismissed the idea as “nuts, nuts, nuts,” and then, last Sunday on the radio show, took aim at McKeown himself, calling the official’s $290,000 salary “embarrassing” and promising to “look into it.”

Councillor Doug Ford, calling in from Florida, asked: “Why does he still have a job?”

Councillor John Filion, chair of the board of health, called the Fords’ comments “highly inappropriate” at a meeting Monday and hinted at taking action against them unless they apologized to McKeown.

Filion gave them, via letter, until noon Thursday. He said Thursday afternoon that, hearing nothing, he will formally ask the city’s integrity commissioner to investigate their comments.

“Obviously it’s very important that all members of council and the mayor respect the role of (city) staff, which is to give advice. Members of council can question recommendations and not follow them,” Filion said.

“I do think it’s out of line to discuss a staff member’s continued employment, or their salary, because you don’t like something they’ve recommended,” he said, adding it’s especially true for McKeown who, by provincial statute, must base his advice on the interests of the health of Torontonians.

Filion is basing his complaint on a section of the councillors’ Code of Conduct that states they must be “respectful of the role of staff to provide advice based on political neutrality and objectivity and without undue influence,” and won’t “maliciously or falsely injure the professional or ethical reputation, or the prospects or practice of staff.”

The integrity commissioner is already probing the mayor’s refusal to send official communications to the Star. Also, a city committee has ordered an audit of Ford’s 2010 campaign expenses and, in September, he will be in court on an allegation of conflict of interest related to a February council vote.