TORONTO — When the clock struck midnight this morning, truckers’ carriages didn’t turn into pumpkins, but much to some drivers’ dismay they did transform into non-smoking workplaces.

As of 12:01 a.m. today, Ontario’s controversial new Smoke Free Ontario Act took effect. The legislation bans all smoking in enclosed public spaces and workplaces, which under provincial law, includes — you guessed it — a truck cab too.

Most company drivers who like to light up while on the road might want to tell the government to butt out, but that’s exactly what they may be hearing in the coming days from fleet owners who are now required to ensure employees abide by the prohibition; post non-smoking signs in all applicable areas of the workplace; and remove all ashtrays in work zones.

Bosses caught not complying with the law could face fines anywhere from $5000 up to $300,000, depending on the severity and number of breaches.

Fleet owners are required to tell drivers to butt out. But will they?

(Quebec — once regarded as Canada’s last refuge for smokers — also enacts a similar anti-smoking workplace bill today, although it’s less clear how that province defines company vehicles).

Owner-operators for the most part are exempted from the rule. Independent truckers may light up in their own trucks as long as no one else — not even a part-time driver, spouse, or friend — enters the cab at any time, including off-duty hours.

However, carriers are responsible for making sure their contracted operators don’t puff away on company property, although the business is not required to oversee the smoking habits of owner-ops once they drive away.

There also remains some doubt whether the law applies to federally regulated carriers. While Ontario — which doesn’t draw any distinction between working and non-working hours — clearly defines a workplace as ” a building or structure or conveyance where employees work whether or not they are acting in the course of their employment at the time” the federal Non-Smokers Heath Act only implies that a truck cab is at par with an office.

Furthermore, the federal rule allows employers to designate certain areas as smoking areas, meaning drivers may be permitted to smoke in the vehicle, if the employer okays it and no other worker uses the truck.

Whether the federal law trumps the Queen’s Park mandate for federally-regulated companies is for the lawyers and labor boards to decide in the coming months. Trucking groups like the Ontario Trucking Association are currently seeking clarification of such an application to the rule, but in the meantime employers are advised to follow the provincial law as it’s written or risk penalties.

Nevertheless, many in the industry doubt whether the Ontario law is even enforceable when it comes to mobile workplaces. Smoking drivers may lose their ashtrays (and non smokers may have to find somewhere else to dump their change), but that won’t stop many from sparking up anyway — especially once they’ve pulled away from head office.

When the topic came up during a discussion this week at the Canadian Fleet Maintenance Seminar, one safety and compliance manager at a large Ontario carrier suggested many employers would likely look the other way in order to keep drivers in the seats.

“Besides, what’re they going to do have road-side inspections for smoking too?” he asked sarcastically.