For cyclists, car doors are a constant threat. And for the first time, Montrealers are learning how often.

Last year, 105 cyclists were hit by car doors, and two were killed in so-called "dooring" accidents, say Montreal police.

“Most accidents go unreported, so that's just a drop in a bucket,” said Geoffrey Bush of the Montreal Bike Coalition.

Several Montreal bike associations and the police have launched a "dooring" awareness campaign. The message to cyclists is to stay at least a metre away from parked cars, while they’re asking drivers to be in control of their doors.

Montreal police say that drivers should reach across their bodies with their right arm to open their doors, forcing them to look at their side-view mirrors and check their blind spots.

Motorists could face fines, $30 dollars plus fees, if they're not careful.

“So if you open (the door), even if you don't hit a cyclist, if it was (done) dangerously you could receive a ticket,” said Nathalie Valois of the Montreal police’s bike safety division.

Many U.S. cities have dedicated campaigns and implemented strict fines to reduce dooring accidents.

The penalty in Chicago, for example, is $1,000.

Cycling activists in Montreal would like higher fines but say developing safer habits is most important -- and could be the difference between life and death on the roads.