Travellers can expect to see extra OPP officers on the roads and waterways this long weekend.

Const. Shawna Coulter of the Essex OPP detachment said the holiday weekend blitz will start Friday.

"This is the second-to-last long weekend of the summer and we've had great weather. So, people are out there enjoying it," Coulter said. "We just want to make sure it's a safe holiday so we do have a stronger presence this weekend."

The OPP said 2012 has been a deadly year on Ontario roads. Police said they have recorded 25 per cent more fatalities compared to last year.

At the same time, blood reserves are strained during the long weekends of summer.

Dr. Ian Chin-Yee heads the blood bank at a London, Ont., hospital.

He said the need for blood increases with car crashes and other trauma injuries.

He said a single car crash victim can quickly lower blood reserves.

"A patient coming in from a serious car accident can use 50 bags of blood. That's 50 different donors to support one patient," Chin-Yee said. "One or two accidents, which often involves multiple people, can drain our blood supply very quickly."

He said donating blood to top up reserves is particularly important over the summer holiday period.

"Donor blood is good for 42 days," Chin-Yee said. "At any one point in time, we are only 3-5 days ahead of being depleted."