A Canadian mountaineer who climbed Mount Everest twice says overcrowding and inexperience are causing renewed concerns about safety during the current climbing season.

The world’s highest peak is under new scrutiny after four people died on the mountain in four days. Three were climbers who died of altitude sickness or exhaustion. The fourth was a Sherpa who fell to his death. Two Indian climbers are currently missing, and more than 30 people have developed frostbite or have become sick near the summit in recent days.

Last year, 19 people were killed when an avalanche hit the Everest base camp. And in 2014, 16 guides were killed in an avalanche in the Khumbu Icefall. The deadly incident resulted in protests by Sherpa guides and their families that brought the climbing season to a premature end.

Jim Elzinga, an alpinist who led the history-making Canadian Everest Light expedition in 1986, says a lot has changed since the 90s, when the Nepalese government realized it could make more money by enabling commercialized ventures to take place on Everest.

Before that, the government allowed only one or two climbing expeditions on the mountain per season.

“You pretty much had the mountain to yourself,” Elzinga said in an interview on CTV’s Canada AM on Tuesday.

Today, Elzinga said, there is a “ranking” of operators who offer a premium product, and other operators who come in to try to “undercut” the businesses.

“That’s just opened up the opportunity for more people to come and climb Everest,” Elzinga said, adding a climber could be looking at a range of prices from $20,000 to $80,000.

And, like anything else, Elzinga says, “The less you pay, you’re probably going to have not as great service as you would with a premium operator.”

Adventurers who are unprepared for the difficult conditions on Everest are also causing renewed concerns about health and safety on the mountain.

“I think it goes without saying, if you want to climb Mount Everest, you want to be in the best possible physical condition you can be,” Elzinga said. “But conditioning is only one aspect of it, just having the ability and knowledge to climb and that’s where I think a lot of these problems come from.”

Some climbers also come with the expectation that their Sherpa guide is “going to take care of them,” Elzinga said.

At base camp, climbers have access to food and proper oxygen.

“When that breaks down, or when their oxygen starts running low, that increases their exposure, and with that, their risk,” Elzinga said.

Overcrowding could also be leading to trouble on Everest. Elzinga said there could be “well over” 100 hundred people going to the summit during peak climbing weather periods.

“With that, you get people that aren’t strong enough, people trying to climb over other people,” Elzinga said. “That just leads to all sorts of issues.”