The record-breaking temperatures in Montreal prompted calls Tuesday by one of the city's opposition parties to install air conditioning in the public transit system.

With the temperature reaching 32 degrees Celsius, and 40 with the humidex, Projet Montreal said the installation, which they estimate to cost $50 million plus running costs, is well worth it during the sweltering summer months.

The installation would last for 50 years, said advocates of cooler public transit.

"We don't waste money by investing in quality. It's our bet on the future," said Projet Montreal leader Richard Bergeron.

New York, Barcelona and New Delhi have air conditioning in their subways, and Gatineau, Ottawa and Terrebonne have air-conditioned buses, said Project Montreal.

Part of their goal is to coax more drivers out of their cars.

"Why not give them the experience (of air conditioning, so) that they won't want to buy a car?" said Projet Montreal councillor Francois Limoges.

The Societe de Transport de Montreal said the cooling system would cost much more than the proposed $50 million.

"It's a poor use of public funds," said Marvin Rotrand, STM vice president.

The transit commission argues air-conditioned metro trains would push more heat into metro tunnels, making it more expensive and impractical.

The STM said it is already working to cool down the metro with new ventilation systems for its latest metro cars, and it will test out air conditioning on some heavily trafficked bus routes.

"We want to test the clientele's appreciation," said Michel Labrecque, the transit commission's board chairman.

A cool temperature will definitely improve the ride for passengers on hot days, said Tommy Mouhteros, spokesperson for the STM bus drivers' union.

"We had passengers on the 69 who got off the bus (Tuesday) and said they were walking because it was too hot on the bus," he said.