Cities from Santa Monica to Paris are jumping to curb the impact of Airbnb on housing affordability. Some are budgeting hundreds of thousands of dollars to identify properties being offered to tourists and return them to the rental pool for local residents.

Airbnb has become the granddaddy of sites used by homeowners to make money by renting out their entire home, or even a single bedroom (either private or shared).

At the end of June, the San Francisco-based company closed a round of $1.5 billion in private funding from hedge funds, mutual funds and private investors for a valuation of $25.5 billion, making it worth more than some of the largest hotel chains.

Critics fear the service is gobbling up listings from local rental markets, tightening accommodation supplies and leading to higher rental prices.

In Vancouver, where the vacancy rate is low and discussions about affordability are fever-pitched, city officials say they are in the early stages of reviewing “actions taken by other cities,” said chief licence inspector Andreea Toma.

During the summer of 2009, only 144 guests used Airbnb to secure a place to stay in Paris. Last year, this number rose to 517,821, according to numbers released by the company.

In one snapshot of the Paris neighbourhood of Le Marais, the number of tourists renting homes through Airbnb outstripped the number of local residents.

“This is astounding and alarming, and perhaps a bit of a warning,” said Karen Sawatzky, a Simon Fraser University masters student who has been researching the impact of short-term rentals listed on Airbnb on housing affordability in this city.

“Vancouver doesn’t draw quite the tourist crush Paris does,” said Sawatzky, but Airbnb listings are on the rise and this June, she counted 3,473.

Some of this explosion has happened due to Airbnb users evolving beyond individual homeowners who occasionally rent out their properties to include investment and management companies.

In Paris, one of the “most prolific hosts” advertises more than 200 apartments, according to the Wall Street Journal.

In Vancouver, Sawatzky found that 1,215 — or 35 per cent of the total listings — are in the hands of just 381 hosts.

Indeed, there are many hosts on the Vancouver site such as Catherine, with only a single listing, a “cozy room near a scenic park” on East 39th Avenue.

But there are also some hosts with a slew of them: Andrew, for example, has 30 condos mostly located downtown. He asks for a minimum three-night stay and charges from $99 to $200 per night.

Another, Nicole, who posts: “We travel often, we love sharing our homes with people from all over the globe, making new friends and memories,” has 16 listings, including a cluster of condos in Yaletown.

Kelly is a host with 22 listings being offered for a minimum 5-day stay. They are mostly condos and a duplex scattered across False Creek, Kitsilano, Marpole, Richmond and Burnaby that are managed by Suite Living Furnished Accommodations, an East Vancouver-based company on Renfrew Street run by Lisa Chan.

The Vancouver Sun spoke to Chan, but she declined to comment.