OTTAWA -- Staff at eight major airports across the country will be brushing up on their language skills as the federal bilingualism watchdog prepares to take a closer look at the levels of English and French in Canada's air transport hubs.

But some workers can breathe easy.

Under the Official Languages Act, many retail stores and airport bars don't have an obligation to serve their customers in both languages.

"The regulations make a distinction between essential services in the airport and less essential services," Official Languages Commissioner Graham Fraser said.

"So you have a right to be served in the language of your choice if you are buying food because that's essential, but you do not have a right to be served alcohol in the language of your choice."

Restaurants and cafeterias, car rental services, money exchange offices and duty free shops will be among the businesses checked by Fraser's covert travellers, as will all services including check-in, screening, boarding and public announcements.

According to Fraser's office, businesses that fail the language test won't be named and shamed.

"For the shops, we don't report on the performance of individual shops, but publish a global assessment. The idea is not to single out anybody, but to have an objective, documented impression of the traveller's experience," a spokeswoman for the language commissioner said.

On Wednesday, Fraser announced undercover travellers hired by his office would be checking on the level of bilingualism at airports in Halifax, Quebec City, Montreal, Ottawa, Toronto, Winnipeg, Edmonton and Vancouver. Airports serving more than a million customers a year have to provide service in French and English.

Fraser's report will be tabled in the fall of 2013.