VANCOUVER - B.C. construction unions and contractors have ratified a groundbreaking substance abuse testing and treatment policy that will apply to all unionized construction workers in the province.

The Construction Labour Relations Association and the Bargaining Council of British Columbia Building Trades Unions herald the policy as the first industry-wide pact on substance abuse in Canada.

Drug and alcohol testing will be conducted on employees involved in workplace accidents or near misses, or when there's reasonable suspicion of on-the job impairment.

Drug tests before a worker is hired are also permitted, but those tests are voluntary.

The program checks for alcohol and nine common drugs, including marijuana, but all sides insist the program will only measure current impairment and won't affect the after-hours actions of workers.

Employees who test positive will be barred from the job site until a doctor who specializes in substance abuse has given the okay and those workers will have to undergo follow-up testing for up to two years.