A 0.5 per cent additional sales tax levied just in Metro Vancouver would spur more consumers to shop outside the region, raising questions over how the proposed tax will be implemented. So-called "leakage" of spending east to the Fraser Valley or south to the U.S. is a concern, Metro mayors admit, and is likely to be most acute for businesses in areas close to the TransLink boundaries - Langley, Maple Ridge and South Surrey.