VANCOUVER It’s hard not to notice Metro Vancouver’s hazy horizon. Blue skies have been replaced with a brown fog. It’s something the region has experienced during previous summers, but this year, officials say the haze is being caused by something different. Portions of the region are under an air quality advisory, first put in place on Saturday for eastern Metro Vancouver and the central Fraser Valley Regional District. But on Tuesday afternoon, the Metro Vancouver authority said the advisory would be expanding. “The Air Quality Advisory for ground-level ozone is being expanded to include the eastern Fraser Valley Regional District,” reads a statement from Metro Vancouver.