Edmonton has been choking on thick smoke from B.C. wildfires since Thursday and officials say the haze will likely last until at least Sunday. Worst of all, it’s causing health problems, says Dr. Andre Corriveau, chief medical officer of health for Alberta. Corriveau says people should avoid physical exertion and consider staying inside as the number of elderly and asthma-afflicted residents arriving at hospital emergency rooms has spiked. Despite the warnings to stay inside, the Canadian Derby Marathon, the Dragon Boat Festival and the International Fringe Festivals are all planning to go ahead this weekend.