People in southern Ontario should start preparing now for the potential of smoke hanging over this part of the province during the upcoming wildfire season, one researcher says.”The most important thing is to act early,” said Amy Li, an assistant professor in the department of civil and environmental engineering at University of Waterloo. She suggested taking two important steps: Make sure a home’s centralized HVAC system can recirculate the indoor air for heating and cooling and have high-efficiency filters; and Consider purchasing portable air cleaners that are an appropriate size for the space you want to clean. With wildfires will come warnings about PM 2.5, which is the particulate matter in smoke, Li said. The small particles have a diameter equal to or smaller than 2.5 micrometres. “…exposure to elevated concentrations of PM 2.5 can cause adverse effects to the respiratory and cardiovascular systems,  especially for children, people with respiratory disease or older people,” Li said.