Just when it seemed that Lower Mainland air was safe to breathe, there's a new advisory from the regional district.

It's been issued this morning (August 26) due to high concentrations of fine particulate matter in Metro Vancouver and the Central Fraser Valley today.

An existing air quality advisory remains in place for the Eastern Fraser Valley, including Agassiz and Hope.

"Despite cool and damp weather yesterday and today, smoke from wildfires both within and outside the region has moved into all parts of Metro Vancouver and the Fraser Valley," Metro Vancouver said in its statement. "This has resulted in elevated levels of fine particulate matter that exceeded our air quality objectives throughout the region during the overnight period. Elevated levels of fine particulate matter are expected to persist until there is a change in weather or fire conditions."

Fine particulates are 2.5 microns or less in diameter and can lodge deep inside the lungs. They can also be found indoors because of their small size.

Anyone with chronic medical conditions, including lung and heart disease, is being advised to postpone strenuous exercise.

"If you are experiencing symptoms such as chest discomfort, shortness of breath, coughing or wheezing, follow the advice of your healthcare provider," Metro Vancouver stated. "As we are in the summer season with warm temperatures, it is also important to stay cool and hydrated. Indoor spaces with air conditioning may offer relief from both heat and air pollution."