While people may have cut down on their consumption of some fish and other water-sourced foods because of increasing mercury levels that affect water quality, new research suggests that urban residents may face similar problems from the air they breathe.

At Ryerson University, scientists have been studying the levels of mercury in the air in Toronto because of concerns that after the chemical becomes airborne, it will settle into water supplies and food sources.

Compared to less populated areas, Dr Julia Lu and her research team found that mercury concentrations were higher in the city, spiking in June.

"We need to further our understanding of how cities contribute to the mercury problem," said Lu. "[Some] forms of mercury stay in the atmosphere for a shorter duration and therefore negatively impact local and regional areas."

People looking to protect themselves from airborne contaminants may benefit from supplements containing antioxidants like those found in broccoli.

Researchers at UCLA found that the chemical compounds found in the vegetable help the body fight respiratory inflammation caused by outdoor contaminants.