A 20-year study of residents of a Cairo suburb shows that the tiny particles in pollution air could lead to three times as many long-term health problems as was previously thought. A connection between the number of particles in the air health is suggested by Dr Razia of Cairo University. He and his colleagues collected data of tiny particles, those less than 2.5 microns in diameter. increased, so did the risk of dying from health problems such as heart attacks and lung cancer.