Killer smog: Even small amounts of air pollution linked to risk of early death, study finds.........Smog isn't just annoying, it's also deadly: Exposure to even small amounts of toxic air pollutants is linked to increased cardiovascular and respiratory death rates, according to a new international study.

 The study, published Wednesday in the New England Journal of Medicine, is the largest ever undertaken to investigate the short-term impacts of air pollution on death. It was conducted over 30 years in 652 cities in 24 countries.

 The study looked at tiny particles of pollution known as particulate matter (PM). 

 "The smaller the airborne particles, the more easily they can penetrate deep into the lungs and absorb more toxic components, causing death,” said study lead author Yuming Guo from Monash University's School of Public Health in Melbourne, Australia. 

 Guo said there is no threshold for the association between particulate matter and mortality: "Even low levels of air pollution can increase the risk of death," he said.