Urbanization comes with pros and cons for city dwellers, although the scene is far more worrying for wildlife. A new study by Lund University in Sweden says that not just urban people suffer from light, noise and air pollution, as well as the limited availability of natural food sources, but so do animals, especially birds. Biology researchers at Lund University found that living in an urban environment shortens the longevity of great tits, a passerine bird species. "The urban environment imposes a challenge to developing birds, with potentially irreversible effects on lifespan," the study said, as published in Biology Letters.The team suggested that great tit chicks raised in urban environments had shorter telomeres (a suggested bio-marker for longevity) and the telomeres of city-raised chicks were shorter than those of chicks raised in the countryside. Science magazine reported that increased stress because of city pollution can cause DNA damage, which blamed for the rapid cellular ageing seen in great tit chicks.Air pollution continues to threaten the health of living beings around the world, especially in China, Iran and India. Although birds and mammals are not directly affected by water acidification, they are indirectly affected by changes in the quantity and quality of their food resources. Birds can be affected by the fumes from coal power production, which can damage their respiratory systems. They also are indirectly affected by air pollution. Mercury accumulates as it moves through the food chain, becoming very harmful to predatory birds.