million scrap tires. Thirty-eight states have laws that ban whole tires being deposited in landfills. Many of these discarded tires end up illegally dumped on public lands. Tires can become a breeding ground for insect vectors which can transmit disease to humans. Mosquitoes, which breed in stagnant water, can transmit West Nile virus and malaria. Rodents nest in accumulated tires and can transmit diseases such as Hantavirus. When tires are burned, they can smolder for long periods of time, emitting hundreds of chemical compounds that pollute the air causing respiratory illnesses. Additionally the residue left behind can harm the soil and leach into groundwater. Visual pollution is a major effect of litter. Open containers such as paper cups, cardboard food packets, plastic drink bottles and aluminum drinks cans get filled up with rainwater, providing breeding locations for mosquitoes. In addition, a spark or a lightning flash can start a fire if it strikes litter such as a paper bag or cardboard box. Litter can be hazardous to health. Debris falling from vehicles is an increasing cause of automobile accidents. Discarded dangerous goods, chemicals, tires, sharps waste and pathogens resulting from litter can cause accidental harm to humans. Litter also carries substantial cost to the economy. Cleaning up litter in the US costs hundreds of dollars per ton, about ten times more than the cost of trash disposal, with a cost totaling about $11 billion per year. Effects on wildlife Animals may get trapped or poisoned with litter in their habitats. Cigarette butts and filters are a threat to wildlife and have been found in the stomachs of fish, birds and whales, who have mistaken them for food. Also, animals can get trapped in the rubbish and be in serious discomfort. For example, the plastic used to hold beverage cans together can get wrapped around animals' necks and cause them to suffocate as they grow. Other instances where animals could be harmed by litter include broken glass lacerating the paws of dogs, cats, and other small mammals. Other effects Organic litter in large amounts can cause water pollution and lead to algal blooms. Cigarettes could also start fires if they are not put out and then discarded in the environment. Extent Litter is an environmental concern in many countries around the world. While countries in the developing world lack the resources to deal with the issue, consumer based economies in the