In Tai Wan, TNR was carried out in some districts. The Life Conservationist Association reports that the number of stray animals decreased from 13,281 to 9,515 (nearly 25%) during 2009 and 2010. This demonstrates the effectiveness of the TNR in controlling the stray cat population. Therefore, considering the environment, society, politics and animal welfare, TNR is the most effective and humane way to solve the problem of overcrowded stray cat population. First, from an environmental perspective, TNR helps improve public hygiene in Hong Kong. Most stray cats have the ability to catch rats and cockroaches. This reduces the number of parasites in the community. It also prevents the invasion of pests from other districts. As a result, public hygiene could be improved. Additionally, the Life Line Animal Organization reports that neutering cats could successfully reduce the problem of spraying and urine odor by 87 percent. The streets will be less smelly and the environment may be cleaner. Therefore, TNR could effectively solve the environmental problem caused by strays