Effects of environmental factors on the longevous people in China.

Healthy longevity is associated with environmental conditions, but its significance is still unclear. In China, different age groups of old people may be influenced by different factors. For people aged 65 and above, their distribution may be more influenced by the economical factor, decreasing from east to west. However, for people aged 100 and above, they may be more influenced by the environmental factors. The number of centenarians per 100,000 is opposite to the percentage of people above 65, decreasing from west to east. Longevity index (LI%) and centenarity index (CI%) may be as index to evaluate the longevity level. The biggest LI% is in the south provinces of China, whereas the biggest CI% is in the northwestern provinces of China. The South China and Northwestern China are two longevity regions. The South China has some climatic preferences including near to the sea, having suitable mean year temperature, a large plenty of rainfall, higher relative humidity, which contribute to its relatively high longevity level. While the Northwestern China has the topographic and sunshine advantages, which help the residents there more probable to reach 100 years old. The results indicate that for old people, their distribution will be influenced by the environmental factor to some extent.