Hygienic living conditions are critical to preventing the spread of potentially fatal diseases. Simple everyday practices, such as proper waste disposal, adequate sanitation and the use of clean water, help improve health outcomes. However, not everyone has access to these basic living conditions, a circumstance that often depends on one's economic situation. This disparity may contribute to a greater likelihood that some people will have a shorter life expectancy.
Longevity has increased over the past century thanks to medical advances and lifestyle improvements. Not only has average life expectancy increased since 1900, but a greater number of people are living to older ages, due in part to the sharp decline in the high infant mortality rate that characterized the early 20th century.
