Final answer:
Low life expectancy in some countries is greatly affected by factors such as a lack of access to clean water, sanitation, healthcare, and high rates of infectious diseases and infant mortality.
Step-by-step explanation:
A big factor involved in low life expectancy for some countries is the overall quality of health factors and access to essential resources. In low-income countries, many factors contribute to low life expectancy, including infectious diseases, high infant mortality rates, a scarcity of medical personnel, and inadequate water and sewer systems. These conditions lead to high rates of infant mortality and lower average life spans compared to high-income countries. Adding to these, issues such as undernutrition, illiteracy, lack of safe drinking water, and poor healthcare infrastructure further lower the life expectancy. Additionally, broader socio-economic conditions like poverty, lack of education, violence, war, and weak healthcare systems are major contributors that negatively affect life expectancy.