There is also evidence that urban environmental factors associated with lower-income settings can aggravate, and perhaps even initiate, childhood asthma. Infant and child death in poor settlements is often not simply the result of a discrete disease but the outcome of a series of health problems. This typically involves an interplay of malnutrition, a variety of infectious diseases, and, possibly, exposure to chemical pollutants. Lack of health care increases vulnerability. Social factors, too, can be important in increasing the health risks that urban children face.
Adolescents seem to be particularly affected by inadequate urban social environments.
Data from some cities in North and South America suggest striking, age-specific problems with homicides among young men and boys. Urban women also face increased health risks, largely because of their social and economic roles, which expose them to greater numbers of environmental hazards. Women are usually responsible for taking care of sick children, increasing their direct exposure to disease-causing organisms. As the household food preparer, urban women in the developing world are often exposed to very high levels of smoke from cookstoves, which also put them at risk of receiving burns. Physiological factors also play a part in making women's health more vulnerable.