The relevant features of the physical environment that are particularly important to urban areas include access to safe drinking water, sanitation, drainage, and garbage collection; also important are air and noise pollution and the built environment.
30 Especially important from a health perspective are the pathogens and vectors associated with high levels of infectious and parasitic diseases, including diarrheal diseases, intestinal parasites, and “water-washed” diseases. Providing access to safe water, garbage removal, and sanitation in the late 19th and early 20th centuries created the conditions for the dramatic reductions in mortality from infectious diseases in developed nations;
31 now cities in developing nations face these same challenges.
15
,
32
–
34 Hazardous waste landfill sites are often located in or near urban areas or, in the case of slums in developing countries, may be the land on which housing is built; these landfills may be associated with risks of low birth weight, birth defects, infectious diseases, and cancers.
35 In terms of air pollution, the developed and developing worlds differ in terms of types and concentrations of pollutants, especially with differences in indoor pollution.
36 Environmental particulate matter has been associated with cardiovascular death and asthma.
37
,
38 Noise exposure, a common urban problem, may be associated with hearing impairment, hypertension, and ischemic heart disease.
39 The built environment also influences health.
40
,
41 Inadequate, overcrowded, or deteriorating housing or informal settlements, especially where tenure is insecure (i.e., makeshift, tenements, or cheap boarding houses), is associated with injuries, respiratory problems, infectious diseases, and mental health problems.
21
,
22
,
24
,
42 Poor transportation inhibits access to employment and health services; poor work conditions lead to injuries. Another determinant of health is access to and sufficient quantities of safe and quality food.
18 Another aspect of the physical environment is climate and geography, and the vulnerability to natural disasters including cyclones, floods, earthquakes, landslides, fires, and industrial accidents.
6 This topic is further addressed in another paper in this issue.
43