health especially of the poor,<sup>23</sup> the volume of (relatively) clean water<sup>24</sup> and waste disposal services are the first and strongest line of defense against several of the principal infectious diseases including diarrhea and malaria. Such infrastructure is a public good which affects the urban population and reduces health inequality (Soares 2007). Five childhood conditions (diarrhea, respiratory infections,<sup>25</sup> malaria, measles, and perinatal conditions) that can be reduced through preventive measures or treated through antibiotics, other antimicrobials and ORT are responsible for 21% of all deaths in lowand middle-income countries, while these account for only 1% of deaths in high-income countries (Bloom and Canning 2003).<sup>26</sup> The incidence of diarrhea among children in low income countries has changed little over the past decade (3.5 episodes per child per year), although oral rehydration therapy (ORT) has reduced mortality. G-I problems also affect the ability of children to absorb nutrients and make them more prone to chronic diseases later in life.

Infrastructure to supply the amount of water needed per individual and remove waste, which is the basis for a healthy city, requires major initial capital expenditure and continuing subsequent investment to maintain,<sup>27</sup> expand and upgrade the facilities. Thus the capital outlay is a fundamental consideration and an adequate infrastructure only becomes affordable once urban incomes have crossed a certain threshold.<sup>28</sup> The level of 23 Landers (1993) ascribes the easing of the extremely high mortality rates in London towards the close of the eighteenth century to the gradual improvement in housing conditions as a result of increased construction, the greater availability of cotton clothing which permitted frequent washing and killed lice, and possibly, the spread of inoculation. These three factors might have lessened the mortality from typhus, typhoid, and smallpox. The incidence of pneumonia among children is partly the result of indoor air pollution linked to substandard housing and use of biomass fuels.

24 Specter (2006) vividly describes the predicament of the poor in Delhi and in Chennai (India) where water is scarce. All inhabitants are affected but the poor most acutely. Slum dwellers in New Delhi spend more on (substandard) water than households with water supply connections. And Chennai residents often carry pails with them in the hope that they might chance upon clean water.

25 Pneumonia kills 2 million children under the age of 5 years annually (Wardlaw and others 2006).

26 Almost two million children die annually from diarrhea worldwide. For close to 90% of these, diarrhea is caused by lack of access to an adequate quantity of water and to effective sanitation (Cairncross and Valdmanis 2006; Kolsky and others 2005). Provision of basic sanitary facilities can reduce child mortality by 30% or more, with the provision of flush toilets having larger impact than pit latrines. A cost of such deficiencies in water and sanitation infrastructure is estimated as $170 billion ($23.5 billion in Sub-Saharan Africa, $29 billion in Latin America, and $34 billion for South Asia and $66 billion for East Asia) (UNDP 2006).

> 27 Maintenance usually requires expenditures equal to 7-10% of the initial capital costs of the facilities (Cairncross and Valdmanis 2006).

28 Szreter (2004) writes that urban life expectancies in Britain dipped below the national average in the 1830s and 1840s and did not start to rise above the national average until the 1870s even though per capita 12