View - ResearchSpace@Auckland - The University of Auckland

2.1 Introduction
Chapter 2: Nitric oxide: pollutant to mediator
There are two lines of research, from quite disparate areas, that came together to make the
studies described in Chapters 6, 7 and, 8 possible. The first is the measurement of air
pollution, which has been increasingly important due to recognition that different pollutants
cause or contribute to human disease, including nitrogen oxides; and the second is the
increasing recognition of the importance of nitric oxide (NO) in biological systems in the last
25 years. I will examine the developments in both of these areas that led to the
commencement of the research described in this thesis.
2.2 Pollution. nitrogen oxides and disease
2.2.1 Concerns regarding pollution
There is now no doubt that episodes of air pollution have resulted in excess deaths. Concerns
with regard to pollution and its effects on health date back to early last century, although the
detrimental effects of poor air quality and poor housing have been recognised for far longer.
Indoor air pollution can be traced to some 200,000 years ago, when humans first moved to
colder climates necessitating the construction of shelters and use of indoor fires for cooking,
warmth and light. These mostly 'inside' fires likely resulted in an excess exposure to levels of
pollution as evidenced by the carbon soot found in prehistoric caves (Brims and Chauhan
2005). Severe outdoor air pollution episodes have been documented since the early 17ft
century but these became more frequent and more severe throughout the 19ft century. The
most definitive and well documented episodes were the great smogs that occurred in London,
United Kingdom, in 1948, 1952 and 1962, with the most severe occurring in December 1952
(Brims and Chauhan 2005). The smoke concentration at this time was 50 times above the
average level, and this rise in pollution was followed by an equally sharp rise in mortality
(Ministry of Health, UK 1954). An estimated human death toll of 4,000 occurred during this
period which was three times the expected mortality for that time of year. Most deaths were
among infants, the elderly and those with chronic respiratory disease (Anderson, ponce de
Leon et al. 1996).In addition, emergency hospital admissions tripled for respiratory disease,
and doubled for cardiovascular disease over the same period (Schwartz l99l). These led to
the Clean Air Act in 1956 and 1968 in the United Kingdom (UK), with further modifications
to the Act made in 1993.
49