Respiratory disease is the most common cause of mortality in children in underdeveloped economies and the commonest cause of morbidity in developed economies. Respiratory tract symptoms are particularly prevalent in young children and evidence for the relative contributions of potentially remediable environmental factors is emerging. The state of children’s respiratory health is determined by the interaction of many factors including potential stressors from their environment, patterns of exposure, individual vulnerability and genetics. Identifiable risk factors include infection, air pollution (indoors and outdoors), diet, lifestyle, social condition, occupation, and provision of medical care. They produce a multi-causal effect that has both short- and longer-term manifestations with implications for lifelong respiratory health. This effect varies with gender, developmental age and ethnicity.
This report provides a succint overview of the current state of knowledge with regard to the influence of the environment on the respiratory health of children, comprising the whole array of disorders and symptoms affecting the respiratory tract ranging from rhinitis and upper respiratory tract infections to asthma and pneumonia. The target population covers the period from fetus to young adult (up to 18 years of age) in order to reflect the whole range of age-specific conditions and unique periods of vulnerability dependent on growth and development. It aims to identify the gaps in knowledge and highlight the areas where policy action at Community level would have a significant impact on improving respiratory health in the EU.
: causes of death in children in Africa and South East Asia
Childhood respiratory illness is the commonest cause of morbidity in industrialised countries and, acute respiratory infections (ARI) are common causes of death and serious morbidity in young children in underdeveloped and emerging economies (Figure 1). Serious morbidity is less and the causative infective agents differ in developed economies such as those in the EU in that bacterial infections, including tuberculosis, are common in underdeveloped countries while viral infections explain most ARI in developed economies. In temperate European countries there is a marked seasonality of ARI with a significant rise in prevalence in the winter months falling to relatively low levels in the summer.
: Reports of respiratory syncitial virus (RSV) isolates 1995-2000
This pattern is evident for the respiratory syncytial virus (RSV) which is the commonest cause of the viral pneumonia labelled as “bronchiolitis” and which predominantly affects infants and very young children (Figure 2). Whereas serious morbidity and mortality from respiratory disease has fallen to low levels in developed economies, the total burden of respiratory disease remains high with a shift from life threatening ARI to an increased incidence of asthma and related atopic disease (rhinitis/hayfever and eczema).
The reasons for what has been termed the “asthma and atopy epidemic” are not yet entirely clear although several environmental risk factors have been proposed including a reduction in the overall burden of infectious disease – the so-called hygiene hypothesis [Strachan, 1989], dietary factors including low anti-oxidant intake [Seaton et al 1994; Fogarty & Britton 2000] and greater intake of processed fats [Helms 2001].
Whereas in the last decade increased exposure to allergens and particularly those within the internal environment, including the house dust mite, were considered to be major factors, more recent data do not support this association [Custovic et al 1998; Gotzsche et al 1998]. Prospective birth cohort studies are currently in progress in order to clarify the relative contribution of the putative risk factors [Lau et al 2000; Burrows et al 1995] and some of the major European cohorts are identified in chapter 5).