Asthma is a serious chronic disorder of the lungs. During an asthma attack the airways narrow causing breathlessness, wheezing, coughing and a tight feeling in the chest.
The severity and frequency of these attacks vary from person to person. According to the WHO 300 million people around the world suffer from asthma, a figure predicted to grow to 400-450 million people by 2025.
Asthma is a complex disease whose development is known to have genetic and environmental components. The environmental risk factors include exposure to allergens such as domestic mites, cockroach faeces, fungi, moulds, pollen, infection, tobacco smoke and chemicals.
Although the causes of asthma are not fully understood, the recent increase in prevalence of asthma cannot be explained by genetic factors alone. Asthma is increasingly occurring in individuals without a family history of the disease, whilst the rapid increase in incidence has occurred faster than that associated with inherited changes, which take place over several generations.
Figure 1. World map of the prevalence of clinical asthma Masoli M, Fabian D, Holt S, Beasley R. Global Burden of Asthma, 2004). Enlarge the picture
Over the last three decades indoor and outdoor air quality has changed dramatically. New chemical products have been introduced into household goods and building materials, whilst ozone and fine particle pollution from diesel engine exhaust remain an ongoing or increasing problem. Consequently, it may be that environmental factors are playing an increasingly important role in disease development. This in turn may explain why increasing asthma rates have been accompanied by the adoption of more urbanised and western lifestyles.
Moreover, recent research suggests that foetus or early life exposure to chemicals can result in infants becoming sensitized to environmental contaminants, leading to immune system changes which can in turn lead to the development of asthma.
The economic burden of asthma is considerable. According to the ERS White Book, in Europe, the total cost of asthma amounts to Euros 17.7bn per year. Lost productivity resulting from poor asthma controls is estimated at Euros 9.8bn per year.
Figure 2. Cost of Care for Asthma in Europe, European Lung Foundation Enlarge the picture
Asthma is a major public health burden. Although pharmacologic intervention to treat established asthma is very effective, mounting evidence implicating environmental factors in asthma development suggests that tackling rising incidence rates will require a focus on primary prevention measures, to prevent the disease’s development by reducing exposure to risk factors.