Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity (WHO, 1948). Health effects are the primary reason to improve air quality. Health effects of air pollution occur both where people live and work.
The health impacts of air pollutants are numerous and varied and can become manifest in any compartment of the human body. Compartments affected include the respiratory system, immune system, skin and mucous tissues, sensory system, central and peripheral nervous system, and the cardiovascular system.
Health effects of air pollution on the respiratory system include acute and chronic changes in pulmonary function, increased incidence and prevalence of respiratory symptoms, sensitisation of airways to allergens, and exacerbation of respiratory infections such as rhinitis, sinusivitis, pneumonia, alveolitis, and legionnaires' disease. Principal agents for these health effects are the combustion products sulphur dioxide (SO2), nitrogen dixoide (NO2), particulate matter (PM10), and carbon monoxide (CO). In addition, indoor air pollutants—fine PM from environmental tobacco smoke (ETS), formaldehyde, and infectious organisms—can also act as important agents.
Health effects of air pollution on immune system allergies manifest themselves in exacerbation of allergic asthma, allergic rhino-conjunctivitis, extrinsic allergic alveolitis/hypersensitivity pneumonitis, and can produce permanent lung damage in sensitised individuals including pulmonary insufficiency. Principal agents are known to be outdoor allergens and indoor air agents such as house mite dust, cockroaches, organisms living in the pelt of pets, insects, and moulds in high humidity environments.
Multi-centre studies have shown different spatial patterns of allergic disease (e.g., asthma, rhinitis, and eczema) as well as allergic hyper-sensitisation. These variations cannot be reconciled by geographical differences in allergen exposure since the major aeroallergens are widespread. Pollens can trigger an allergic response in the airways of susceptible asthmatics, causing inflammation and consequent narrowing. At high concentrations air pollutants can enhance the effect of some pollens. Air pollution may also affect the concentration of pollens (EP, 2010).
Health effects of air pollution on the skin and on mucous tissues (eyes, nose, throat) are mostly irritating effects. Primary sensory irritations include dry—sore—throat, tingling sensation of nose, and watering and painful eyes. Secondary irritation is characterised by oedema and inflammation of the skin and mucous membranes up to irreversible changes in these organs. Principal agents include volatile organic compounds, formaldehyde and other aldehydes (e.g. acetaldehyde, acrolein) and ETS.
Sensory effects of air pollution include nuisance and annoyance reactions caused by perception of air pollutants through sensory organs. VOCs, formaldehyde and ETS can act as principal agents. Effects of air pollution on the central nervous system manifest themselves in damage of the nerve cells, either toxic or hypoxic/anoxic. Principal agents are VOCs (acetone, benzene, toluene, formaldehyde), CO and pesticides.
In infants and young children, neuro-physiological changes caused by Pb can result in developmental retardation and irreversible deficiencies. Effects of air pollution on the cardiovascular system develop through reduced oxygenation and result in increased incidence and prevalence of cardiovascular diseases, myocardial infarction, and consequent increase in mortality caused by cardiovascular diseases. Principal agents are CO, PM, and ETS. Carcinogenic effects of air pollution are associated with lung cancer, skin cancer, and leukaemia. Principal agents for lung cancer have been identified as arsenic, asbestos fibres, chromium, nickel, cadmium, polycyclic aromatic hydrocarbons (PAH), trichloroethylene, ETS, and radon. Benzene is known to produce leukaemia, and ultraviolet radiation is a causative agent of skin cancer.
A difficult and largely unresolved question is that of synergism among the different carcinogenic compounds and between carcinogenic and non-carcinogenic agents. The health impacts of lead are especially serious in children because lead affects the body during the crucial development. Children are known to develop learning disabilities and intelligence quotients decrease.
EP 2010 Air Pollution and Health. Environmental Protection UK, Brighton. Website: http://www.environmental-protection.org.uk/air-quality-and-climate/air-quality/air-pollution-and-health/.
Schwela 2009 Air Quality Management. Module 5a. Sustainable Transport: A Sourcebook for Policy-makers in Developing Cities – revised October 2009. Gtz, Transport Policy Advisory Services, Eschborn, Germany.
WHO 1948 Preamble to the Constitution of the World Health Organization as adopted by the International Health Conference, New York, 19-22 June, 1946; signed on 22 July 1946 by the representatives of 61 States (Official Records of the World Health Organization, no. 2, p. 100) and entered into force on 7 April 1948. World Health Organization, Geneva. Website: http://www.who.int/about/definition/en/print.html/