Lecture 5 : Environmental Factors (1) Overview

1. Lecture 5 : Environmental Factors (1) Overview • CLIMATE • WEATHER • AIR POLLUTION • RADIATION • PLANETARY INFLUENCES

2. Climate • Climatic variations may exert a significant influence in large countries (such as Russia, China or the USA), but are unlikely to explain regional inequalities in health in small countries like Ireland. • Seasonal variations are significant in many countries. Underdeveloped countries often have a summer mortality peak due to infectious diseases. Developed countries tend to have a winter peak.

3. Weather • There are a number of associations between specific diseases and weather conditions. • Mental unrest and some nervous disorders (e.g. epilepsy, suicides, insomnia) may be associated with electrical disturbances associated with cold fronts. • Anticyclonic conditions sometimes cause summer mortality ‘spikes’ associated with heat wave conditions. In winter they may be associated with air pollution episodes.

4. Weather Effects (Source: Howe, 1972)

5. Air Pollution (1) • Traditionally the main polutants were SO2 and smoke form factory and household fires. • Air pollution episodes were worst under anticyclonic conditions in the winter months. The cold conditions meant more fuel was burnt, whilst the absence of wind, plus a possible temperature inversion, meant the pollution was not dispersed. • It is possible to identify the major towns and cities from a map of air pollution in the UK. • In Dublin, coal fires tended to be more common in the west and north of the city. • These pollutants are now kept under reasonable control by the introduction of smokeless zones.

8. Air Pollution (2) Motor vehicle exhausts emit several pollutants: • Carbon monoxide (CO). Interferes with the oxygen carrying capacity of the blood. • Lead (Pb). Reduced following introduction of unleaded petrol. Causes brain damage to children. • Oxides of nitrogen (NOx). NO and NO2 result in respiratory problems at high concentrations. • Volatile Organic Compounds (VOCs). Combine in presence of UV light to produce secondary pollutants such as ozone (O3), PAN, PBN in a photochemical smog. • PM10s. Very small particles. Associated with heart attacks, respiratory diseases, and asthma.

9. Air Pollution (3) • Air pollution can trigger ‘episodes’ for people already suffering from cardiovascular disease, asthma or other respiratory diseases. However, it is not clear to what extent it causes these diseases. • Gatrell (2003) includes a figure which showing the relationship between mortality and selected pollutants in 6 US cities. Most pollutants show a strong relationship, but ozone is an exception.

11. Radiation • Ionising radiations may be man-made (e.g. nuclear power, X-rays), but most are naturally occurring. • Radon-222, a radioactive gas in the uranium series, can seep into houses where it may be breathed in. Further radiactive decay may result in the lungs being bombarded from the inside by radioactive emissions. Radon is second most important cause of lung cancer (after smoking). • Naturally occuring radiations are most common in areas with acidic igneus rocks such as granite. • Most non-ionising radiations, such as UV-B, originate from the Sun and are a cause of malignant melanoma – the most serious form of skin cancer. The depletion of the ozone layer in the upper atmosphere, which provides protection is a serious concern.

13. Planetary Influences • Some mental illnesses appear to be linked to cycles of the moon. • Sun spot activity is allegedly linked to increases in infectious diseases and heart diseases. • People born under the star sign of Pisces are more at risk of developing schizophrenia.