Lecture 5 : Environmental Factors 1 Overview

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Lecture 5 Environmental Factors (1) Overview

• CLIMATE
• WEATHER
• AIR POLLUTION
• RADIATION
• PLANETARY INFLUENCES

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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.

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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.

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Weather Effects
(Source Howe, 1972)
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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.

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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.

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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.

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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.

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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.