Air Pollution and Health

1
Air Pollution and Health

• specific sections of the public most affected by
  air pollution
• diseases of the cardiorespiratory system -
  asthmatics and smokers far more likely to be
  affected

2
Air Pollution and Health
3
Air Pollution and Health

• Pollutants act on surfaces of respiratory system
  chronic respiratory and cardiovascular disease
  
• alter O2 exchange in lungs, and transport in
  blood
• Irritant pollutants long term damage to eyes,
  nose, throat and wet surfaces of body
• H2SO4 particles irritate mucous membranes and
  cause bronchial constriction

4
Air Pollution and Health

• gaseous effects more acute than chronic (as
  opposed to the particulate pollutants)
• SO2, O3 and NO2 are pulmonary irritants, may
  cause congestion, oedema and haemorrhage
• NO, H2S and CO are asphyxiant gases
• organic gas pollutants e.g. acrolein (1-propenal)
  as well as those gaseous pollutants mentioned
  above produce eye irritation

5
Synergism

• Interaction between pollutants may be additive,
  synergistic, or antagonistic
• Synergistic effects are those where the sum of
  the effects of two or more pollutants is less
  than the combined effect i.e. 1 1 3
• The great majority of pollutant effects are
  additive.

6
How are we affected?

• three main routes by which pollutants enter the
  body
• absorption through the skin
• ingestion, and
• inhalation

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Air Pollution and Health
8
Carbon Monoxide

• preferentially and irreversibly binds to
  haemoglobin in blood forming carboxyhaemoglobin
• reduces blood's capacity to carry O2 as CO has a
  higher affinity (200X greater) for haemoglobin
  than O2
• medical evidence suggests that continued exposure
  to low levels of CO may cause nervous disorders
  and be a factor in the cause of heart disease

9
Carbon Monoxide

• CO in urban environments usually only a fraction
  of those levels that cause asphyxiation
• low level effects behavioural changes,
  decreased time interval discrimination,
  impairment of brightness discrimination,
  increased reaction time to visual stimuli, and
  lowered performance in driving simulations
• may be the cause of many motor vehicle accidents
  in peak hour traffic of cities where peak hour CO
  levels may rise above 50ppm

10
Carbon Monoxide

• For cigarette smokers, CO exposures far more
  significant (an average 3 8 carboxyhaemoglobin
  saturation) than those experienced under urban
  ambient conditions

11
Sulfur Compounds

• Sulfur Dioxide and Particulates
• Analysis of the effects of SO2 complicated by
  association with particulate pollutants direct
  effects of each individual pollutant are
  difficult to separate.
• often produced by a common source, (combustion of
  coal), hence high SO2 levels often associated
  with high particulate matter levels - forming
  sulfate aerosols
• aerosols just the right size to be retained in
  the lungs so cause maximum physiological damage

12
Sulfur Compounds

• Sulfur Dioxide
• primary effect on respiratory tract, producing
  irritation and difficulty breathing
• affects most strongly people with respiratory
  problems
• children known to suffer increased frequency of
  infection upon prolonged exposure to SO2
• long term effects of exposure not well understood

13
Sulfur Compounds
14
Sulfur Compounds

• Sulfur Dioxide
• London smog of 1952 averaged about 4000-5000?g/m3
  
• Street levels in Wollongong in the late 1970s
  recorded values of 2250?g/m3 due to smelting
  operations
• water solubility - SO2 almost entirely removed
  in the mouth, throat, and nose through normal
  breathing
• lt 1 of inspired SO2 reaches lung tissue
  (alveoli)

15
Sulfur Compounds

• Sulfur Dioxide
• principal effect of SO2 exposure is to alter the
  mechanical function of the upper airway
• SO2 exposure at low levels (0.25 and 0.5ppm)
  produce acute bronchoconstriction on inhalation
• likely that health effects of SO2 are due to the
  highly irritant effects of sulfate aerosols, such
  as sulfuric acid, which are produced from SO2

16
Nitrogen Compounds

• Nitrogen Oxides
• NO not health threat but is converted to NO2
• NO2 exposure at low levels (0.5ppm) destroy cilia
  and obstruct respiration
• NO2 at 5ppm minor respiratory problems 100ppm
  non-fatal inflammation higher levels fatal

17
Hydrocarbon Compounds

• Hydrocarbons
• Most H/Cs relatively nontoxic at the ambient
  levels found in normal atmospheres
• Form photochemical smog very deleterious to
  health - reduce visibility, have unpleasant
  odours and cause skin and eye irritation at
  higher levels - some carcinogenic, benzoapyrene
  
• H/C air quality standards not based on health
  effects, but an attempt to reduce photochemical
  smog

18
Ozone and Photochemical Smog

• Ozone
• Ozone the most toxic pollutant regulated under
  ambient air quality standards
• may cause significant physiological and
  pathological changes in animals and humans at
  concs within range measured in polluted ambient
  environments
• The ambient air quality standard for O3 is
  0.12ppm (235?g/m3) averaged over 1 hour

19
Ozone and Photochemical Smog

• Ozone
• O3 may cause significant lung function changes
  even with exposures in the 0.10-0.40ppm range of
  for 1-2 hours
• Exposure to O3 levels above 0.12ppm, may lead to
  a variety of symptoms including throat dryness,
  chest tightness, coughing, pain, shortness of
  breath, lassitude, malaise, headache, and nausea
• may inhibit immune system's ability to defend the
  body against infection

20
Particulate Matter

• exhibits toxic effects due to direct irritant
  action of particles (such as H2SO4) and
  substances readily adsorbed to the large surface
  area of small particles
• concentration of adsorbed substances may be
  considerably greater than in ambient atmosphere
• adsorbed substances of particular concern include
  SOx, PAH, and heavy metals e.g. Pb, Cd, Zn and Hg

21
Particulate Matter

• Retention
• health consequences depend on ability to
  penetrate respiratory defence mechanisms
• remove inhaled particles in excess of 10?m, but
  particles smaller than can enter inhalable
  particles
• Particles lt 2.5?m respirable, enter pulmonary
  tissue

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Particulate Matter

• Retention

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Particulate Matter

• Retention
• deposition is slightly higher in smokers and
  greatly increased in individuals with lung
  disease
• retention varies greatly among the different
  regions of the respiratory tract
• ciliated airways of the nose and upper
  tracheobronchial zone, clearance in healthy
  individuals is achieved lt1 day

24
Particulate Matter

• Retention
• deeper in the lungs the time required for
  clearance greatly increases - 2 weeks to months

25
Particulate Matter

• Lead
• Atmospheric lead normally a chronic cumulative
  poison, mostly affecting the central nervous
  system, blood kidney
• at highest concentrations in particles of 0.2?m
  or less, which increases its access to animals by
  allowing access to the deep lung tissue
• lead crosses the placenta, resulting in high lead
  levels in the foetus, which may lead to mental
  retardation - blood lead much higher in smokers

26
Particulate Matter

• Asbestos
• inhalation of the fibres causes the lung disease
  asbestosis characterised by scarring of the
  lower lungs and lowered breathing function
• Some forms of asbestos are responsible for
  causing lung cancer and mesothelioma (cancer of
  the lining of the body cavity)
• Asbestos fibres are chronic toxins with very long
  latency periods - 1 fibre can kill eventually

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Effects on Plants

• Plants often the first to show damage associated
  with increased ambient levels of air pollution
• effects of SO2, HCl and HF reported as early as
  the middle of the 19th century
• most severe damage associated with high levels of
  SO2 and heavy metal particulates associated with
  mining and smelting

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Effects on Plants

• visible effects involve changes in leaf structure
  such as chlorophyll destruction (chlorosis),
  tissue death (necrosis) and pigment formation
• subtle effects include inhibition of growth and
  lowered photosynthesis

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Effects on Plants

• Sulfur Dioxide
• harmful to certain plants at levels below 1ppm,
  causing tissue damage and destruction of
  chlorophyll
• enters plant tissues through stomates where it
  comes into contact with the spongy mesophyll
  cells of the leaf causing tissue collapse
• injury extends from the bottom to the top of the
  leaf and is visible on both surfaces - alfalfa
  most affected injury at 1ppm for 1 hour

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Effects on Plants

• Sulfur Dioxide

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Effects on Plants

• Ozone
• also enters the leaf through the stomates
• symptoms of acute injury are visible on the upper
  leaf surface - younger plants more sensitive and
  older plants more resistant
• most common O3-induced symptom patterns observed
  on dicots are upper surface flecks and some
  bronzing

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Effects on Plants

• Ozone

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Effects on Plants

• Ozone

34
Effects on Plants

• Ozone
• sensitivity varies from species to species and
  from variety to variety within species
• more toxic to plants than SO2. Symptoms may be
  observed on sensitive plants from exposures of as
  little as 0.10 - 0.30ppm for a few hours
• estimated to be the cause of over 90 of all
  plant injury due to air pollution in North
  America

35
Effects on Plants

• Peroxyacyl Nitrate (PAN)
• causes glazing/browning appearance on the lower
  surface of the leaf
• PAN injury often appears as bands at the apex of
  the youngest sensitive leaf, the middle of an
  intermediate-aged leaf and the base of the oldest
  sensitive leaf
• Young, rapidly developing leaves on young rapidly
  growing plants are most sensitive to PAN

36
Effects on Plants

• PAN

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Effects on Plants

• Fluoride
• substantial effects on growing plant tissue
• Injury from gaseous HF through the stomates or
  from soluble particulate fluorides absorbed
  through the leaves and/or roots
• fluorides enter veins and are transported to leaf
  margins and/or the leaf tip, where they
  accumulate - appears as tip burn

38
Effects on Plants

• Fluoride

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Effects on Plants

• Particulates
• Direct effects such as those for cement kiln dust
  include a variety of plant responses, such as
• reduction in yield and growth without visible
  injury,
• increase in disease incidence,
• severe injury to leaf cells,
• suppression of photosynthesis, and
• death of trees

40
Effects on Buildings

• soiling building surfaces, clothing and other
  articles
• Most important are effects on metals, carbonate
  building stones, paints, textiles, fabric dyes,
  rubber, leather, and paper
• Physical damage from abrasive effect of
  wind-driven particulate matter - chemical
  reactions when pollutants and materials make
  direct contact