Environmental medicine
An environment is the physical factors of surroundings including the land, waters,
atmosphere, climate, sound, odours, tastes, Biological factors of animals and plants and
social factor of aesthetics.
Environmental hazards can have both human and natural origins, and can involve low level
long term exposures or catastrophic events. They can cause direct harm or operate indirectly
via other agents such as our water and food sources.
Sustainability and diversity
Sustainability is the stewardship of good ambient so that future generations may have it too.
Diversity refers to respecting the right to exist of a wide range of other living beings.
Air and Soil
Practising environmental medicine
Our environment has potential to harm health. They can be subtle. Environmental medicine is
concerned with exposure and their effect on health. These exposures come from air, water,
soil, food, reacreation and play.
When practising, your patient will present with illness or injury that is environmentally related.
This needs time and though to go through with the patient. One of the most challenging
communication skill is to give clear measured counsel to patients about situations
where there are many uncertainties, including:
• Nature of exposure
• Severity of exposure
• Whether health effects are likely consequence of exposure
• Whether described health effects can be characterised as a single entity
If a patient presents you with health problem and postulates environmental cause, ALWAYS
consider a differential diagnosis. Environmental related conditions are relatively rare and
there can be misdiagnoses if you are too quick to accept.
While naming substances may be useful to classify or compare substances in abstract term in
a lecture setting, it will not be useful if it was actually present. This is because blabbing about
likely effect without telling the corresponding exposure level can be seriously misleading and
may cause hazard to masquerade as risk
Changing the dose of a substance will change the severity of effects or the probability
of their occurrence or both.
Our understanding of effects of substances is assisted by seeing similarities and patterns
when we compare substances, and by knowing the particular susceptibilities of target cells,
organs and body systems.
If people are exposed to substance in context of fear, then symptoms can relate to either the
substance or fear.
Limits of epidemiology
• Epidemiology is often a very weak probe of cause and effect.
• This happens because exposures are extremely hard to measure and are
multiple, it is hard to define the limits of a population of interest and cases tend
to be few and somewhat idiosyncratic
Normal Outdoor Atmosphere
The atmosphere has 5000 trillion tonnes of gas around the earth. Its depth exceeds 500km
but altitude of the exact upper limit is difficult to define since pressure decreases
exponentially from sea level to virtually zero in outer space
,The lower atmosphere consist of 78% nitrogen, 21% oxygen, nearly 1% argon, 0.04% carbon
dioxide plus water vapour (up to 0.7%) and other gases.
The atmosphere helps cushions temperature fluctuations on the surface of the Earth by
acting as ‘thermal blanket’ that makes the Earth habitable.
Lowest 16km of atmosphere is where local temperature, pressure, wind and precipitation
takes place. This is called the troposphere and in it the air temperature falls gradually
with increasing altitude.
Convection is upward floating of mass or pocket of air that is warmer and hence less
dense or conversely the sinking of cooler air. Convection is responsible for vertical
currents in the troposphere. A “thermal’ is a column of rising air caused by uneven heating of
the surface of the Earth.
When there is cloudless night and very still air, surface of ground becomes very cold. This
cools the air near the ground below temperature of air above and vertical convection ceases.
This is called temperature inversion, a natural phenomenon without upward movement of
air. All of the bad pollutants will stay at the bottom.
Humidity is the amount of water vapour in the air. After rain, the air becomes more saturated
with water vapour. Hotter air holds more moisture like how hotter water dissolve more sugar
Cold air moving sideways, being denser than warm air, tends to displace warm air upwards.
There the warm air cools and water vapour condenses around tiny dust particle to bring rain.
Clouds are a combination of tiny water droplets or ice crystals suspended in the atmosphere.
The temperature declines with altitude in the troposphere but increases in stratophere, then
declines in the mesosphere and increases again in the thermosphere (sort of W shaped
temperature gradient.
Partciulate air pollution is NOT the principle contributor to greenhouse effect but water vapour
and carbon dioxide tend to absorb terrestrial radiation.
Ozone
Ozone consist of three oxygen atom. It is a gas with low water solubility and a pungent smell.
Produced by high frequency UVC lights on ordinary oxygen molecules.
This production happens in the stratosphere (above troposphere) but also a result of lightning
or electric sparks. Due to strong oxidative effect, inhaling much ozone has potential to
generate alveolar inflammation that can extend to pulmonary edema.
Stratospheric ozone reduction has been observed particularly at polar regions where natural
production is least due to less intensive irradiation from the sun. Although high energy UVC
generates ozone, UVB converts ozone back to oxygen. When ozone is sparse, less UVB
is absorbed in the stratosphere and hence a higher proportion reaches the earth surface
and cause increased incidence of eye cataract and non-melanoma skin cancer in light
skinned individuals.
Outdoor air pollution
Important outdoor air pollution sources hre vehicle emissions and large scale fossil fuel
burning. Most Important air pollutants are particulates and gases. Gases such as NO2 and
SO2 can inflame the airway. In temperature inversion, pollutants can build in
concentration.
The engines of cars are hot enough to cause internal combustion and hence lead to NO
production that combines with oxygen in the air and form NO2. There is also unburnt
hydrocarbon vapour, along with NO that will take part in complex chemical reaction to
produce ozone (irritant gas). The mix of these irritant gases, together with tiny soot and dust
particles is know as photochemical smog.
, Some information about health effects of air pollution comes from epidemiological studies and
some from animal experiments. Epidemiology is hampered by confounders (smoking,
occupation, allergies), multiple coexisting exposures and exposures that are hard to measure.
During smog episodes or peak pollution, patients with asthma and COPD must reduce
outdoor activities. Days when visibility decrease below 10km, there is slight increase
admission for asthma and COPD.
N2O released from decomposition of fertilizers contributes to greenhouse effect though It is
NOT an irritant as it is used as an anesthetic gas (TREK 1 receptor activation opening K+
channels).
Airborne particles
Outdoor air contains tens of millions of particles per m3. These come from vehicle exhaust,
the weathering of rocks and loss of surface material from desserts, salt particles etc. Indoor
air contains skin flakes, fragments of clothing and furnishings, bacteria, fragments of mites,
sources of smoke such as grilling or tobacco smoking
Particle Size range Particle Size range
Sand ≥ 63 µm Bacteria 0.2 – 15 µm
Dust ≤ 63 µm Diesel & other smokes 0.01 – 1 µm
Pollen 10 – 100 µm Tobacco smoke 0.01 – 0.5 µm
Fungal spores 1 – 5 µm
Moisture absorbing (hygroscopic) dust high in the atmosphere seeds water vapour into
clouds and rain.
Particles with aerodynamic equivalent diameter <7um reach the alveoli and be engulfed by
macrophages
• Particles >10um tend to fall reasonably rapidly from air
• Usually particles that are <10um will be able to get to the trachea
• Particles <1um will have a low terminal velocity and mostly remain airborne to be
breathed out
Sooty particles will adsorb irritant gaseous molecules to their surface. When inhaled, a small
proportion of these particles ill contact the surfaces of airways and alveoli and may cause
inflammation.
The international agency for research on cancer classifies diesel engine exhaust as human
carcinogen. Many efforts are going into improving the design of diesel engines to reduce
emissions
La Trobe Valley Hazelwood open cut coal mine burnt for 6.5 weeks and covered Morwell will
plumes of smoke and ash. The particles dominating were those of most signifiance to health
with diameter of <2.5um. Other pollutants include CO and carcinogens benzoapyrene and
benzene.
Odour
Unwanted odours in neighbourhoods are quite common source of complaint to government
pollution authorities.
Presence of odour indicates airborne molecules stimulating olfactory nerve endings. The
emotional consequence of an odour is not so much the odour itself but what our brain
does with the stimulus. An odour can most powerfully draw out thoughts back to
pleasurable or nasty events or to the thought of loved ones or foes in our earlier lives.
If a person falls ill due to bad odour, whether directly to the odour or not, then if the odour
returns, it can trigger further symptoms like a conditioned reflex. The belief, instead of the
demonstrable effects of the odourous molecules, is what triggers symptoms. For some,
pleasant smells may also trigger symptoms.
An environment is the physical factors of surroundings including the land, waters,
atmosphere, climate, sound, odours, tastes, Biological factors of animals and plants and
social factor of aesthetics.
Environmental hazards can have both human and natural origins, and can involve low level
long term exposures or catastrophic events. They can cause direct harm or operate indirectly
via other agents such as our water and food sources.
Sustainability and diversity
Sustainability is the stewardship of good ambient so that future generations may have it too.
Diversity refers to respecting the right to exist of a wide range of other living beings.
Air and Soil
Practising environmental medicine
Our environment has potential to harm health. They can be subtle. Environmental medicine is
concerned with exposure and their effect on health. These exposures come from air, water,
soil, food, reacreation and play.
When practising, your patient will present with illness or injury that is environmentally related.
This needs time and though to go through with the patient. One of the most challenging
communication skill is to give clear measured counsel to patients about situations
where there are many uncertainties, including:
• Nature of exposure
• Severity of exposure
• Whether health effects are likely consequence of exposure
• Whether described health effects can be characterised as a single entity
If a patient presents you with health problem and postulates environmental cause, ALWAYS
consider a differential diagnosis. Environmental related conditions are relatively rare and
there can be misdiagnoses if you are too quick to accept.
While naming substances may be useful to classify or compare substances in abstract term in
a lecture setting, it will not be useful if it was actually present. This is because blabbing about
likely effect without telling the corresponding exposure level can be seriously misleading and
may cause hazard to masquerade as risk
Changing the dose of a substance will change the severity of effects or the probability
of their occurrence or both.
Our understanding of effects of substances is assisted by seeing similarities and patterns
when we compare substances, and by knowing the particular susceptibilities of target cells,
organs and body systems.
If people are exposed to substance in context of fear, then symptoms can relate to either the
substance or fear.
Limits of epidemiology
• Epidemiology is often a very weak probe of cause and effect.
• This happens because exposures are extremely hard to measure and are
multiple, it is hard to define the limits of a population of interest and cases tend
to be few and somewhat idiosyncratic
Normal Outdoor Atmosphere
The atmosphere has 5000 trillion tonnes of gas around the earth. Its depth exceeds 500km
but altitude of the exact upper limit is difficult to define since pressure decreases
exponentially from sea level to virtually zero in outer space
,The lower atmosphere consist of 78% nitrogen, 21% oxygen, nearly 1% argon, 0.04% carbon
dioxide plus water vapour (up to 0.7%) and other gases.
The atmosphere helps cushions temperature fluctuations on the surface of the Earth by
acting as ‘thermal blanket’ that makes the Earth habitable.
Lowest 16km of atmosphere is where local temperature, pressure, wind and precipitation
takes place. This is called the troposphere and in it the air temperature falls gradually
with increasing altitude.
Convection is upward floating of mass or pocket of air that is warmer and hence less
dense or conversely the sinking of cooler air. Convection is responsible for vertical
currents in the troposphere. A “thermal’ is a column of rising air caused by uneven heating of
the surface of the Earth.
When there is cloudless night and very still air, surface of ground becomes very cold. This
cools the air near the ground below temperature of air above and vertical convection ceases.
This is called temperature inversion, a natural phenomenon without upward movement of
air. All of the bad pollutants will stay at the bottom.
Humidity is the amount of water vapour in the air. After rain, the air becomes more saturated
with water vapour. Hotter air holds more moisture like how hotter water dissolve more sugar
Cold air moving sideways, being denser than warm air, tends to displace warm air upwards.
There the warm air cools and water vapour condenses around tiny dust particle to bring rain.
Clouds are a combination of tiny water droplets or ice crystals suspended in the atmosphere.
The temperature declines with altitude in the troposphere but increases in stratophere, then
declines in the mesosphere and increases again in the thermosphere (sort of W shaped
temperature gradient.
Partciulate air pollution is NOT the principle contributor to greenhouse effect but water vapour
and carbon dioxide tend to absorb terrestrial radiation.
Ozone
Ozone consist of three oxygen atom. It is a gas with low water solubility and a pungent smell.
Produced by high frequency UVC lights on ordinary oxygen molecules.
This production happens in the stratosphere (above troposphere) but also a result of lightning
or electric sparks. Due to strong oxidative effect, inhaling much ozone has potential to
generate alveolar inflammation that can extend to pulmonary edema.
Stratospheric ozone reduction has been observed particularly at polar regions where natural
production is least due to less intensive irradiation from the sun. Although high energy UVC
generates ozone, UVB converts ozone back to oxygen. When ozone is sparse, less UVB
is absorbed in the stratosphere and hence a higher proportion reaches the earth surface
and cause increased incidence of eye cataract and non-melanoma skin cancer in light
skinned individuals.
Outdoor air pollution
Important outdoor air pollution sources hre vehicle emissions and large scale fossil fuel
burning. Most Important air pollutants are particulates and gases. Gases such as NO2 and
SO2 can inflame the airway. In temperature inversion, pollutants can build in
concentration.
The engines of cars are hot enough to cause internal combustion and hence lead to NO
production that combines with oxygen in the air and form NO2. There is also unburnt
hydrocarbon vapour, along with NO that will take part in complex chemical reaction to
produce ozone (irritant gas). The mix of these irritant gases, together with tiny soot and dust
particles is know as photochemical smog.
, Some information about health effects of air pollution comes from epidemiological studies and
some from animal experiments. Epidemiology is hampered by confounders (smoking,
occupation, allergies), multiple coexisting exposures and exposures that are hard to measure.
During smog episodes or peak pollution, patients with asthma and COPD must reduce
outdoor activities. Days when visibility decrease below 10km, there is slight increase
admission for asthma and COPD.
N2O released from decomposition of fertilizers contributes to greenhouse effect though It is
NOT an irritant as it is used as an anesthetic gas (TREK 1 receptor activation opening K+
channels).
Airborne particles
Outdoor air contains tens of millions of particles per m3. These come from vehicle exhaust,
the weathering of rocks and loss of surface material from desserts, salt particles etc. Indoor
air contains skin flakes, fragments of clothing and furnishings, bacteria, fragments of mites,
sources of smoke such as grilling or tobacco smoking
Particle Size range Particle Size range
Sand ≥ 63 µm Bacteria 0.2 – 15 µm
Dust ≤ 63 µm Diesel & other smokes 0.01 – 1 µm
Pollen 10 – 100 µm Tobacco smoke 0.01 – 0.5 µm
Fungal spores 1 – 5 µm
Moisture absorbing (hygroscopic) dust high in the atmosphere seeds water vapour into
clouds and rain.
Particles with aerodynamic equivalent diameter <7um reach the alveoli and be engulfed by
macrophages
• Particles >10um tend to fall reasonably rapidly from air
• Usually particles that are <10um will be able to get to the trachea
• Particles <1um will have a low terminal velocity and mostly remain airborne to be
breathed out
Sooty particles will adsorb irritant gaseous molecules to their surface. When inhaled, a small
proportion of these particles ill contact the surfaces of airways and alveoli and may cause
inflammation.
The international agency for research on cancer classifies diesel engine exhaust as human
carcinogen. Many efforts are going into improving the design of diesel engines to reduce
emissions
La Trobe Valley Hazelwood open cut coal mine burnt for 6.5 weeks and covered Morwell will
plumes of smoke and ash. The particles dominating were those of most signifiance to health
with diameter of <2.5um. Other pollutants include CO and carcinogens benzoapyrene and
benzene.
Odour
Unwanted odours in neighbourhoods are quite common source of complaint to government
pollution authorities.
Presence of odour indicates airborne molecules stimulating olfactory nerve endings. The
emotional consequence of an odour is not so much the odour itself but what our brain
does with the stimulus. An odour can most powerfully draw out thoughts back to
pleasurable or nasty events or to the thought of loved ones or foes in our earlier lives.
If a person falls ill due to bad odour, whether directly to the odour or not, then if the odour
returns, it can trigger further symptoms like a conditioned reflex. The belief, instead of the
demonstrable effects of the odourous molecules, is what triggers symptoms. For some,
pleasant smells may also trigger symptoms.
