Environmental Health
Mandatory readings on BB = highly recommended to study.
Evaluation:
• Written exam
• Open questions
1. Environmental health and the burden of disease
1.1 Context: health, public health and environmental health
1.1.1 What is health?
• WHO (1948 – constitution): “Health is a state of complete physical, mental and social well-being and
not merely the absence of disease or infirmity”
o It’s not an easy concept: when the WHO was founded, they needed to write a definition of
health. It goes a little beyond the absence of disease, it’s about wellbeing.
There were models about how to determine health. This is the
model of Dahlgren and Whitehead (1991):
• In the center are the individuals: what determines
health for individuals are sex, age, constitutional
factors…
• Orange: individual lifestyle factors. Examples: physical
activities, smoking…
• Yellow: social and community networks. Examples:
friends, family, relationships… They can also determine
what our lifestyles are. Friends have a big impact if you
start smoking or not.
• Green: living and working conditions. Also impact for health: where we work, live… If we have a job
where we are sitting the whole time with no physical activity for 8 hours or you have a lot of physical
activity, but you’re exposed to pesticides during work → this has an impact on your health
• Blue: general socio-economic, cultural and environmental conditions. This is the most global one. This
is for example about country level factors → loss to protect us. Example: no one can smoke in
restaurants. It goes beyond the living conditions of an individual.
Approaches to health
• Individual level: health care professionals (doctors, nurses, psychologists,
physiotherapists…)
• Population level: public health
o Public health (WHO) = “The art and science of preventing disease, prolonging
life and promoting health through the organized efforts of society.”
o Public health has several domains → they all have the common aim to
improve the health of the population
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,1.1.2 What is public health?
• Surveillance: the process used to collect, manage, analyze, interpret, and report information on the
status of diseases, conditions, or populations
o Where (is the problem)?
o Who?
o When?
o → Establish health objectives and priorities
▪ It’s a process where we collect and analyze information about health to give an answer
to these questions
o Example: COVID-19
▪ In the news were everyday
numbers (how many died,
hospitalized…)
▪ It helps people to know what the
problem is and what we need to
do.
▪ We want to know when there is a
problem to do something about it.
o There is also a surveillance system for Polio: to detect outbreaks and to do something about it
• Health services: they look up what kind of health services is needed in which area.
• Disease prevention: 3 types of prevention
o Primary prevention (before the disease).
Examples: keep distance, wash your hands,
stay home if you’re ill…
o Secondary prevention: to diagnose someone
before it’s too late, when we still can do
something about it. Example: training for
breast cancer
o Tertiary prevention: when you already have the disease. Example:
dementia: what can we do about it so it doesn’t go too fast? How can a
person with dementia live longer with less disability?
• Health promotion
o Empowering people about health. Giving information to people so they
know what they must do to improve their own health. Example: promote
active travel.
• Health protection:
o The people in public health institutes. Example: analyzing
water to know that this drinking water has no hazards or
toxicity. Other example: food safety
o It’s also about air quality: air quality is monitored
daily and the EU sets regulations to protect the
population and the WHO sets recommendation
▪ WHO updated their recommendations
last year
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, 1.1.3 What is environmental health?
“Environmental health” covers all physical, chemical
and (non-infectious) biological factors external to the
human body, which may affect health.
• Flu virus is not a factor of environmental
health
• We can have a diet and a health effect. Example: french fries, if you eat a lot of fries, you have a high
intake of fatty acids → obesity… This is not environmental health! → This is nutrion heatlh
• What is environmental health then? There is acrylamide → low birth weight, cancer…
Disciplines
• Environmental toxicology: study of causal mechanisms between exposure and subsequent development
of disease in animal models or cells. (experimental research, lab work)
• Environmental (and occupational) epidemiology: study of associations between exposure to
environmental/occupational agents and subsequent development of disease in populations.
o They look at populations. They look at wat the toxicologist showed them, and they observe
what happens on people. Try to translate the experimental research of toxicologist in real life.
• Health protection: sub-discipline of public health that has the objective of minimizing the exposure to
health hazards in order to protect the population by ensuring environmental, occupational, toxicological
and food safety.
• Policy: legislation to protect the population.
Toxicologists and epidemiologists kind of work together. It
goes in both directions: sometimes epidemiologists also
support the toxicologists
1.2 Historical case studies
1.2.1 Belgium: The Meuse Valley fog of December 1930
One of the most heavily industrialized areas of continental Europe.
Steelworks, zinc smelters, glass manufacturers, and fertilizer and explosives
plants.
Because of climate, there was in December for a few days a very thick fog all over
Belgium, so not only in this area. But in this area, it was worse.
They saw an increase of respiratory problems and an increase in number of deaths
in this area. Normal: 6 deaths in 2 days, now 60 deaths in 2 days.
In the Meuse Valley: >10 times the normal
mortality rate
It got international media attention.
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, Why the Meuse Valley? → special meteorological conditions.
• Anticyclonic conditions (high atmospheric pressures)
• Very feeble (1–3 km/h) easterly wind (from Liège into the valley).
• Temperature inversion above the chimneys in the valley
→ Persistent fog in the valley with accumulation of emitted gases and impurities.
What was the cause of symptoms and death?
• Fumes, gases and dusts released by the local industry → about 30 substances
• SO2 was the only one released at enough concentration to cause symptoms and death.
1.2.2 UK: The London fog of December 1952
London’s winter smog since industrial revolution
• Industry
• Burning coal for heating
• Meteorology
December 1952:
• Unusually dense fog
o Theaters needed to close,
because you couldn’t see what
they were doing→ there was even
indoors fog
• Increase in hospitalizations and deaths
4000 excessive deaths during the week of fog; 8000
deaths in total
→ SO2 levels are very high
1.2.3 Spain: Asthma outbreaks in Barcelona (1981-1986)
Investigation of 12 asthma outbreaks → Initial report of 6 asthma outbreaks between 1981 and 1983, based on
ER admissions of one hospital. Characteristics:
• Unusually severe asthma crises
• Admitted to ER within a 4h period
• Onset of symptoms right before admission
→ Initial hypothesis: acute increases in air pollutant concentrations (SO2 and NO2)
Further investigation:
• Contacting all hospitals
• Demographics and health of patients
• Place of residence of patients
• Time when the symptoms started
• Location when the symptoms started
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