45:211: environmental geography module 11 hazard and risk

45:211: Environmental Geography

Module 11Hazard and Risk


Learning Objectives

• Hazardous and Toxic materials– Toxic waste

• What is Hazard?– Natural and Anthropogenic– Hazardous places – Spatial and Time aspects


Learning Objectives

• What is Risk?– Assessment, Estimation, Evaluation and

Management• Magnitude and Frequency analysis

• Geography of Risk


Hazardous Materials

• Materials having one or more of the following characteristics:– Ignitability (fire hazard), Corrosiveness,

Reactivity (unstable), Toxicity

• Each year, roughly 1,000 new chemicals are produced and distributed.– Chemical products and by-products of industry

are often handled and disposed of improperly.


Hazardous versus Toxic

• Toxic - refers to substances that cause acute human injury or death.

• Hazardous - a broader term, referring to all dangerous materials that pose a human health or environmental problem.

• Effects depend on level of exposure and tolerance thresholds– Thus we have quality standards/objectives


Toxic Wastes ...

• Cause or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating illness; and

• Pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, disposed of, or otherwise managed.


Setting Regulations• Identification of Hazardous &Toxic Materials

– List often limited to current known offenders– New materials appearing all the time

• Setting Exposure Limits– Nearly all substances are toxic in sufficient

quantities– There are species-specific thresholds– Science of detection (limits of detection)


Hazardous Waste Dumps: The Legacy• Prior to mid 1970s, hazardous waste was essentially

unregulated.– Most common disposal solution was to bury or dump

the wastes without explicit concern for environmental or health risks.

– When sites became full or unnecessary, they were simply abandoned.

• In North America, there are over 25,000 sites containing hazardous wastes.– Where are they?


What is Hazard?

• An event or condition with the potential for causing harm, injury or damage

Severe flooding in the Red River Valley, Manitoba, 1997


Nature of Hazards

• Anthropogenic - created by humans, such as:– toxic chemicals, oils spills, air pollution, etc.

• Natural - extreme events such as:– tornadoes, hurricanes, floods, droughts,

volcanoes, landslides, avalanches, etc.


Consequences of Hazards• Health and safety (public and individual)

– acute and chronic

• Environmental impact– damage to ecosystems– bioaccumulation– keystone species

• Economic losses– property damage– loss of livelihood


What is Risk?

• Definition: the probability of occurrence of a hazardous event.– A measure of the likelihood of an adverse effect

to health, property or the environment.

• In other words, exposure to the chance of loss/harm, within the context of some expected net benefit.

Risk = Hazard x Exposure


Risk Assessment

• What can go wrong? – Hazard identification

• How likely is it? – Risk estimation

• What are the consequences? – Risk evaluation - who or what suffers harm or

injury


Hazard Identification

• Those hazards which generate risk of harm or injury in a particular place or situation– Based on experience and historical records– Based on medical evidence– Event Tree Analysis– Environmental Assessment


Risk Estimation• The use of available information to estimate

the probability of occurrence of a harmful event or condition – the harm to human health or the environment that

may result from exposure to pollutants, toxins, or extreme “natural” events.

• E.g. How likely are:– Toxic spills, oil spills, chemical releases,

earthquakes, tornadoes, flooding, etc


Risk Estimation Involves ...

• Determining likelihood of occurrence: e.g.– as based on frequency analysis of historical

data


Flood Level Data

0

2

4

6

8

10

# O

bse

rvat

ion

s

1 2 3 4 5 6 7 8 9 10

Discharge Category

Annual Peak Discharge, Rideau River


Return Interval Analysis

Large events are increasing in frequency - a result of climate change?

Large events are less frequent


Practical Application• Estimates of the magnitude and frequency of

floods are used by engineers in the design of bridges, culverts, dams, and embankments, and by land-use managers to assess the hazards related to the use and development of flood plains.– This is known as the design event– But there will always be an event that’s bigger

than the design event Consequences?


Return interval: the spatial aspects of risk


Risk Evaluation

• A process that identifies the consequences associated with a hazard.– Provides a basis for decisions

concerning acceptable risk, by comparing the results of risk analysis with harm criteria.

• E.g. air quality objectivesFrozen Orange Juice!


Risk Evaluation

• Do the consequences matter?– What is an acceptable level of harm?– What is judicious risk-taking? – What is the proper allocation of responsibility

for risky activity?

• Who suffers harm from what?– Socio-economic factors – Geographical factors


Perception of risk

• Everyone engages in some form of risky behaviour:– Examples?– But the perception of risk is heightened by the

fear of falling victim unfairly to uncompensated loss. (A random act or occurrence)


Risk Management

• Can we avoid risk?– No.

• Can we expose ourselves to greater risk?– Yes. By using or modifying the environment

without thought, by settling on marginal lands.

• How can we reduce risk?– Zoning, planning, regulation, building codes,

safety standards, clean up of hazardous materials


Risk Distribution

• Spatially - earthquake zones, flood plains, toxic waste dumps, etc.

• Through time - extreme event probability

• Socio-economically- who suffers damage, harm and death?– Who lives near dumps and industrial plants?– Who can protect themselves from risk?


Hazardous Places

• Are all places equally vulnerable? No.– Hazards are spatially distributed (they are

geographical)

• What makes a place hazardous?– What kinds of hazards are there?

• Including secondary hazards (e.g. landslides triggered by earthquakes or heavy rains)

– What hazards do we have here in our region?


So, where you live matters

• There are different types of hazards

• Different levels of occurrence

• Do you have choices?– Socio-economic factors

• Environmental justice

– Perception of risk• The fear of falling victim unfairly to uncompensated

loss.


Hazard of Place


Hazard of Space


We can make matters worse ...

• Events that are typically classed as natural may be caused or worsened by human actions. For example:– The severity (and frequency) of flooding may

be exacerbated by channelisation, floodplain reclamation (infilling wetlands), deforestation and other land use changes.

• The Saguenay floods.

• Other examples?


“Natural” disasters represent the intersection of two sets: nature and population. As the population continues to grow, so does the area of intersection, leading to costlier and perhaps deadlier disasters.


Summary

• Risk assessment uses facts and assumptions to estimate probability of harm from hazardous events and conditions– Hazards are natural and human-made

• Risk management depends on socio-economic and political factors as well as the adequacy of scientific evidence

• Hazard and Risk have geographical (spatial) aspects.

45:211: environmental geography module 11 hazard and risk

Documents

environmental geography

toxic toxic

environmental problem

hazardous wastes

toxic materials toxic

hazardous event

toxic chemicals

human health