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Let’s start with a simple example of a gallon of kerosene which probably is only a hazard until we light a match nearby, when we actually make the situation risky for the people and property around. Unsafe working conditions are workplace hazards which, when combined with existing vulnerabilities, may translate into potential risk for employees as well as businesses. Similarly, suppose an earthquake occurred in a faraway barren land. It basically remains a natural hazard, not taking environment into account for a while, until the shaking extends to a densely populated area making the situation very risky all of sudden.
In the risk examples above, there are both hazard and vulnerability involved. During risk analysis, one works on studying, identifying and predicting various ways in which a hazard, in combination with possible vulnerabilities or exposures, may pose risk to people, planet and businesses. Simply put, a hazard, under certain vulnerable circumstances, may give rise to risky situations. A comprehensive risk assessment approach would provide us insight into the likelihood of hazard occurrence as well as its extent of impact due to various types of vulnerabilities and exposures involved.
In simple terms, risk assessment can be understood as a methodology that makes it easier for us to understand the nature and the extent of a risk. If we could express a risk in quantitative term, it would simply be the product of probability (likelihood of occurrence) and severity (extent of impact) of an identified hazard; natural, technological or man-made.
Assessing the multifaceted nature of risk both hazard and vulnerability should be taken into account. In this regard, hazard assessment and vulnerability assessment would provide a good picture of probability and severity respectively. Further the risk assessment would provide us insight into the nature of hazard, its potential impact and ways to mitigate the risks. In disaster management context, risk assessment is taken as an integrated approach, including hazard and vulnerability assessment, towards disaster risk mitigation and vulnerability reduction.
Hazard assessment estimates the potential impact of a hazard and probability of its occurrence. The assessment process involves past disaster events, historical data, satellite images, geological information, and land use maps, etc. While analyzing the disaster risks, it is also imperative to analyze vulnerability factors which could make the region vulnerable. Vulnerability assessment basically helps to extend the findings from hazard assessment and is an important component of the comprehensive risk assessment process. It involves the study of hazard proneness, socio-economic factors as well as lack of resources.
In the field of Environment, Health & Safety (EHS), often the probability of a hazard is specifically interpreted in terms of its frequency and the severity of hazard is interpreted in terms of fatality, damage and economic losses, the event may cause. After identifying a hazard, it is then compared and analyzed against those interpreted data to predict the likelihood of accident/disaster occurrence and the extent of its potential impact. The idea is to categorize the types of risk involved and prioritize the mitigation measures. Disaster management institutions around the world continue to improvise and use this risk assessment technique in various Disaster Risk Reduction (DRR) applications.
Quantitative risk assessment technique often involves plain arithmetic. For example, suppose the population of the Kathmandu valley is 2 million and an average 200 people are killed in road accidents annually, hence the annual risk of being killed in a road accident is one in 10,000 (2,000,000/200). However, this method provides crude data and does not include variables such as the effect of traffic, population, road conditions, etc.
Using statistical analysis, risk posed by a hazard can also be related to other parameters such as, proximity, demography or socio-economic factors, while conducting a disaster risk assessment. For example, the rate of urban growth (Socio-economic factor) can be one of the determining factors of the number of road accidents. Similarly, people living around a chemical plant are vulnerable to chemical disasters but, unlike straight-forward quantitative risk assessment, the statistical analysis can also provide us with varying level of risks to the nearby population, depending on their location or proximity to the chemical plant.
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