Safety Analysis

Principles and Practice in Occupational Safety

Lars Harms-Ringdahl

• Publisher: CRC Press
• Year: 2001
• Print ISBN: 9780367397180
• eBook ISBN: 9781134561926
• Topic: Technology & Engineering
• Subtopic: Industrial Engineering
• Index: Technology & Engineering

Safety analysis can be applied as a practical tool in occupational safety. It has three main elements: the identification of hazards, the assessment of risks that arise, and the generation of measures to increase the level of safety. A number of simple methods are described that can be used in industry and the workplace, such as deviation analysis,

1
Accidents and safety

1.1
THE ACCIDENT PROBLEM

Introduction

Risks and accidents are serious problems from many different perspectives. Some of these are discussed as background to the need for accident prevention and related tools. This section takes up some aspects of accidents and the magnitude of the accident problem—both in general and in a workplace setting.

Accidents world-wide

From a global perspective, accidents are a major health problem. Each year, there are nearly three million fatalities resulting from accidents or poisoning, of which two million occur in less developed countries (Karolinska Institutet, 1989). According to the same source, injury is the primary cause of death among children and young men in virtually all countries. The medical, social and lost-productivity costs of all injuries are estimated to exceed 500 000 million US dollars each year.

In the USA, an annual total of 4.1 million life-years are lost as a result of accidents and injuries (Committee on Trauma Research, 1985). The corresponding figures for heart disease and cancer are 2.1 and 1.7.

The World Health Organiation (WHO) maintains an international database founded on medical records. Of special interest here are statistics on injuries, since “accidents” are not directly entered into the data set. As seen in the definition below, “accident” corresponds to “unintentional injury”, but has a slightly different meaning.

A specialised study of the importance of injuries has been conducted by Krug (1999): “An injury is a bodily lesion at the organic level resulting from acute exposure to energy (mechanical, thermal, electrical, chemical or radiant) interacting with the body in amounts or rates that exceed the threshold of physiological tolerance. In some cases (e.g. in drowning, strangulation or freezing) the injury results from an insufficiency of a vital element. The time between exposure and the appearance of the injury needs to be short.” Injuries are often classified as unintentional or intentional. Most traffic injuries, fire-related injuries, falls, and cases of drowning and poisoning are regarded as unintentional. By contrast, homicides, suicides and war-related injuries are categorised as intentional.

It is estimated that 5.8 million people died from injuries world-wide in 1998 (Krug, 1999). This corresponds to a rate of 0.98 per 1000 persons. The death rate for males was almost double (a factor of 1.92) that for females. A conclusion of the study was that injury is the leading cause of death in all age groups. It should be remembered that for every person that dies, several thousands more are injured, many of them permanently disabled.

The magnitude of the problem varies considerably by age, sex, region and income. For example, in the low- and middle-income countries of the Western Pacific the leading injury-related causes of death are road-traffic accidents, drowning and suicide, whereas in Africa they are war, interpersonal violence and traffic. In the high-income countries of the Americas, the leading injury-related cause of death among people aged 15 to 44 years is traffic, whereas in the low- and middle-income countries it is interpersonal violence.

WHO’s injury statistics do not identify where injuries occur. This means that the data do not permit comparisons between hazards at work, in traffic, in the home, etc. Information about occupational accidents must come from other sources.

Occupational accidents in the world

Occupational accidents are in themselves a major problem from a world perspective. The International Labour Office (ILO) compiles statistics for occupational accidents and diseases. According to one estimate, 180 000 people a year die from accidents at work, while 110 million are injured (Kliesch, 1988). In a large number of countries, both industrialised and less developed, the frequency of fatal accidents has fallen since the 1960s. For example, it fell—over two decades—by 70% in Japan and Sweden, and by 62% in Finland (Kliesch, 1988). Similarly, the frequency of serious injuries is also falling, at least in industrialised countries. The explanations usually provided for this are that there are fewer people in hazardous occupations and that workplaces have become safer.

These figures are high, but they are also highly uncertain—partly due to missing data. A more recent summary (Takala, 1998) shows still higher figures. For the whole world, the estimated average fatal occupational-accident rate in 1994 was 14 per 100 000 workers. And the total estimated number of fatal occupational accidents was 335 000. Rates differ between individual countries and regions, and also between separate branches of economic activity.

Table 1.1 Number of work-related fatalities world-wide during 1994 (from Takala, 1998).

Table 1.2 Fatal ccupational accidents in the world in eight different main regions during 1994. Fatality rate is given as number of deaths per 100 000 workers (adapted from Takala, 1998).

An estimate was also made of the total numbers of deaths related to the workplace (Table 1.1). In total more than 800 000 persons died during 1994. Data and sources of failures have been analysed, and corrections made accordingly. 1.1 million can be considered the best available estimate of annual work-related deaths world-wide. This means that 3000 deaths are caused by work each day (Takala, 1998).

A comparison has also been made between a number of countries around the world, as divided into eight major regions (Table 1.2). In total, the size of the world labour force is estimated at 2.7 billion. The inter-country regional fatality rate varies considerably. For the “Established Market Economies” the range in the rate between countries is 1.4–10.

The incidence of non-fatal accidents has also been estimated. A ratio of 750— between non-fatal and fatal accidents—has been used to provide a foundation for an ILO estimate of non-fatal occupational accidents. The injuries then include 250 million occupational accidents and 160 million cases of occupational disease. These figures are based on relatively conservative estimates (Takala, 1998).

On the costs of accidents

Occupational accidents are also of economic importance—for society, for employing organisations and for the injured persons. At a societal level, the costs are considerable, but difficult to discern and calculate. They are borne by different parts of the health-care system, insurance companies, and so on.

An overview of cost estimates (Dorman, 2000) was recently published by the International Labour Office (ILO). In general, there are many difficulties involved in making such estimates, and it is necessary to make a large number of assumptions. Such studies may be helpful, but should be seen as order-of-magnitude estimates. Estimates have been made for Europe and the USA, but there are no comparable studies of the economic costs of occupational ill-health in the developing world (at any level).

One cited study concerns nine selected European countries (Beatson and Coleman, 1997), which estimates the aggregate economic costs of occupational injury and disease by country. Most costs are in the range 2.5–6% of Gross Domestic Product (GDP).

Another study estimates the economic costs of fatal and non-fatal occupational injuries and illness during 1992 in the USA (Leigh et al., 1996). The total cost was estimated to be 173.9 billion US dollars, corresponding to approximately 3% of US GDP. This was considerably higher than the cost as estimated by Dorman (2000). The greatest cost was related to non-fatal injuries (at 144.6 billion US dollars), while that related to fatal injuries was much lower (at 3.8 billion US dollars). The study also included an estimate of who pays. Based on a number of assumptions, it was concluded that workers bear about 80% of the costs (in one way or another).

The results were summarised by Dorman (2000) as follows:

1. The overall share of occupational injury and illness costs in a typical developed-country economy is substantial, not less than 3% of GDP.
2. Costs may be significantly larger than this, due to the difficulty in identifying the incidence of occupational disease.
3. Workers’ compensation plays a significant economic role in determining who bears the costs of disability and premature death.

In general, it can be stated that the total cost of accidents varies considerably between employing organisations. The significance of costs depend on which types of insurance and compensation systems are operated and how sensitive production is to disturbances. Heinrich (1931) and Brody et al. (1990) found these costs to be relatively high. But another study (Söderqvist et al., 1990) indicated that the marginal cost of accidents to companies was very low.

Reasons for this were that comprehensive insurance policies covered compensation to injured persons, that insurance premiums were independent of the number of accidents, and that there was a certain surplus of personnel.

At a personal level, an accident can create difficulties for the individual in a large number of self-evident ways. There is, however, a long tradition in many countries that people injured at work receive compensatory insurance payments.

Risks at an individual level

People in society engage in a large number of activities, which are hazardous to a greater or lesser extent. The level of risk varies considerably from activity to activity. The ways in which individuals perceive risks and act more or less safely depend on a range of factors. The relations involved have been studied for a long time (e.g. Fischoff et al., 1981) and have become a subject area in their own right. There are explanations related to cultural, economic and other factors, as well as type of risk. In general, higher risks seem to be tolerated in voluntary activities where the individual has a certain degree of control over what is happening. Also, the individual generally obtains some benefit from what he or she is doing.

For many activities, however, risks are not taken on voluntarily; nor does the individual have much control over...

Table of contents

• Cover
• Title Page
• Copyright Page
• Preface
• 1 Accidents and safety
• 2 Features of systems and accidents
• 3 Safety analysis
• 4 Risk assessment
• 5 Energy Analysis
• 6 Job Safety Analysis
• 7 Deviation Analysis
• 8 Hazard and operability studies
• 9 Fault Tree Analysis
• 10 Analysis of safety functions
• 11 Some further methods
• 12 Methodological overview
• 13 Safety analysis—planning and implementation
• 14 Theoretical aspects
• 15 Examples of safety analysis
• 16 Concluding remarks
• 17 References
• 18 Index