Determination of individual risk. Acceptable individual risk Work procedure
A direct answer to the question of how to calculate risks is provided by the methods of reliability theory. These methods are based on combining block diagrams of complex technical devices and probability theory, taking into account the human factor. The meaning of risk can be different:
1) for each dangerous connection in an ergatic system, i.e. a system one of the elements of which is a person, the individual risk for the i -th person from the j -th danger is the annual frequency of the share of danger realization:
where nj is the number of victims of the jth type of hazard, people;
Nj -- number of people exposed to the jth type of hazard, people;
F - time during which the events occurred, year;
Other possible risk assessment methods include risk matrices, cause trees, event trees, etc.
As an illustration, I will list only some of the most commonly used risk concepts and corresponding indicators, widely discussed in Lately: insurance risk, professional risk, individual risk, collective or group risk, potential territorial risk, social risk, expected damage, risk coefficient, risk index, classes of working conditions according to the degree of harmfulness and danger, classes of professional risk of enterprises, categories of proof of risk, etc. .d.
This abundance of concepts reveals a tendency towards the finest possible differentiation of concepts and risk indicators.
Risk R can be described as the usual product of the frequency of a dangerous event Pdangerous event by the severity of the consequence Slast: R = Pdangerous event Slast.
The concept of severity (seriousness) of a consequence in a certain sense may include the damage of a given consequence, expressed in monetary equivalent.
Individual risk differentiated by the nature or severity of the lesion. For example, a distinction is made between the individual risk of general injuries and the risk of fatal injuries, and each of these types of risk is further differentiated by economic sector, etc.
The individual risk indicator is most often used in risk analysis due to the simplicity and clarity of this concept. Let us give examples of calculating individual risk.
Example 1. Let us determine the risk R of a person dying at work in our country for 1 year, if it is known that about n = 7 thousand people die annually, and the number of workers is approximately N = 70 million people:
Example 2. Every year in Russia, about 500 thousand people die due to various dangers of unnatural death. Taking the country's population to be 145 million people, we determine the risk of death Rstr of a country resident from dangers:
Example 3. Let us determine, using the data from previous examples, the risk Rd of getting into a fatal accident associated with a traffic accident, if 35 thousand people die in these incidents annually:
The risk of death in different industries varies widely. From 110-2 per person per year in the production of mustard gas to 110-6...110-5 in the clothing and footwear industries. If we take all industries, then the average risk of death from professional activity has remained virtually unchanged over the past 50-60 years and is currently about 610-4 per person per year. This means that every year out of 1 million workers in various industries, 600 die due to exposure to factors of production activity.
Thus, the level of risk that has remained virtually unchanged for a long time, determined by the sum of production factors, despite the expansion of production, can be considered as socially acceptable. In other words, at this stage society can tolerate a risk level of 610-4 per person per year, given the benefits it derives from production activities. The above values correspond to the risk of death from disease at the age of 30, that is, when it is minimal.
As for the risk of death caused by the internal environment, that is, as a result of various types of diseases and aging, it averages 110-2 per person per year on the planet. This means that out of 1 million people, including all age groups, 10 thousand die annually from disease and old age. It should be noted that the risk of death from malignant neoplasms of various organs and tissues is 210-3 per person per year, and the leading one is the risk of death from cardiovascular diseases, which is equal to 510-3.
In the process of life, a person is exposed to factors of the natural environment. These include earthquakes, floods, hurricanes, thunderstorms, etc. They cause the death of 10 out of 10 million people every year. Thus, the risk of death due to natural habitats is approximately 110-6 per person per year.
Collective, or group, risk is simply related to individual risk: that is, the collective risk for a group of people is equal to the individual risk (for one person) multiplied by the number N of people in the group.
Example 4. Individual risk fatal outcome when smoking (one pack per day) is 3.610-3 1/year. It is necessary to find the collective risk of death from smoking in a country with a population of 145 million people, if the proportion of smokers is 0.4 of the total population. According to definition collective risk, for this group of people we have:
Rcol = 0.41451063.610-3 210103,
that is, more than 210 thousand people can die annually from lung cancer caused by smoking.
To characterize working conditions (factors production environment, heaviness and tension labor process), not responding regulatory requirements, it is advisable to introduce the concept of production risk (not to be confused with occupational risk, which is determined by the ratio financial indicators compensation for harm and wage fund for certain period).
To simplify, you can take into account the presence of at least one harmful or dangerous production factor that does not meet the requirements regulatory documents. The presence of such a factor can contribute to the occurrence of a work-related disease, lead over time to an occupational disease, become a prerequisite for general diseases, or provoke an accident at work.
Example 5. According to official statistics, in 2003 in Russia, 2.4 million people (n) were employed in industry, construction, transport and communications enterprises in conditions that did not meet the requirements of sanitary and hygienic standards. Total number those working in these industries (also according to statistical data) amounted to 10.3 million people (Nlab). Production risk in 2003, according to these data, was equal to
Rpr = n/Nwork = 2.4106/(10.3106) = 0.23.
Note that Rpr = 0 if all jobs correspond regulatory conditions labor, and Rpr = 1, if none workplace does not meet sanitary and hygienic standards in at least one parameter.
Potential territorial risk is the frequency of occurrence of the damaging factors of an accident, catastrophe, or environmental disaster at a given point in the territory.
The distribution of potential territorial risk for a given hazardous event resembles topographic map, which, using isolines and corresponding figures, shows the maximum values of the frequency of fatal injuries to humans in one year for each point of the facility site and the adjacent territory. The frequency or risk of fatal injury to a person is determined based on his permanent location at a given point.
Such distributions of potential territorial risk are widely used in the analysis emergency situations and designing measures to prevent them. In the case of explosions and releases during accidents, such risk distributions should include both accident scenarios with the same mass release in all wind directions, and the affected area for a separate scenario for a given (preferred) wind direction.
Example 6. The epicenter of the explosion has a radius r0 = 2.3 m - this is the zone of 100% damage. Assuming the isotropy of the explosion and the normal distribution of damaging factors, it is necessary to find the isoline radii for the potential territorial risk values of 10-3 1/year and 10-6 1/year. Normal distribution R(r) of potential territorial risk as a function of the distance to the epicenter of the explosion has the form
where e = 2.718 is the base of the natural logarithm. Calculation of the coefficient gives: = 0.04 1/m2. Substituting the values of the given territorial risks for two unknown radii of isolines, we find r1 and r2: R1 = 10-3 = r1 = 8.7 m, R2 = 10-6 = r2 = 12.2 m. Thus, within a radius of 9 m from epicenter, the probability of human injury remains very high.
Social risk characterizes the severity or catastrophic nature of the consequences of a dangerous event. A well-known specialist in the field of security and risk theory, B. Marshall, defines social risk as “the dependence of the risk (frequency of occurrence) of events consisting of the defeat of a certain number of people exposed to damaging influences certain type when certain dangers are realized, from this number of people; social risk characterizes the scale of the catastrophic nature of the danger.” Often for analysis social risk methods of probability theory are used, since social risk is a discrete distribution of the probability of a dangerous event by the number of victims N.
Expected damage is the mathematical expectation of the amount of damage when a hazardous event occurs over a certain period of time.
Expected damage is usually expressed in monetary terms and most often takes into account damage material property. It is subject compulsory insurance, since it includes not only damage to production facility, but also possible environmental damage. Any organization also carries out mandatory social insurance from accidents at work.
Expected damage, like social risk, is a non-trivial characteristic of a dangerous event from the point of view of probability theory, allowing for subtle differentiation in the analysis of causes and consequences.
The damage to a person can be varied: the risk of death, the risk of injury, the risk of illness, etc. To compare any types of hazard, the risk of death from them is determined rijyears. Then the damage from the realization of the danger will be:
x r i.j = rijletxo,
where Xo is the cost of human life.
For ri.jyear = 1 we have Хrij = Хo. That is, the damage associated with the death of a person is the cost of human life, and therefore risk is an economic category. This approach raises objections from a certain circle of people who argue that human life is sacred and not subject to monetary valuation.
However, in practice, the need for such an assessment inevitably arises precisely for the sake of human safety, if the question is posed as follows: “How much money must be spent to save a human life?” According to foreign studies, human life is estimated at between 650 thousand and 7 million US dollars.
Risk calculation problem
- 1.5 minutes of mountaineering corresponds to an individual risk of death of 1?10-6 year. Determine the annual number of dead climbers, if over the past 3 years 40 thousand people went to the mountains, while each climber spent 2.5 days directly on the climb
- 1.5 min = 0.025 hour
- 2.5 min = 60 hour
- 40000:3?60 = 8?105 people/hour
- 8?105:0.025?1?10-6=32 people
Danger– one of the central concepts of life safety (LS). Danger lies in all systems that have energy, chemically or biologically active components, as well as characteristics (parameters) that do not correspond to the conditions of human life. It can be said that danger is the risk of adverse impact.
Practice shows that absolute safety unattainable. The desire for absolute security often comes into antagonistic contradiction with the laws of the technosphere.
In September 1990, the first World Congress on Human Life Safety was held in Cologne scientific discipline. The motto of the congress is: “Life is safe.” Congress participants constantly used the concept of “risk.”
The following definitions of risk are possible:
There are real and potential dangers. It is accepted as an axiom that any human activity is potentially dangerous. Implementation potential danger occurs through causes and leads to undesirable consequences.
Now specialists are faced with the task of not excluding security to zero (which is impossible in principle). And the achievement of a predetermined value of the risk of the danger occurring. At the same time, compare the costs and benefits obtained from risk reduction. In many Western countries For a more objective assessment of risk and the resulting costs and benefits, a financial measure of human life is introduced. Note that this approach has opponents, their argument is that human life is sacred, priceless and some financial estimates unacceptable. However, according to foreign studies, human life is assessed, which makes it possible to more objectively calculate insurance rates for insurance and justify the amount of payments.
Since absolute safety (zero risk) is impossible, modern world came to the concept of acceptable (tolerable) risk. The essence of the concept is the desire for such security as is accepted by society at a given time. This takes into account the level technical development, economic, social, political and other opportunities. Acceptable risk is a compromise between the level of security and the possibilities of achieving it. This can be considered in the following situation. After a major accident on Chernobyl nuclear power plant, the USSR government decided to improve the reliability of all nuclear reactors. Funds were taken from the state budget and, consequently, funding decreased social programs health, education and culture, which in turn led to an increase in socio-economic risk. Therefore, it is necessary to comprehensively assess the situation and find a compromise between costs and the amount of risk.
The transition to “risk” gives additional features increasing the safety of the technosphere. In addition to technical, organizational, and administrative ones, economic methods of risk management are added (insurance, monetary compensation damage, risk payments, etc.). Eat common sense is to legally introduce risk quotas. This raises the problem of risk calculation: statistical, probabilistic, modeling, expert assessments, opinion polls etc. All these methods provide a rough estimate, so it is advisable to create databases and data banks on risks in the conditions of enterprises, regions, etc.
Practical problems
Task 1. Table 1 shows a number of professions according to the degree of individual risk of fatal outcome per year. Using the data in Table 1 using the method of expert assessments, characterize your current activities and the conditions of your future work.
Table 1. Occupational safety classification
After the discussion, put your assessment in writing.
To solve the following problems, use the formula for determining individual risk
where P is individual risk (injury, death, illness, etc.);
N – the number of occurrences of a hazard with undesirable consequences over a certain period of time (day, year, etc.);
N – the total number of participants (people, devices, etc.) affected by the danger.
Example solving the problem using formula (1).
Condition. Every year, 250 thousand people die from unnatural deaths. Determine the individual risk of death of a resident of a country with a population of 150 million people.
Solution.
R w = 2.5*105 /1.5*10 8 =1.7.10 -3
Or it will be 0.0017. Otherwise, we can say that every year approximately 17 out of 10,000 people die an unnatural death. If we fantasize and assume that a person’s biological life span is 1000 years, then according to our data it turns out that after 588 years (1:0.0017) the probability of a person dying from an unnatural death is close to 1 (or 100%).
Task 2. The danger of death at work occurs 7 thousand times a year. Determine the individual risk of fatalities at work, provided that there are 60 million people working in total. Compare the result with yours expert assessment from task 1.
Task 3. Determine the risk of fatalities in a road traffic accident (RTA), if it is known that 40 thousand people die in road accidents annually in a population of 150 million people.
It is known that the probability of death in various types of
professional activity is (0.2 – 3) 10 -7 person/hour, on average – 0.7 10 -7 person/hour, while doing housework – 0.5 10 -7 person/hour.
In addition to individual risk, there is also a social risk, which characterizes the likelihood of a certain number of people being affected if a particular danger occurs. It determines the scale of the catastrophic nature of the danger.
For practical purposes, in particular to justify preventive measures, it is important to know the actual and calculated (predicted) risk values. The actual values of various risks can be calculated from statistical data on accidents, diseases, accidents, fires, natural disasters. If in any country C people died from all types of hazards, and the entire population was H, then the individual risk of death Rtot from all dangers will be
Rtot = X / H. (1.1)
If we consider only production activities, then the risk of death at work will be
R pr = X pr / P, (1.2)
Where X pr– death toll in all industries National economy; P– total number of employees.
It is important to note that R pr usually much less Rtot.
For individual sectors of the economy we have
R neg = X neg / P neg, (1.3)
Where X negative And P negative respectively, the number of deaths and the number of workers in the industry in question.
Based on values Rtot, Rpr, Rneg, it is possible to solve many issues of life safety management: justify the volume of allocations for the purpose of increasing safety, establish the level of safety requirements through the relevant regulatory legal acts(standards, rules, norms), insurance rates for insuring workers against accidents at work and occupational diseases. At the same time, the most effective management risk is achieved through changes made to equipment and technologies at the stage of development of the corresponding project documentation. To establish the content of these changes, the risk must be expressed through specific technical and technological characteristics of the object or process, i.e. it is required to obtain a mathematical model for risk prediction. Such models are built using the principle of decomposition, according to which a complex object or process is divided into operations, and operations into elementary actions. This approach is due to the fact that only at the level of an elementary action (or an elementary unit of a machine) risk can be expressed through the corresponding specifications the system being studied. However, it is necessary to adopt some model of risk realization and clarify its type. An accident can be accepted as the most undesirable type of risk realization. For many processes, the typical sequence of events leading to NS includes: the occurrence of trauma dangerous situation(PTS) ® presence of a person in a dangerous zone (NOZ) ® exposure to a traumatic factor (PTF) ® failure of protective equipment (FPE). So the risk R ij (D) at the action level (D) is defined as
R ij (D) = P ij (PTS) " P ij (NOZ) " P ij (PTF) " P ij (OSZ), (1.4)
Where P ij (PTS), P ij (NOZ), P ij (PTF), P ij (OSZ)- probabilities, respectively, of PTS, NOZ, PTF, NOS. It is these probabilities that in many cases can be expressed through the technical and technological characteristics of the object or process being studied.
If we assume that the process under study consists of n operations, and each operation from m i actions, then taking into account the independence of events associated with the impact hazardous factors per person in different actions and with different operations we get
R i (O) = , (1.5)
R(P) = 
, (1.6)
Where R i (O)- risk arising when performing i th operation; m i – number of actions in i th operation; R(P)– risk related to the process as a whole; n– the number of operations that make up the process being studied.
Real technological processes characterized by repeating cycles, for example, manufacturing parts, feeding animals, Maintenance cars Therefore, risk calculations are made for one cycle. If, within a unit of time (this could be an hour, a shift, or even a year), N cycles, then the magnitude of the risk will be
R = 1 - N. (1.7)
Assuming that the number of cycles N in formula (1.7) refers to one year, the value R will represent an annual individual risk. Its value should be no more than 1"10 -6. If this condition is not met, then the necessary improvements must be made to the project.
Risk calculations can be performed for individual hazardous and harmful factors. In particular, the risk R(AI) cancer diseases due to exposure ionizing radiation (AI) and when adopting a non-threshold concept, the effect of these radiations on the body can be assessed as
R(II) = k "H, (1.8)
Where k– proportionality coefficient equal to 1.25"10 -2; H– equivalent absorbed dose, Sv.
When exposed to increased noise there is a risk R(L A) permanent loss of hearing sensitivity. It depends on the duration of exposure to increased noise and its level L A, dBA. For the noise exposure time corresponding to five years, the expression is obtained
R(L A) = (197.7 – 4.87"L A + 0.03"L )/100 (1.9)
Risk R(a eq.) vascular disorders when exposed to local vibration transmitted to human hands, according to ISO 5349 is equal to
R(a eq) = 
/ 95, (1.10)
Where A eq(8) – equivalent adjusted value of vibration acceleration for a duration of exposure to local vibration during a shift of 8 hours; T– duration of work in vibration-hazardous conditions, years. Expression (1.10) cannot be applied if the values T are outside the range (1-25) years, and the values R(a eq) – (0,10-0,50).
Earthquake risk can be determined according to the model
P(N,t) = (l"t) N exp(-lt/N!), (1.11)
Where P(N,t)– probability of occurrence of N earthquakes during a time interval t; l is the average number of earthquakes per unit of time, obtained from statistical data.
Risk of epidemic disease R e (t) is approximately estimated by the expression
R e (t) = (Q + 1) / (Q), (1.12)
Where Q– the number of healthy people in which the sick person falls, a is the proportionality coefficient established for each type of pathogenic microbes and the conditions for the spread of the epidemic; t– the point in time from the beginning of the epidemic.
Hazard classification. The range of hazards changes in the course of scientific and technological development, which often gives rise to previously unknown hazards. According to the nature of origin, hazards are divided into technogenic, anthropogenic, social, natural; by localization – into those associated with the lithosphere, hydrosphere, atmosphere and space. According to the consequences caused, hazards can be associated with diseases, death and injuries of people and animals, death and diseases of plants, fires, accidents, floods, droughts, etc. Depending on the type of activity, hazards can be industrial, road transport, household, sports, or military. Based on the nature of the impact, hazards are divided into passive and active. Passive dangers are distinguished by the fact that they are activated by the person himself using his own energy - protruding nails, other sharp, piercing objects, uneven surfaces, steep climbs, slopes, unprotected differences in height. Active hazards affect people independently - a shock wave, light radiation from a nuclear explosion, high-level noise, ionizing radiation, etc.
By time of manifestation negative consequences dangers can be impulsive (adverse consequences appear immediately) or cumulative (adverse consequences accumulate in the body, eventually leading it to death). pathological condition). Impulsive action is characteristic of electric current and impact noise. Cumulative effects are typical for ionizing radiation, increased noise, insufficient lighting and a number of other hazards. Depending on the level or intensity, the same danger by name can have both a cumulative and impulsive effect on the body.
Taking into account the material essence (material nature of hazard carriers), they can be divided into physical, mechanical, chemical, biological.
The nomenclature or list of hazards can be general, sectoral, local, i.e. refers to one particular object or even one workplace. A very detailed list of hazards was compiled by O.N. Rusak (1996). It included, in particular: cars, alcohol, abnormal air and water temperatures, volcanoes, sparks, pitching, cauldron, meteorites, fire, weapons, pesticides, increased levels of radiation, slippery surfaces, snowfall, noise, physical overload, emotional stress , toxic substances, etc.
In the Occupational Safety Standards System (OSSS), hazards are understood as dangerous and harmful production factors(OVPF). OPF are factors that lead to injuries, HPF – to morbidity (subject to exposure to the employee).
All OVPFs according to GOST 12.0.003 are divided into four groups: physical, chemical, biological and psychophysiological. Physical OVPFs include: moving machines and mechanisms; moving unprotected elements of equipment (shafts, gears, couplings, etc.); moving products, workpieces, materials, collapsing structures, collapsing rocks (or water masses), rocking; increased dustiness, air pollution; increased levels of noise, vibration, radiation, ultra- and infrasound, light brightness; increased or decreased temperature, relative humidity and air mobility, barometric pressure; increased voltage in electrical circuits that can be closed through the human body; sharp edges, burrs on the surfaces of equipment, workpieces and tools; location of workplaces at height.
Chemical OVPF include toxic, irritating, sensitizing, carcinogenic, mutagenic harmful substances, as well as substances affecting reproductive function.
Towards biological CVPFs include pathogenic microorganisms (bacteria, viruses, rickettsia, spirochetes, fungi, protozoa) and their metabolic products, as well as dangerous and harmful macroorganisms and plants.
Psychophysiological CVPF are divided into physical overload (dynamic, measured in J, and static, measured in H "s) and neuropsychic overload (mental overstrain, overstrain of analyzers, monotony of work, emotional overload).
It is important to emphasize that HFPF occurs if any factors of working conditions (or factors of the working environment) deviate from the requirements of current standards, norms and rules in a direction unfavorable for humans.
The concept of individual risk is understood as the probability of injury to an individual over a certain period of time as a result of the influence of the studied hazard factors in the event of an unfavorable random event, taking into account the probability of his stay in the affected area.
From a mathematical point of view, individual risk is defined as the product of the probability of death of a person located in a given region from possible sources of danger throughout the year and the probability of his stay in the affected area.
IN general case Quantitatively, individual risk is expressed by the ratio of the number of people affected for a certain reason to the total number of people who are at risk over a certain period of time (a posteriori definition).
When calculating the risk distribution over the area around the facility (risk mapping), individual risk is determined by the potential territorial risk and the probability of a person staying in the area possible action dangerous factors.
In general, the individual risk from a certain hazard, which is calculated for a certain study area, is characterized by the probability of death of an individual from the population over a period of time - one year. The individual risk assessment (R) can be obtained using the formula:
W = P/N (5.6)
Where P- number of deaths per year due to a specific cause;
N is the population size in the study area in the year being assessed.
IN practical activities this type of risk calculation is the most common. In general, depending on the analysis tasks under P can be understood as the total number of victims, as well as the number of fatally injured or another indicator of the severity of the consequences.
The concept of individual risk must be interpreted taking into account specific types of activities and statistical data regarding accidents (deaths) over a certain period of time that arose as a result of this activity.
In any area where the population lives, regardless of the presence or absence of any man-made objects, there is always some probability that a person will die as a result of a domestic accident, criminal attack or other unnatural event. Average annual risk for specific person depends on the sources of danger and the time of their influence.
The individual risk value is divided into 3 categories:
1) everyday risks (risks to which every resident of the country is exposed, regardless of profession and lifestyle);
2) professional risks (risks associated with a person’s profession);
3) voluntary risks (risks that relate to personal life, in particular non-professional mountaineering, parachute jumping, etc.).
Individual risk is largely determined by the qualifications and readiness of the individual to act in a dangerous situation, his security. Individual risk, as a rule, should be determined not for each person, but for groups of people who spend approximately the same time in different hazardous areas and have the same means of protection. It is recommended to assess individual risk separately for facility personnel and for the population of the surrounding area.
If the risk is assessed for any group of people in a certain profession or special type of activity that is associated with increased danger, it is advisable to determine this risk in terms of a specific work time(for one hour of work or one technological cycle).
The characteristic values of the individual risk of natural and forced death of people from the effects of living conditions and activities are given in Table. 5.2.
Social risk is determined by the number of losses (for example, deaths among the population), which, as a rule, is calculated statistically. It is in many cases synonymous with collective risk.
From tables 5.3 - 5.5 it is clear that the risk of a fatal outcome exists at a level of 10 -7 or higher per person per year. Thus, when designing and operating technical devices, a risk of 10 -7 people/year can be accepted as acceptable under the following conditions:
The problem of risk is analyzed deeply and comprehensively;
The analysis was carried out for decision-making and confirmed by available data in a certain hourly interval;
After the occurrence of an adverse event, the analysis and conclusion about the risk obtained on the basis of the existing data do not change;
Analysis shows, and control results continually confirm, that the threat cannot be reduced at justifiable expense.
Table 5.2 - Characteristic values of individual risk
The accepted assessment of acceptable risk and the specified conditions must be strictly followed and considered as the first step towards quantitative comparison.
Table 5.3 - Probability of death due to outside production reasons
Table 5.4 - Probability of death due to work-related causes
| Branch of the national economy | Event frequency, 10 -7 people/year | |
| Mining work | ||
| Transport | ||
| Construction | ||
| Mining of non-metallic minerals | ||
| Operation of gas pipeline equipment and hydraulic structures | 0,6 | |
| Metallurgical industry | 0,6 | |
| Woodworking works | 0,6 | |
| Food industry | 0,6 | |
| Pulp and paper industry and printing | 0,5 | |
| Electrical engineering, precision mechanics and optics | 0,4 | |
| Chemistry | 0,4 | |
| Trade, finance, insurance, public utilities | 0,4 | |
| Textile and leather and footwear industry | 0,3 | |
| Healthcare | 0,2 | |
| average value. for 20.2 million insured persons | 0,7 |
Table 5.5 - Probability of death in different areas human life
If we are talking exclusively about the risk of material losses, the comparison method for assessing risk is beyond doubt. In this case, you can make a decision by assessing only the economic effect.
The essence of standardization, regulation and management of security in its main components (socio-economic, military, scientific and technical, industrial, environmental, demographic) using risks comes down to the requirement not to exceed the magnitude of risks Ш(r), which are formed and implemented according to formulas (5.1 - 5.5) for the values of acceptable risks at a given hourly interval.
There are individual and social risks.
Individual risk characterizes the danger of a certain type for an individual.
Social (more precisely, group) is a risk for a group of people.
Social risk is the relationship between the frequency of events and the number of people affected (see figure).
The public's perception of risk and hazards is subjective. People react sharply to rare events accompanied by a large number of one-time victims. At the same time, frequent events that result in the death of a few or small groups of people do not cause such tension.
Every day 40...50 people die at work, and in the whole country more than 1000 people lose their lives from various dangers. But this information is less impressive than the death of 5-10 people in one accident or any conflict.
This needs to be kept in mind when considering the issue of acceptable risk.
Subjectivity in risk assessment confirms the need to search for techniques and methodologies that are free of this drawback.
According to experts, the use of risk as a hazard assessment is preferable to the use of trophytope indicators.
Basic provisions of risk theory.
In September 1990, the First World Congress on Safety as a scientific discipline was held in Cologne, under the motto “Life in Safety”. Specialists from different countries in their messages and reports they constantly used the concept of “risk”.
In Soviet technical literature on safety, this concept has not yet received appropriate recognition.
V. Marshall gives the following definition: risk - the frequency of occurrence of hazards.
Most general definition This is recognized: risk is a quantitative assessment of danger.
Quantitative assessment is the ratio of the number of certain adverse consequences to their possible number for a certain period. When defining a risk, it is necessary to indicate the class of consequences, i.e. answer the question: risk of what?
Formally, risk is frequency. But essentially there is a significant difference between these concepts, because In relation to safety problems, the possible number of adverse consequences must be discussed with a certain degree of convention.
Before moving on to consider other aspects of the risk problem, let us give examples. As an example, let us cite foreign data characterizing individual risk.
Individual risk of death per year due to various causes (based on the entire US population)
Road transport 3*10 -4
Falls 9*10 -5
Fire and burn 4*10 -5
Drowning 3*10 -5
Poisoning 2*10 -5
Firearms 1*10 -5
Machine equipment 1*10 -5
Water transport 9*10 -6
Air transport 9*10 -6
Falling objects 6*10 -6
Electric current 6*10 -6
Railway 4*10 -6
Lightning 5*10 -7
All others 4*10 -5
Total risk 6*10 -4
Nuclear energy (100 reactors) 2*10 -10