Assessing Occupational Risk: A Classification of Harmful Factors in the Production Environment and Labor Process

The issue of classification of harmful and/or hazardous production factors to determine occupational hazards is very relevant. However, there is still no single reference book or manual in the world about various occupational hazards for specific professions due to their huge diversity [5].

One of the first attempts to create a practical list of dangers was the work of Brandt [6] "Industrial Health Engineering".

The author of this book presented a selection of about 1300 different professions with an indication of the relevant occupational risks for each profession. Among the listed hazards, the majority were chemically dangerous.

In the future, systematic work on this issue was not carried out, except for some partial lists relating to limited aspects of occupational risks [5].

In 1964, in Haddon's book "Accident Research: Methods and Approaches" [7], an attempt was made to classify various types of accidents. In 1973, the book by Stellman and Daum [8] "Work is dangerous for your health" presented a table of health hazards by profession ("table of health hazards listed by occupation").

The next attempts at classifications in this area were a set of incomplete lists of "potential occupational exposures" published in 1977 in the monograph of the National Institute of Occupational Safety and Health (NIOSH) "Occupational Diseases: a guide to their Recognition" [9], as well as a list of about 1,000 different potential health hazards that may exist approximately in 2000 different professions, which was compiled in 1973 by the Faculty of Medicine of Tel Aviv University [5].

However, all the listed projects cannot reflect the full extent of the hazards present at enterprises, since they are partial in nature, do not cover the entire field of labor protection, and the list of professions is unstable and varies depending on historical and technological progress.

In this regard, it became necessary and an attempt was made to create a unified classification of harmful and/or hazardous production factors, based on domestic and international experience for assessing the occupational risk of employees, on the basis of which a more complete and reliable identification of hazards in the workplace is possible.

To this end, the scientific and methodological literature in the field of occupational safety, regulatory documents, interstate standards, scientific works, and developments of domestic and foreign scientists were analyzed [10-16].

The following main groups of risks associated with the impact of factors of the production environment and the labor process on the employee's body have been identified - physical nature, chemical nature, biological nature, mechanical nature, psychophysiological nature, as well as the impact of general industrial pollution.

Thus, in the "Systematization of occupational hazards by Profession" of the ILO [14], the following classification of dangerous and harmful production factors is presented:

1. Hazards (accident hazard; mechanical and general; chemical accidents; electrical accidents; fires and chemical explosions; radiation accidents).

2. Physical hazards (ionizing radiation; non-ionizing radiation; vibration, noise; exposure to weather conditions).

3. Chemical hazard (direct/immediate effects - irritation of mucous membranes, eyes, and respiratory organs; effects on the nervous system; gastrointestinal disorders; skin effects; asphyxia; delayed, chronic or long-term effects - chronic systemic poisoning; skin, eye, inhalation effects;effects on the reproductive system; carcinogenesis and mutagenesis.

4. Biological hazards (microorganisms and their toxic products; poisonous and allergenic plants; animal exposure).

5. Ergonomic and social factors.

In the technical regulations of the Customs Union "On the safety of personal protective equipment" (TR CU 019/2011) personal protective equipment is classified depending on the protective properties [15]:

- from mechanical influences (from abrasion, punctures, cuts, vibration, noise, blows to different parts of the body, possible capture by moving parts of mechanisms; from general industrial pollution; from water and solutions of non-toxic substances; from non-toxic dust; from sliding on surfaces);

- from chemical factors (from toxic substances; from acid solutions; from alkalis; from organic solvents, including lacquers and paints based on them; from oil, petroleum products, oils, and fats);

- from biological factors (from harmful microorganisms, insects, and arachnids);

- from radiation factors (from radioactive contamination and ionizing radiation);

- from elevated and (or) lowered temperatures;

- from thermal risks of electric arc, non-ionizing radiation, electric shock, and electric electromagnetic fields, as well as from the effects of static electricity.

In the practical manual of Murtonen [16] "Risk assessment in the workplace" (Finnish experience), the following are highlighted: physical hazard factors, accident risk factors, ergonomics, chemical and biological risk factors, as well as psychological overload, which echoes the above-mentioned grouping of factors.

The analysis of the mentioned classifications allowed us to conclude that the most correct grouping of the main factors is the grouping according to the Nomenclature of personal protective equipment, depending on harmful production factors and the degree of their impact [13]: On factors of physical, chemical, biological, mechanical, psychophysiological nature, as well as the effects of general industrial pollution. In this work, for the first time, the authors proposed personal protective equipment depending on a wide range of harmful and/or dangerous factors of the production environment and the labor process, as well as the degree of their impact on the employee's body, indicating the norms, terms of wear and appropriate standards for this protective equipment.

The most numerous group of factors are physical factors. So, in the Recommendations for the classification, detection, recognition, and description of hazards (Order of the Ministry of Labor of the Russian Federation of January 31, 2022 No. 36), physical hazards include electrical, radiation hazards, noise, vibration, fire, as well as mechanical (moving parts of machines and equipment) and gravitational (falling people/objects from a height) hazards [17].

The US National Association of Safety Professionals (NASP) classifies physical hazards as loud noises, extreme pressures, magnetic fields, radiation, fire, poor lighting, unsafe equipment, misused equipment, walkway obstructions, slippery floors, etc. [18].

The largest category of physical factors is vibroacoustic, which encompasses various harmful elements. Industrial noise is the most prevalent factor, characterized by the random combination of sounds with different frequencies and intensities that arise from mechanical vibrations in solid, liquid, and gaseous media. Numerous studies have been conducted to assess the impact of noise on human health and productivity [19-22]. Noise can be classified based on frequency response (low-, medium-, and high-frequency), spectrum nature (broadband or tonal), temporal characteristics (constant or non-constant), and the type of source (mechanical, aerodynamic, electromagnetic, hydrodynamic) [19].

Vibration is another common hazardous factor in production environments. Over the past decade, therapists specializing in occupational rehabilitation have observed a significant increase in the prevalence of cumulative traumatic vibration disorders [23]. According to Semenov [24], industrial vibration can be categorized based on transmission method (general or local), direction (vertical or horizontal), exposure period (temporary or constant), frequency (low, medium, or high), and spectral nature (narrowband or broadband).

The group of vibroacoustic factors also includes infrasound and ultrasound. In infrasound, sanitary standards [25] distinguish between spectrum nature (broadband or tonal) and temporal characteristics (constant or non-constant). The sound pressure level of constant infrasound varies no more than 2 times (6 dB) during the observation period, while non-constant infrasound changes by at least 2 times (6 dB) when measured using a "linear" sound level meter scale with a "slow" time characteristic.

Ultrasound is categorized based on the method of ultrasonic vibration propagation. Hygienic classification [26] distinguishes between contact and airborne ultrasound. Ultrasonic vibrations are further categorized based on the type of source (manual or stationary), spectral characteristics (low-frequency: 16-63 kHz, mid-frequency: 125-250 kHz, high-frequency: 1.0-31.5 MHz), mode of generation (constant or pulsed), and method of radiation (ultrasound sources with magnetostrictive or piezoelectric generators).

Noise and vibration in combination with the fibrogenic effect of dust and high loads cause the greatest risk of occupational diseases [27-30].

The next, no less important group of harmful production factors are radiation (optical (non-ionizing), ionizing, electromagnetic fields, as well as lighting). According to OSHA [31], non-ionizing radiation occurs in a wide variety of occupational settings and can pose a significant health risk to potentially exposed workers. Non-ionizing radiation includes:

- extremely low-frequency radiation (ELF) - at a frequency of 60 Hz is produced by power lines, electrical wiring, and electrical equipment;

- radio frequency and microwave radiation - damage tissue as a result of heating;

- infrared radiation (IR) - sources are stoves, heat lamps, and IR lasers, excessive exposure is felt in the form of heat and pain;

- visible light radiation - excessive visible radiation can damage the eyes and skin;

- ultraviolet radiation (UV) - has a wide range of photon energies; sources are the sun, black light, welding arcs, and UV lasers;

- laser radiation - includes an IR laser on CO₂; helium-neon, neodymium YAG and ruby lasers in the visible range, as well as a nitrogen UV laser; which are hazardous to eyes and skin.

Sources of ionizing radiation include radioactive materials and radiation-generating machines [32]. A number of works are devoted to the harmful effect of ionizing radiation on the body of workers, including [33-35]. The main types of ionizing radiation are alpha, beta, gamma, and X-rays. This group of radiation also includes electrically charged air particles - air ions [12, 36]. When interacting with a person, ionizing radiation can damage living cells in the human body.

The next group of radiations consists of non-ionizing electromagnetic fields [12], which include the geomagnetic field (weakening); electrostatic field; permanent magnetic field (including hypogeomagnetic); electric fields of industrial frequency (50 Hz); magnetic fields of industrial frequency (50 Hz); electromagnetic fields at the workplace of a PC user; electromagnetic radiation of the radio frequency range; broadband electromagnetic pulse. Electromagnetic fields cause chromosomal aberrations in lymphocytes and other cardiovascular effects in the body of workers [37-39].

Illumination is a significant factor in the production environment. The evaluation of light environment parameters for both natural and artificial lighting is conducted based on specific criteria [12]. Natural lighting is assessed using the coefficient of natural light, while artificial lighting is evaluated using various indicators such as illuminance, direct brilliance, pulsation coefficient of illumination, and other standardized measures of illumination. When assessing working conditions in terms of illumination, consideration is given to the ability to compensate for insufficient or absent natural light by creating favorable conditions for artificial lighting. Additionally, if necessary, measures can be taken to address inadequate ultraviolet radiation.

Electrical accidents are very common in the workplace and are caused by unprotected exposure to high-voltage electrical outlets. According to the International Electrical Safety Foundation, electrical hazards cause over 300 deaths and 4 injuries in American workplaces each year [40].

Electrical burns, electrical fires, and electric shocks are the 3 main types of electrical accidents. Electrical shock occurs when body contact with electricity causes current to flow through your body, and in severe cases, this can lead to heart or respiratory failure.

In many cases, electrical burns are the result of electrical shock, and they can be internal or external. Electrical fires occur when bare wiring or broken circuits come into contact with flammable materials in the workplace, such as cotton and wood shavings.

While it is crucial to address the electrical hazard of direct contact, there is another electrical hazard associated with the release of intense radiant and convective energy during an electrical arc flash. It's important to note that a person doesn't have to physically touch a live conductor or be part of an electrical circuit to be harmed by an arc flash. Even when positioned just a few feet away from energized conductors or equipment, individuals can sustain severe injuries due to the high levels of heat energy emitted by the electric arc [41]. In the United States alone, it is estimated that 5 to 10 arc flash explosions occur in electrical equipment each day. In the mining industry, non-contact electric arcs account for the largest single category of electrical injuries [42].

Specially created electric arcs, which involve an electric charge located between electrodes and emit a significant amount of energy, are commonly utilized as a heat source in welding processes [43, 44]. The welding arc has a maximum temperature of approximately +7,000℃. This level of heat is employed in the metalworking of materials that require temperatures exceeding +3,000℃ for melting. When discussing the characteristics of this electric charge, it is important to understand that the welding arc functions as a conductor formed by ionized gas. The arc comprises multiple zones that release substantial thermal energy as current passes through them. The ignition of the arc establishes a galvanic circuit involving the anode, cathode, and ionized gas. This process involves the use of two electrodes. The flow of current generates the heating of the arc, and the emission of light from it is attributed to the presence of photon radiation.

Welding poses several hazards to both those performing the activity and those around them. The main types of hazards in the performance of welding work are exposure to smoke and gases; fires and explosions; electric shock; noise hazards; exposure to UV and IR radiation, as well as burns [45].

The next category of hazardous physical factors involves the risk of fire or explosion. The consequences of workplace fires or explosions can be severe, leading to loss of life, injuries, and significant damage to property and the environment. Flammable substances, including dust, liquids, and gases, pose a significant danger in this regard.

Dust from various common materials such as coal, wood, and flour, among others, has the potential to create an explosive atmosphere. Liquids such as gasoline, solvents, and certain chemicals release vapors that can ignite or explode when mixed with air. Gases, such as LPG, hydrogen, or other flammable industrial gases, are typically stored under pressure in cylinders and can easily ignite or explode if there are any fugitive releases.

Open flames or sparks, including those generated by static charges resulting from friction, can serve as ignition sources in these situations.

It is crucial to take appropriate precautions and preventive measures to minimize the risk of fire or explosion in the workplace [46, 47].

The smoke released during fires is also a great danger. Inhalation of smoke can cause problems in several ways: suffocation with carbon monoxide; poisoning of the body with toxic substances; damage to the windpipe, respiratory tract, and/or lungs with toxic chemicals, as well as burning of the mouth and throat with hot gases [48].

An important group of physical factors considered in this article are the climate and microclimate in the open area and indoors. According to the previous studies, the indicators characterizing the microclimate in industrial premises are air temperature; surface temperature, relative humidity; air velocity; the intensity of thermal irradiation [12, 49]. Microclimate indicators should ensure the preservation of a person's thermal balance with the environment and the maintenance of an optimal or permissible thermal state of the body. Hygienic requirements for microclimate indicators are established for workplaces on industrial premises. An important indicator of the microclimate is thermal radiation. It is one of the harmful production factors affecting the labor process [50]. The hyperbaric environment is an environment with high atmospheric pressure, the characteristic factor which significantly affects the human body during professional activity [51].

The aerosol composition of the air in the presence of aerosols of predominantly fibrogenic action (PFA) is also a common harmful factor of production. Inhalation of these aerosols by an employee is the cause of a number of occupational respiratory diseases (dust bronchitis, pneumoconiosis, lung cancer, etc.). All PFA are divided into high-, moderate- and weakly fibrogenic, which is reflected in hygienic rationing, taken into account in hygienic control and classification of working conditions according to indicators of harmfulness [47, 52-54].

The next large group consists of production factors of chemical nature, which are divided by toxicity, the effects, and ways of penetration of harmful substances into the human body, as well as by physical action [10, 12, 14].

Within the framework of the Globally Internationally Harmonized System (GHS) hazard Classification of chemical products, chemicals are classified according to their physical properties (explosion hazard, flammability), toxicological health hazards, and environmental hazards. Toxicological hazards are acute toxicity, irritation or corrosion activity, sensitization, carcinogenicity, mutagenicity, reproductive toxicity, and chronic or repeated dose toxicity [55]. GHS is also incorporated into U.S. regulations through a Proposed Rulemaking Notice issued in September 2009 by the Occupational Safety and Health Administration (OSHA) [56]. Any chemical or physical property of a material can be associated with information within a single molecule and its structure, thereby developing prediction models such as QSAR and QSPR [57-61].

Considerable attention in scientific literature and regulatory documents is dedicated to biological hazards [12, 14, 62-68]. According to the study in ref. [12], hazardous biological factors encompass microorganisms involved in production, living cells and spores present in bacterial preparations, and pathogenic microorganisms that act as agents of infectious diseases. The pathogenicity groups for these factors are outlined in sanitary and epidemiological rules and regulations [62]. The Decree of the Polish Minister of Health on biological agents harmful to health [63] provides a classification and list of harmful biological agents, as well as a roster of occupations that expose workers to such agents. Harmful biological factors can result in infections, allergies, and poisoning, and include cellular microbes (including genetically modified organisms), cell-free replicating or genetic material-transmitting units (including genetically modified ones), internal human parasites, and cell cultures.

The list of occupations exposing workers to biological agents includes employment in medical institutions, clinical, veterinary, or diagnostic laboratories, waste management enterprises, wastewater treatment facilities, food production enterprises, agricultural settings, and any work involving contact with animals or animal products. The concept of harmful biological factors in the production environment, "Biological hazards when working in contact with soil, livestock or crops," encompasses microorganisms and macroorganisms, as well as substances they produce that adversely affect the human body [61]. These factors include infectious disease-causing agents such as viruses, bacteria, fungi, or protozoa; allergens and toxins produced by plants, including crop and animal poisons; and carcinogens associated, for example, with wood dust or mold fungi.

The next group of factors are industrial hazards - a fall in the work area, accidents on transport and exposure to production equipment, or mechanical hazards [51]. Mechanical hazards are a very important, unique group of physical hazards generated by the workflow, the consequences of which are instantaneous. because of the combination of different aspects. People have had to contend with dangers since the advent of modern industrial civilization. The level of intensity of the negative consequences of hazards increases with the speed, mass, etc. characteristics of the working equipment.

In the Hungarian course on the promotion of occupational safety [69], the most common sources of mechanical hazards are work tools, transport, handling, movement of tools (eg forklifts, cranes), respectively. Movement of products and exposure to dyes, adhesives, oily and other substances (or labor products) [70].

Classification of production factors for occupational risk is presented in Table 1.