Classification of Environmental Hazards in the Workplace
Classification of Environmental Hazards
According to the way they interact with people, environmental hazards are classified as:
1. Chemical Hazards
These are represented by substances or chemicals that may be present in the workplace, depending on the production processes.
From the perspective of occupational hygiene, we can find them as gases or vapors and aerosols.
Causes of major diseases: asbestosis, systemic poisoning caused by the inhalation of dust or contact with organic chemical substances; respiratory tract irritation, visceral disease, hematopoietic system, CNS and others.
1.1. Gases
A collection of individual molecules with proper motion and movement in a group.
Individual movement is called kinetic motion. Group movement is called wind.
The sum of the forces exerted by individual molecules is called pressure.
- Static pressure: limited to a container
- Kinetic pressure release (wind)
Compared with aerosols, gases and vapors do not settle or agglomerate, but remain indefinitely in an intimate mixture with air, eventually separating on their own. According to their effect on the body, they are divided into irritant, asphyxiating, and anesthetic.
1.1.1. Irritating Gases and Vapors
These have the property of inducing pathophysiological inflammation of the tissues with which they come into contact. Examples include ammonia, hydrochloric acid, sulfuric acid, and formaldehyde.
1.1.2. Asphyxiating Gases and Vapors
These are those that block the process of oxygen exchange between blood and tissues. We distinguish between simple asphyxiants and chemical asphyxiants.
1.1.2.1. Simple Asphyxiants
These are different gases that can displace oxygen and cause asphyxiation. Examples include Nitrogen, Methane, Helium, Carbon Dioxide, and Propane.
1.1.2.2. Chemical Asphyxiants
These prevent oxygen uptake through a chemical action, even if there is oxygen in the air. For example, carbon monoxide and hydrogen cyanide. Their action is exercised at the cellular level.
1.1.3. Anesthetic Gases and Vapors
These include a wide variety of organic compounds, many of them widely used in industrial and domestic settings, especially as solvents or fuels. They exert their biological effects after being absorbed by the blood that circulates in the body, producing an anesthetic effect when inhaled in a certain amount, incorporated into the bloodstream and subsequently reaching the CNS.
1.2. Aerosols
These are finely divided solid or liquid particles dispersed in a gaseous medium. Depending on the characteristics of these particles, they are divided into:
1.2.1. Solid Aerosols
These are further classified as:
1.2.1.1. Powders
Particles mechanically generated by drilling, blasting, stone cutting, milling, grinding, polishing, and sieving.
1.2.1.2. Smokes
Aerosols formed by the condensation of vapors of substances that are solid. Metal fumes are the most common, including lead (lead poisoning), Zinc, Iron, Copper, and Tin.
Regarding particle size, it must be remembered that those smaller than 5 microns are important for occupational hygiene because larger dust particles settle quickly due to their weight and are not commonly inhaled. The human respiratory system is designed to retain particles larger than 5 microns, so smaller sizes pass directly to the deep airways (called respirable). In the industrial sector, particles are typically less than 2 microns and about 50% of them are between 0.5 and 0.7 microns.
Considerations:
- The respiratory tract is a system like an inverted tree with branches. At each intersection, the bends and air movement create opportunities for inertial impaction.
- The nose is a natural filter, but not very efficient for particles smaller than 10 microns.
- Particle size can determine how deep they penetrate before being deposited.
- The shape of the pollutant affects penetration and adsorption or absorption.
- Fibers (solid particles that are longer than three times their thickness) can penetrate very deeply, even deeper than a smaller particle (because of their arrow-like shape).
1.2.2. Liquid Aerosols
These are further classified as:
1.2.2.1. Sprays
Aerosols formed by the mechanical disruption of liquid substances. The most common processes are spray painting and general liquid dispersion (spray operation).
1.2.2.2. Mists
Aerosols formed by the condensation of vapors of substances normally found in liquid form.
2. Physical Hazards
The effects of physical agents are due to an energy exchange between the individual and the environment at a rate higher than the body can withstand, which could lead to an occupational disease. Among the most important are:
2.1. Radiant Energy
Radiation can be defined generally as a way of transmitting energy. This is effected by electromagnetic waves that differ only by the energy they possess.
Within this category are non-ionizing and ionizing radiation.
What is the importance of ionization to occupational hygiene?
- Our bodies are filled with ions. We cannot live without them.
- The problem is the ionization of atoms in molecules that should not be ionized.
- The electrons of ionized atoms seek to return to normal.
- Ionization results in chemical reactions that should not occur.
Direct action: ionization and excitation lead to changes in the structural integrity of DNA, enzymatic changes, and so on, which can lead to alterations of vital functions of cells, such as protein synthesis and the inheritance of daughter cells, among others. This may lead to irreparable damage or even cell death.
Indirect action: Chemical changes occurring in the water molecule, as the main element in the composition of the overall structure of the body, mainly originate hydroxyl (OH) groups, which are major oxidizing agents that are toxic to cells and tissue in general. These elements are also known as free radicals.
Stable tissue: These are radioresistant. At high doses, cell death occurs. At smaller doses (low), only functional changes occur. Example: CNS tissue.
Proliferative tissues: These are very radiosensitive due to cell division. In these tissues, the effects of radiation are higher in childhood and youth compared to adulthood, as mentioned earlier.
Replacement tissue: These have a spare compartment where cell division and maturation are ongoing, along with a functional sector. They are the most radiosensitive. Example: Bone marrow.
Background Radiation Protection in Chile
- Personnel occupationally exposed: 8,000
- Total occupationally exposed personnel in three categories: 15,000
- Number of medical and dental X-ray equipment: 6,000
- Average number of imaging tests per year: 6-7,000,000
- Estimated overall rate of tests: 50 per 100 inhabitants.
Source: ISP. Chile 2005
2.1.2. Non-Ionizing Radiation
This group includes infrared radiation, ultraviolet radiation, and microwaves, among others.
2.1.2.1. Infrared Radiation
Comes from incandescent sources and can affect metallurgists, smelters, glass blowers, among others. It can cause skin damage by increasing the temperature of the tissues; injury to the cornea, iris, retina, and lens. Glass blower’s cataract.
2.1.2.2. Ultraviolet (UV) Radiation
Not visible to the naked eye. Produced naturally by the sun and artificially by welding arcs.
2.1.2.3. Microwave Radiation
Higher energy than the previous two. Used in satellite transmission, household ovens.
According to its environment, it can be classified into:
- Public spaces: power lines, radio, TV, telecommunication systems, mobile telephone systems, radar systems.
- Residential areas: local power lines, home electrical wiring, appliances.
- Occupational areas: transmission lines, generating stations and substations, power stations, induction heaters, nuclear magnetic resonance, microwave ovens, diathermy therapy, radio antennas, military radar.
2.2. Abnormal Temperatures
Our body maintains a heat balance (37°C peripheral, 38°C deep), which can be altered when it suffers:
2.2.1. Increased Temperature
As experienced by workers in foundries and kilns. The body’s reaction includes heat cramps, heat exhaustion, and heatstroke.
2.2.2. Decreased Temperature
Present in refrigerators and cold rooms in general. The cold causes varying degrees of difficulty in blood circulation, producing effects ranging from rashes to death by freezing (hypoxia).
2.3. Noise and its Impact
Noise is one of the most common problems in the working environment in our country (sensorineural hearing loss). Functionally, noise is unwanted sound (subjective) that is annoying or harmful.
2.3.1. Noise Control Measures
2.3.1.1. Control of Noise at the Source
- Replacement of equipment or processes
- Intervention in equipment and/or processes without altering their characteristics
- Changing work processes
- Reducing noise-generating forces
2.3.1.2. Control in the Propagation Medium
- Provision and planning of noisy equipment
- Acoustic conditioning of inner boundary surfaces of enclosures (absorption, reverberation time)
- Sound isolation booths, enclosures, barriers
- Sound field control and pathways (silencers or filters, active control)
2.3.1.3. Control at the Receiver (Hearing Protection)
3. Biological Hazards
3.1. Viruses
Viruses are macromolecular structures, without movement or their own metabolism, that can only multiply inside living cells, making them obligate parasites. For this reason, many biologists debate whether they should be considered living organisms or a link between living and non-living matter.
Viral Hepatitis B: Liver inflammation, jaundice, dark urine. From mild to lethal (1%).
Transmission Mode: Percutaneous exposure (intravenous, intramuscular, subcutaneous, and intradermal)
3.2. Bacteria
Bacteria are unicellular prokaryotic microorganisms. They may group together to form colonies. Their main form of reproduction is asexual, by binary fission, and they proliferate rapidly when the environment is favorable.
According to their shape, bacteria can be classified into:
3.2.1. Cocci
Spherical shape. Can be grouped as diplococci (in pairs), streptococci (in chains), staphylococci (clusters), etc.
3.2.2. Bacilli
Elongated or rod-shaped.
3.2.3. Vibrio
Comma-shaped.
3.2.4. Spirillum
Coil or corkscrew-shaped.