Health Hazards (Continued)
This module will continue the discussion about the various health hazards to which construction workers are exposed. These topics will help you better understand and be able to react to
occupational health hazards in construction. The topics we will discuss in this module include:
- excessive noise
- ionizing and non-ionizing radiation
- exposure to asbestos
Every year, approximately 30 million people in the United States are occupationally exposed to hazardous noise. Employers must have a hearing conservation program whenever employee
noise exposures equal or exceed an eight-hour time-weighted average sound level (TWA) of 85 A-weighted decibels (dBA). A decibel is an expression of the relative loudness of sound in
air as perceived by the human ear.
When employees are exposed to sound levels exceeding those listed in the table to the right, administrative or engineering controls must be used. For instance, if employees are exposed
to an average of 90 dBA over an 8-hour workday, then hearing protection controls must be used.
To reduce exposure to excessive noise in the construction industry, take the following precautions:
- Reduce the time workers spend in noisy areas.
- Rotate two or more workers so that each is exposed to noise less than 85 dBA, averaged over an eight-hour day.
- Shut down noisy equipment when it’s not needed.
- Maintain equipment so it runs smoothly and quietly.
- Ensure workers know how to perform their tasks and operate equipment at safe noise levels.
- Use earplugs and earmuffs. To be effective, they must totally block the ear canal with an airtight seal. An improperly fitted, dirty, or worn-out plug will not seal and can irritate the ear canal.
Radiation: Ionizing and Non-Ionizing
Sources of Radiation Exposure
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Radiation sources are found in a wide range of occupational settings. If radiation is not properly controlled it can be potentially hazardous to the health of workers.
- All forms of ionizing radiation have sufficient energy to ionize atoms that may destabilize molecules within cells and lead to tissue damage.
- Non-ionizing radiation is essential to life, but excessive exposures will cause tissue damage.
The Electromagnetic Spectrum
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Ionizing radiation is energy in the form of waves or particles that has enough force to remove electrons from atoms and emit particles and high-energy waves (radioactive decay).
Ionizing radiation sources may be found during demolition and construction activities such as tunneling, highway and road construction. These radiation sources can pose a considerable
health risk to affected workers if not properly controlled.
Workers in construction are primarily exposed to natural radiation from the sun, cosmic rays, and naturally-occurring radioactive elements, primarily uranium, thorium, and potassium,
and their radioactive decay products, found in the earth’s crust. These elements emit alpha particles, beta particles, and gamma rays which are discussed below:
Alpha Particles: Alpha particles, positively charge particles emitted in the radioactive decay of the heaviest radioactive elements.
The primary source of exposure for construction workers is radon, which naturally occurs in rock and soil. Radon can accumulate in crawlspaces, mines, tunnels, basements, and other
poorly ventilated areas.
Beta Particles: Beta particles are fast moving electrons emitted from the nucleus during radioactive decay. They travel considerable distances in air but can be reduced or stopped by
a layer of clothing, but some beta particles are capable of penetrating the skin and causing radiation damage, such as skin burns.
Gamma Rays and X-Rays: Gamma rays are photons that can pass through several feet of concrete or a few inches of lead. Gamma rays can pass through the entire body. X-rays are high-energy
photons produced by the interaction of charged particles with matter, and a few millimeters of lead can stop x-rays. Because of their many uses, x-rays are the single largest source
of man-made radiation exposure.
Non-ionizing radiation is composed of oscillating electric and magnetic found in a wide range of occupational settings. These fields can pose a considerable health risk to exposed
workers if not properly controlled. Non-ionizing radiation includes each of the following:
- Extremely Low Frequency Radiation (ELF): Extremely Low Frequency (ELF) radiation at 60 HZ is produced by power lines, electrical wiring, and electrical equipment.
- Radiofrequency (RF) and Microwave Radiation (MW): Microwave radiation is absorbed near the skin, while RF radiation may be absorbed throughout the body. At high enough intensities, both will
damage tissue through heating.
- Infrared Radiation (IR): The skin and eyes absorb infrared radiation (IR) as heat. Workers normally notice excessive exposure through heat sensation and pain. Sources of IR radiation include
furnaces, heat lamps, and IR lasers.
- Visible Light Radiation: The different visible frequencies of the electromagnetic (EM) spectrum are "seen" by our eyes as different colors. Good lighting is conducive to increased production
and may help prevent incidents related to poor lighting conditions. Excessive visible radiation can damage the eyes and skin.
- Ultraviolet Radiation (UV): Ultraviolet radiation (UV) has a high photon energy range and is particularly hazardous because there are usually no immediate symptoms of excessive exposure.
Sources of UV radiation include the sun, black lights, welding arcs, and UV lasers.
- Laser Hazards: Lasers typically emit optical (UV, visible light, IR) radiations and are primarily an eye and skin hazard. Common lasers include CO2 IR laser, helium-neon, neodymium YAG, and
ruby visible lasers, and the Nitrogen UV laser.
General safety precautions while using lasers include:
- Wear appropriate protective eyewear.
- Use minimum power/energy required for the project.
- Reduce laser output with shutters/attenuators.
- Terminate laser beam with beam trap.
- Use diffuse reflective screens, remote viewing systems, etc., during alignments.
- Remove unnecessary objects from the vicinity of the laser.
- Keep the beam path away from eye level (sitting or standing).
- Don’t put your body parts (especially the eyes) in the beam.
The following three strategies are effective in reducing excessive exposure to ionizing and non-ionizing radiation:
- Time: The amount of radiation exposure increases and decreases with the time workers spend near the source of radiation.
- Distance: The further workers are from a radiation source, the less their exposure.
- Shielding: The greater the shielding around the radiation source, the smaller the exposure.
Exposure to Asbestos
Asbestos is the generic term for a group of naturally occurring fibrous minerals with high tensile strength, flexibility, and resistance to thermal, chemical, and electrical conditions.
Asbestos is well recognized as a health hazard and its use is now highly regulated by both OSHA and EPA. Asbestos fibers associated with these health risks are too small to be
seen with the naked eye. Health risks commonly associated with exposure to asbestos include:
- Asbestosis – a condition in which the lungs become scarred with fibrous tissue, making breathing more and more difficult, often requiring the victim to use oxygen.
- Cancer – cancer of the lungs is the most common cancer associated with exposure. Other areas may become cancerous including the throat, gastrointestinal tract, and kidneys.
- Mesothelioma - a rare, often fatal cancer, usually occurring in the chest cavity.
Some examples of products that contain asbestos include:
- floor covering and adhesives
- exterior siding
- ceiling tiles
- pipe insulation
- floor tiles
- roof flashing
- plaster walls
- roof shingles
- wallboard joint compound
Workers in construction may be exposed to asbestos during the following activities:
- demolishing or salvaging structures where asbestos is present
- removing or encapsulating asbestos-containing materials
- constructing, altering, repairing, maintaining, or renovating asbestos-containing structures or substrates
- installing asbestos-containing products
- cleaning up asbestos spills/emergencies
- transporting, disposing of, storing, containing, and housekeeping involving asbestos or asbestos-containing products on a construction site
OSHA has established a classification system for asbestos construction work that spells out mandatory, simple, technological work practices that employers must follow to
reduce worker exposures. Under this system, the following four classes of construction work are matched with increasingly stringent control requirements:
Class I asbestos work is the most potentially hazardous class of asbestos jobs. This work involves the removal of asbestos-containing thermal system insulation and sprayed-on
or troweled-on surfacing materials.
Class II work includes the removal of other types of ACM that are not thermal system insulation, such as resilient flooring and roofing materials. Examples of Class II work
include removal of asbestos-containing floor or ceiling tiles, siding, roofing, or transite panels.
Class III asbestos work includes repair and maintenance operations where ACM or presumed ACM (PACM) are disturbed.
Class IV work includes custodial activities where employees clean up asbestos-containing waste and debris produced by construction, maintenance, or repair activities. This work
involves cleaning dust-contaminated surfaces, vacuuming contaminated carpets, mopping floors, and cleaning up ACM or PACM from thermal system insulation or surfacing material.
All Class I, II, and III asbestos work must be done within regulated areas. The following are required for all regulated areas:
- Only authorized personnel may enter.
- The designated competent person supervises all asbestos work performed in the area. Employers must mark the regulated area in any manner that minimizes the number of persons within the area and protects persons outside the area from exposure to airborne asbestos.
- Critical barriers or negative-pressure enclosures may mark the regulated area.
- Posted warning signs marking the area must be easily readable and understandable. The signs must bear the following information:
- Employers must supply a respirator to each person entering regulated areas.
- Employees must not eat, drink, smoke, chew tobacco or gum, or apply cosmetics in regulated areas.
The employer performing work in a regulated area must inform other employers on site of the following:
- the nature of the work
- regulated area requirements
- measures taken to protect on-site employees
For all covered work, use the following control methods to comply with the PEL, STEL, and DEQ/LRAPA rules:
- Ensure local exhaust ventilation is equipped with HEPA-filter dust collection systems.
- Enclose or isolate processes producing asbestos dust.
- Ventilate regulated areas to move contaminated air away from the employees’ breathing zone and toward a filtration or collection device equipped with a HEPA filter.
- Use engineering and work practice controls to reduce exposure to the lowest possible levels, supplemented by respirators to reach the PEL or STEL or lower.
- File a notification with DEQ/LRAPA.
- Use waste shipment form for waste transport.
For all work operations, use the following engineering controls and work practices for all operations, regardless of exposure levels:
Asbestos and lead paint cleanup is a big concern in this photo.
- Use vacuum cleaners equipped with HEPA filters to collect all asbestos-containing or presumed asbestos-containing debris and dust.
- Use wet methods or wetting agents to control employee exposures, except when wetting methods would cause electrical hazards, equipment malfunction, slipping hazards, or other hazards.
- Deactivate electrical circuits, if not provided with ground-fault circuit interrupters (GFCI).
- Promptly clean up and dispose of asbestos-contaminated waste and debris in leak-tight containers.
Prohibited work practices and engineering controls. Comply with these work practices and engineering control prohibitions for all asbestos-related work or work that disturbs asbestos or presumed
asbestos-containing materials, regardless of measured exposure levels or the results of initial exposure assessments:
- Do not use high-speed abrasive disc saws unless they are equipped with a point-of-cut ventilator or enclosed with HEPA-filtered exhaust air.
- Do not use compressed air to remove asbestos or asbestos-containing materials unless the compressed air is used with an enclosed ventilation system.
- Do not dry sweep, shovel, or conduct any other dry cleanup of dust and debris.
- Do not rotate employees to reduce exposure.
- Do not allow the accumulation of friable asbestos materials or asbestos containing waste.
- Do not dispose materials at an unauthorized site.
OSHA will soon publish the new Confined Spaces in Construction Standard, CFR 29 1926 Subpart AA, 1926.1200. This section is a brief overview to familiarize you with some of the requirements of
this new standard.
A confined space that is subject to a hazard on a construction site must be classified. The classification determines what accident-prevention and -protection requirements apply to that space.
There are four classifications of confined spaces on a construction site:
- Isolated-Hazard Confined Space (IHCS)
- Controlled-Atmosphere Confined Space (CACS)
- Permit-Required Confined Space (PRCS)
- Continuous System-Permit-Required Confined Space (CS-PRCS)
The employer has the option of selecting any of these classifications, as long as the employer meets the applicable requirements for the classification selected. The one exception is that a
space with the characteristics of a CS-PRCS cannot be given a different classification.
Contractors must follow step-by-step entry of a Construction Site Permit-Required Confined Space (CS-PRCS) because, with the hazards as yet undetermined, taking these precautions will ensure
the safety of the employees.
Confined Space Hazards
Below are typical confined space hazards to which construction workers may be exposed:
- biological hazards
- pits (condenser, elevator)
- containment cavities
- electrical shock
- electrical transformers
- enclosed beams
- explosive or toxic atmospheres
- heat sinks
- materials falling into the space
- manholes (sewer, electrical, etc.)
- pipe assemblies
- purging agents
- oxygen deficiency
- septic tanks
- tanks (fuel, chemical, water)
- ventilation ducts
- wind turbines, towers, blades
Precautions and Best Practices
Prior to entering a potentially dangerous confined space, the following procedures should be followed:
- The controlling contractor should determine if there are any atmospheric hazards in the confined space using standard atmospheric testing and monitoring equipment. All testing of the internal
atmosphere of the confined space must be done without use of mechanical ventilation or changes to the space's natural ventilation. This is to ensure that the natural atmospheric conditions
within the space are assessed for hazards that may affect those employees working in the space.
- The controlling contractor should coordinate entry with all contractors who have workers entering a confined space.
- In Confined Spaces with Hazards Isolated (CSHI), the controlling contractor should isolate or eliminate all physical and atmospheric hazards in the confined space.
- In Controlled-Atmosphere Permit-Required Confined Spaces (CA-PRCS), continuously monitor the atmosphere within the confined space unless periodic monitoring is proven sufficient.
- In Permit-Required Confined Spaces (PRCS), every confined space supervisor must monitor PRCS conditions during entry.
- Maintain a written plan unless a copy of the OSHA standard is located on the worksite.
- Ensure early-warning requirements for up-stream sewer-type spaces are maintained.
OSHAcademy’s partner, HSE Press, recently published an article with more specific information on the new
Confined Space in Construction Standard.
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