Course 151 - Biological Health Hazards in Construction

Biological Risk Factors

In construction, change is constant.

Risk Factors in Construction

Construction work is dynamic, diverse, and constantly changing. This leads to a great challenge in protecting the health and safety of construction workers. Workers are at risk of exposure to many different types of hazards that can result in physical injury, illness, disability, or even death.

Here's a list of factors that increase the health and safety risk of workers while working on construction sites:

  • Constantly changing job site environments and conditions affect the health and safety of workers. Constant change is the most common factor causing injuries and illnesses in construction.
  • Multiple contractors and subcontractors may create hazards unknown to others due to poor communication and coordination.
  • High turnover and unskilled laborers result in a lack of awareness of hazards.
  • Lack of education and training on hazards and safe work practices.
  • Diversity of work activities that happen simultaneously quickly create new hazards.
  • Exposures to health hazards, both from their own work as well as from nearby activities.

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1. What is the most common factor causing injuries and illnesses on construction worksites?

a. Extreme temperatures
b. Multiple contractors
c. Constant change
d. High turnover

Exposure to Biological Hazards

Exposure to biological hazards occurs during demolition.

Exposure to biological hazards may occur during demolition, renovation, sewer work, work on air handling systems, or other construction work from contact with contaminated or disease-carrying materials, such as:

  • soil
  • water
  • insects (mosquitoes, ticks)
  • bird or bat droppings
  • animals
  • structures

The most common biological health hazards in the workplace are found:

  • while working in health care facilities
  • where there is an accumulation of animal waste and the presence of rodents, insects and birds
  • during demolition and remodeling of old structures and buildings where there is likely the presence of mold
  • when removing plants, trees and other foliage during landscaping and clearing operations

2. Which of the following construction activities is most likely a common source of biological hazards?

a. Working in new residential construction
b. During work on bridges over water
c. During demolition of old structures
d. Working in newly constructed office areas

Fungi (Mold) Hazards

Example of black mold in walls.

Fungi (mold) are found everywhere, both indoors and outdoors, all year round. The terms fungi and mold are often used interchangeably, but mold is actually a type of fungi. There are many thousands of species of mold and most, if not all, of the mold found indoors comes from outdoor sources.

Mold seems likely to grow and become a problem only when there is water damage, high humidity, or dampness. Molds are organized into three groups according to human responses:

  • allergenic
  • pathogenic
  • toxigenic

We will take a closer look at each of these types of molds in the next tab.

3. In which condition are molds not likely to grow and become a problem?

a. In areas of high humidity
b. In areas of low humidity
c. In structures with water damage
d. In damp locations

Next Section

Molds Effect on the Body

Molds produce and release millions of spores small enough to be airborne. They can also produce toxic agents known as mycotoxins. Spores and mycotoxins can have negative effects on human health. The most common route of entry into the body is through inhalation; mold has a characteristic smell - if you smell mold, you could be inhaling mold. Mold is generally visible; however, some of the most toxic mold spores are small enough to be considered respirable [less than 10 micrometers (10 μm) in diameter].

Allergenic Molds

Mold Exposure in the Work Environment - IAQ Network

Allergenic molds do not usually produce life-threatening health effects and are most likely to affect those who are already allergic or asthmatic. The human system responses to allergenic molds tend to be relatively mild, depending on individual sensitivities, typically producing scratchy throats, eye and nose irritations, and rashes.

Pathogenic Molds

Pathogenic molds usually produce some type of infection. They can cause serious health effects in persons with suppressed immune systems. Healthy people can usually resist infection by these organisms regardless of dose. In some cases, high exposure may cause hypersensitivity pneumonitis (an acute response to exposure to an organism).

Toxigenic Molds

Mycotoxins can cause serious health effects in almost anybody. These agents have toxic effects ranging from short-term irritation to immuno-suppression and possibly cancer. Therefore, when toxigenic molds are found, further evaluation is recommended.

4. Which of the following molds can possibly cause cancer after exposure?

a. Neurologic molds
b. Allergenic molds
c. Pathogenic molds
d. Toxigenic molds

Ten Things You Should Know About Mold

Killing Toxic Black Mold
Mold on floor due to moisture.
  1. Potential health effects and symptoms associated with mold exposures include allergic reactions, asthma, and other respiratory complaints.
  2. There is no practical way to eliminate all molds and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.
  3. If mold is a problem in your workplace, you must clean up the mold and eliminate sources of moisture.
  4. Fix the source of the water problem or leak to prevent mold growth.
  5. Reduce indoor humidity (to 30-60%) to decrease mold growth.
  6. Clean and dry any damp or wet building materials and furnishings to prevent mold growth.
  7. Clean mold off hard surfaces with water and detergent, and dry completely.
  8. Absorbent materials, such as ceiling tiles, that are moldy may need to be replaced.
  9. Prevent condensation on cold surfaces by adding insulation.
  10. In areas where there is a perpetual moisture problem, do not install carpeting.

Remember, molds can be found almost anywhere; they can grow on virtually any substance, providing moisture is present.

5. Since there is no way to eliminate all molds indoors, what is the primary control method?

a. Control temperature
b. Control moisture
c. Control ventilation
d. Control animals

Mold Cleanup

Use PPE and ventilate during cleanup.

There are several things to be aware of while cleaning up mold on a construction site. Here are a few things to remember.

  • Non-porous materials (e.g., metal, glass, hard plastics, etc.) can be dried out, fully cleaned and reused. Clean hard and non-porous materials using a detergent. Surfaces can be rinsed with a disinfectant made of ½ cup liquid household bleach mixed into one gallon of water (Caution: DO NOT mix bleach with cleaning products that contain ammonia).
  • Semi-porous materials (e.g., wood and concrete) can be cleaned if they are structurally sound.
  • Porous materials (e.g., drywall, carpets, insulation, ceiling tile, etc.) are different because mold penetrates into them making it very difficult to fully clean. As a general rule, if a porous material has been wet for over 48 hours it is best to remove and replace.

Source: OSHA Pub 3713, Mold Hazards during Disaster Cleanup.

CAUTION: Do not mix bleach with other cleaning products that contain ammonia. Highly toxic chlorine gas can be produced.

  • Avoid breathing mold spores. A N-95 respirator is recommended.
  • Avoid touching mold with your bare hands. Long gloves that extend to the middle of the forearm are recommended. Use ordinary household rubber gloves when cleaning surfaces with water, bleach, and a mild detergent. Gloves made from natural rubber, neoprene, nitrile, polyurethane, or PVC are recommended if using a disinfectant, biocide, or strong cleaning solution.
  • Avoid getting mold spores in your eyes. Goggles without ventilation holes are recommended.

6. What is a recommended way to avoid exposure to mold spores when cleaning a surface?

a. Wear an N-95 respirator
b. Breathe in through the nose and out through the mouth
c. Wear a dust mask with two straps
d. Wear a self-contained breathing apparatus (SCBA)

Respiratory Protection

Half-Mask, Elastomeric, Air Purifying Respirator

Respirators protect cleanup workers from inhaling airborne mold, contaminated dust, and other particulates that are released during the remediation process. Either a half-mask or full-face piece air-purifying respirator can be used. A full-face piece respirator provides both respiratory and eye protection. More protective respirators may have to be selected and used if toxic contaminants such as asbestos or lead are encountered during remediation.

Respiratory protection is effective only if:

  • the correct respirator is used
  • it's available when you need it
  • you know when and how to put it on and take it off
  • you have stored it and kept it in working order in accordance with the manufacturer's instructions

Respiratory protection for exposure to mold will depend on the size of the particle and its level of toxicity.

  • Whenever you smell or see the presence of mold, it is important to take precautions to limit your exposure to mold and mold spores.
  • To limit your exposure to airborne mold, wear an N-95 respirator.
  • If oil is present in the air, make sure to use either an R or a P designed filter.

7. What does the need for respiratory protection depend on when exposed to mold?

a. The shape of the mold spore
b. The concentration of mold spores in the air
c. The particle size and level of toxicity of the mold
d. The particle length and concentration of spores

Poisonous Plants

Insect Protection and Poisonous Plants
poison ivy
Watch out for poison oak and ivy when working in the woods.

Many native and exotic plants are poisonous to humans when ingested or if there is skin contact with plant chemicals. However, the most common problems with poisonous plants arise from contact with the sap oil of several plants that cause an allergic reaction: poison ivy, poison oak, and poison sumac.

Poison ivy, poison oak, and poison sumac release oil when the leaf or other plant parts are bruised, damaged, or burned. Approximately 85 percent of the general population will develop an allergy if exposed to these plants. The sensitivity to the sap usually develops after several encounters with poison ivy, oak, or sumac. When the oil gets on the skin, an allergic reaction, referred to as contact dermatitis, occurs in most exposed people as an itchy red rash with bumps or blisters.

Plant Identification

You might have heard the old saying "Leaves of three, let it be!" It is a helpful reminder for identifying poison ivy and oak, but not poison sumac which usually has clusters of 7-13 leaves. Even poison ivy and poison oak may have more than three leaves and their form may vary greatly depending upon the exact species encountered, the local environment, and the season.

Being able to identify local varieties of these poisonous plants throughout the seasons and differentiating them from common non-poisonous look-a-likes are the major keys to avoiding exposure.

8. What causes an allergic reaction when workers are exposed to poison ivy, oak or sumac?

a. The solvent given off by the plant is absorbed
b. The spores given off and inhaled with contact
c. The tips of the leaves penetrating the skin
d. The oil of the plant contacting the skin

Poison Ivy

poison ivy
Poison Ivy
Click to Enlarge

If you are working in a wooded area, you want to be on the lookout for poison ivy. It is everywhere in the United States except Hawaii and Alaska. In the East, Midwest, and the South, it grows as a vine. In the Northern and Western United States, it grows as a shrub. Each leaf has three leaflets. Leaves are green in the summer and red in the fall. In the late summer and fall, white berries may grow from the stems.

Here are a few things to remember about poison ivy.

  • Eastern poison ivy is typically a hairy, rope-like vine with three shiny green (or red in the fall) leaves budding from one small stem.
  • Western poison ivy is typically a low shrub with three leaves that do not form a climbing vine. May have yellow or green flowers and white to green-yellow or amber berries.
poison oak
Poison Oak
Click to Enlarge

Poison Oak

Poison oak is usually a shrub with leaves of three, similar to poison ivy. It has oak-like leaves in clusters of three. There are two distinct kinds: Eastern poison oak and Western poison oak.

  • Eastern poison oak (New Jersey to Texas) grows as a low shrub.
  • Western poison oak (Pacific Coast) grows to six-foot-tall clumps or vines up to 30 feet long. It may have yellow or green flowers and clusters of green-yellow or white berries.

9. Which poisonous plant has can grow into six-foot clumps up to 30 feet long?

a. Western poison oak
b. Northern poison oak
c. All types of poison oak
d. Eastern poison oak

Poison Sumac

poisonous plants
Poison sumac
Click to Enlarge

In the United States, poison sumac grows in standing water in peat bogs in the Northeast and Midwest and in swampy areas in parts of the Southeast. Each leaf has clusters of seven to 13 smooth-edged leaflets. The plants can grow up to 15 feet tall. The leaves are orange in spring, green in summer, and red, orange, or yellow in fall. There may be clumps of pale yellow or cream-colored berries.

Poisonous Plant Exposure Symptoms and Solutions

Sign and symptoms of poison ivy, oak, and sumac include:

  • itching
  • redness
  • burning sensation
  • swelling
  • blisters
  • rash (may take up to 10 days to heal).

Possible solutions and controls for poison ivy, oak, and sumac include:

  • Wear long-sleeved shirts and long pants, tucked into boots. Wear cloth or leather gloves.
  • Apply barrier creams to exposed skin.
  • Educate workers on the identification of poison ivy, oak, and sumac plants.
  • Educate workers on signs and symptoms of contact with poisonous ivy, oak, and sumac.
  • Keep rubbing alcohol accessible. It removes the oily resin up to 30 minutes after exposure.

10. How can you decrease the effects of poison sumac exposure?

a. Rub the resin off with a clean towel
b. Use rubbing alcohol to remove the oily resin
c. Use soap so clean the affected area
d. Neutralize the resin with sodium ascorbate
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