Module 4 - Home

Physical and Emerging Hazards

Modular Learning Outcomes

Upon successful completion of this module, the student will be able to satisfy the following outcomes:

· Case

· Compare and contrast solid waste management strategies.


· Apply principles of hazard recognition and control to assess occupational noise hazards and design a hearing conservation program.

· Discussion

· Discuss physical and emerging hazards in environmental and occupational health.

Module Overview

This module will focus on solid waste management issues and on physical and emerging hazards in the environment. Physical hazards include noise, radiation, heat stress, and cold; we will discuss noise.

Solid Waste Management

Municipal Solid Waste: Municipal Solid Waste (MSW)—more commonly known as trash or garbage—consists of everyday items such as product packaging, grass clippings, furniture, clothing, bottles, food scraps, newspapers, appliances, paint, and batteries. In 2005, U.S. residents, businesses, and institutions produced more than 245 million tons of MSW, which is approximately 4.5 pounds of waste per person per day.

Hazardous Waste

Hazardous waste is waste with properties that make it dangerous or potentially harmful to human health or the environment. The universe of hazardous waste is large and diverse. Hazardous waste can be liquids, solids, contained gases, or sludges. It can be the by-product of manufacturing processes or simply discarded commercial products, like cleaning fluids or pesticides.

Noise Pollution


Exposure to loud noises can cause temporary or permanent hearing loss. This is referred to as Noise Induced Hearing Loss (NIHL). On an isolated exposure to loud noise, there can be a temporary noise-induced threshold shift in one’s hearing. However, repeated exposure can cause a permanent noise induced threshold shift. The victim may experience tinnitus, a sometimes painful ringing in the ears.

According to NIOSH, 30 million Americans are exposed to noise while on the job at levels hazardous to their hearing. Almost any worker can be at risk for noise induced hearing loss in the workplace. However, NIOSH states that workers in some specific industries have higher exposures to dangerous levels of noise (e.g., agriculture, mining, construction, manufacturing and utilities, transportation, and military). 

Protective devices should be worn to prevent hearing loss to the maximum extent possible. Hearing protection devices are given a noise reduction rating by two prominent organizations. There are various types of plugs including expandable foam plugs, pre-molded re-usable plugs, canal caps, and earmuffs.

Community noise (also called environmental noise, residential noise, or domestic noise) is defined as noise emitted from all sources, except noise at the industrial workplace. Main sources of community noise include road, rail, and air traffic; industries; construction and public work; and the neighborhood. Typical neighborhood noise comes from premises and installations related to the catering trade (restaurant, cafeterias, discotheques, etc.); live or recorded music; sporting events, including motor sports; playgrounds and car parks; and domestic animals (such as barking dogs). The main indoor sources are ventilation systems, office machines, home appliances, and neighbors. Although many countries have regulations on community noise from road, rail, and air traffic, and from construction and industrial plants, few have regulations on neighborhood noise. This is probably due to the lack of methods to define and measure it, and to the difficulty of controlling it. In developed countries, too, monitoring of compliance with, and enforcement of, noise regulations is weak for lower levels of urban noise that correspond to occupationally controlled levels. Recommended guideline values based on the health effects of noise, other than occupationally induced effects, are often not taken into account.


Definition of Radiation

Radiation is energy that travels in the form of waves or high-speed particles. There are many different types of radiation that have a range of energy forming the electromagnetic spectrum.

The spectrum has two major divisions:

· non-ionizing radiation

· ionizing radiation

Radiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons, is referred to as “non-ionizing radiation.” Examples of this kind of radiation are sound waves, visible light, and microwaves.

Radiation that falls within the “ionizing radiation” range has enough energy to remove tightly bound electrons from atoms, thus creating ions. This is what people usually think of as “radiation.” We take advantage of its properties to generate electric power, to destroy cancer cells, and in many manufacturing processes.

Definition of Radioactivity

Radioactivity is the property of some atoms that causes them to spontaneously give off energy as particles or rays. Radioactive atoms emit ionizing radiation when they decay.

What Is Radioactive Decay?

It is the decrease in the amount of any radioactive isotope with the passage of time due to the spontaneous emission of radiation from the atomic nuclei (either alpha or beta particles, often accompanied by gamma radiation), and consequent transformation to a different chemical form. For example, uranium-238 decays through a series of steps to become a stable form of lead. 

What Is Half -Life?

The rate of radioactive decay is characteristic of each radionuclide. Scientists talk about this rate as a radionuclide's radioactive half-life, commonly referred to as just half-life. It is the time required for the disintegration of one-half of the radioactive atoms that are present when measurement starts. It does not represent a fixed number of atoms that disintegrate, but a fraction.

The half-life tells how quickly the radioactivity from the radionuclide will decrease. The number of curies tells how active it is now.

Health Effects Associated with Exposure to Radiation

Radioactive materials that decay spontaneously produce ionizing radiation, which has sufficient energy to strip away electrons from atoms (creating two charged ions) or to break some chemical bonds. Any living tissue in the human body can be damaged by ionizing radiation in a unique manner. The body attempts to repair the damage, but sometimes the damage is of a nature that cannot be repaired or it is too severe or widespread to be repaired. Also mistakes made in the natural repair process can lead to cancerous cells. The most common forms of ionizing radiation are alpha and beta particles, and gamma and X-rays.

Radiation Protection

Three basic concepts apply to all types of ionizing radiation:

1. Time: The amount of radiation exposure increases and decreases with the time people spend near the source of radiation. In general, we think of the exposure time as how long a person is near radioactive material. It's easy to understand how to minimize the time for external (direct) exposure. Gamma and X-rays are the primary concern for external exposure. However, if radioactive material gets inside your body, you can't move away from it. You have to wait until it decays or until your body can eliminate it. When this happens, the biological half-life of the radionuclide controls the time of exposure. Biological half-life is the amount of time it takes the body to eliminate one half of the radionuclide initially present. Alpha and beta particles are the main concern for internal exposure.

2. Distance: The farther away people are from a radiation source, the less their exposure. How close to a source of radiation can you be without getting a high exposure? It depends on the energy of the radiation and the size (or activity) of the source. Distance is a prime concern when dealing with gamma rays, because they can travel long distances. Alpha and beta particles don't have enough energy to travel very far. As a rule, if you double the distance, you reduce the exposure by a factor of four. Halving the distance increases the exposure by a factor of four. For example, the exposure of an individual sitting 4 feet from a radiation source will be 1/4 the exposure of an individual sitting 2 feet from the same source

3. Shielding: The greater the shielding around a radiation source, the smaller the exposure. Shielding simply means having something that will absorb radiation between you and the source of the radiation (but using another person to absorb the radiation doesn't count as shielding). The amount of shielding required to protect against different kinds of radiation depends on how much energy they have: Alpha: A thin piece of light material, such as paper, or even the dead cells in the outer layer of human skin provides adequate shielding because alpha particles can't penetrate it. However, living tissue inside body, offers no protection against inhaled or ingested alpha emitters. Beta: Additional covering, for example heavy clothing, is necessary to protect against beta-emitters. Some beta particles can penetrate and burn the skin. Gamma: Thick, dense shielding, such as lead, is necessary to protect against gamma rays. The higher the energy of the gamma ray, the thicker the lead must be. X-rays pose a similar challenge, so X-ray technicians often give patients receiving medical or dental X-rays a lead apron to cover other parts of their body.