Respiratory hazards include harmful substances and below-normal concentrations of oxygen in the air we breathe. What makes a substance harmful depends on its toxicity, chemical state, physical form, concentration, and the period of time one is exposed. Examples include:
Harmful effects are wide ranging and may occur immediately (acute) or take years to develop (chronic).
Particulates: These are airborne particles such as dust, fibers, fumes, mists, soot, and smoke. Some are so small they can only be seen with an electron microscope. The diameter of a particulate is usually measured in micrometers (one micrometer equals 1/1,000 millimeter or 1/25,400 inch). Particles with diameters under 10 micrometers are more likely to enter the respiratory system.
Gas and vapors: Gases can spread freely in the air. Vapors are the gaseous states of substances that are liquids or solids at room temperature. Gases and vapors are classified by their chemical forms.
Biological organisms: These include bacteria, viruses, fungi, and other living organisms that can cause respiratory infections.
Oxygen-deficient atmosphere: Normal air has an oxygen concentration of 20.8 percent by volume. When the concentration drops below 19.5 percent, the air is oxygen deficient and considered immediately dangerous to life and health (IDLH). The harmful effects of oxygen deficiency include impaired thinking and coordination, unconsciousness, and death.
Protect yourself and your co-workers from respiratory hazards by doing the following:
This three-step process, summarized below, is called a hazard analysis or hazard evaluation.
After you have identified respiratory hazards, evaluate employees’ exposures to determine whether they are exposed to unsafe levels. Evaluate exposures by measuring them or estimate them with data from previous exposure measurements. Three examples:
Immediately dangerous to life and health (IDLH) refers to an atmospheric concentration of a toxic, corrosive, or asphyxiant substance that poses an immediate threat to life, causes irreversible health effects, or interferes with one’s ability to escape from a dangerous atmosphere. If employees may be exposed to such substances and you are unable to evaluate their exposures, you must consider the exposure immediately dangerous to life and health.
Exposure monitoring is the testing of air samples to determine the concentration of contaminants in a work environment. Test data from the samples are averaged over a period of time, usually eight hours, and referred to as a time-weighted average (TWA).
OSHA has established permissible exposure limits (PEL) for specific air contaminates. Exposures must not exceed the eight-hour PEL-TWA in any eight-hour work shift.
Permissible exposure limits are listed in OSHA Standard 1910.1000, Table Z-1 Limits for Air Contaminants, Table Z-2 Toxic and Hazardous Substances, and Table Z-3, Mineral Dusts.
A trained specialist, such as an industrial hygienist, can help you evaluate employee exposures, interpret the results, and suggest how to lower exposures to safe levels.
To eliminate or reduce the chance of getting hurt in the workplace, OSHA requires employers to use a prioritized set of hazard control strategies called the Hierarchy of Controls. The highest priority strategies attempt to eliminate, replace or use engineering to manage the hazard, itself. The lower level strategies work to reduce exposure by controlling worker behaviors. Let’s take a look at these strategies.
If employees are exposed to respiratory hazards at unsafe levels, you’ll need to determine how to protect them from overexposure. You might try to:
For instance, when performing abrasive blasting, the worker might replace blasting sand, which contains silica, with abrasive media such as glass beads, corn cob, or air and dry ice.
If you can’t eliminate or replace a respiratory hazard, use engineering controls to lower exposures to safe levels. Such controls “engineer” or physically change the work environment, so the air is safe to breathe. Examples of engineering controls include:
Administrative controls establish programs and policies that require employees to use processes, procedures, and practices to help to limit exposure to hazardous substances. As you can see, the primary strategy is to control behaviors to limit exposure. Some examples of administrative controls related to respiratory protection include:
Employees must use respirators for protection from respiratory hazards when engineering controls are not feasible or will not reduce their exposures to safe levels.
Assigned Protection Factor (APF) means the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees when you implement a continuing, effective respiratory protection program.
For higher-risk exposure situations (i.e., a higher concentration of infectious particles), choosing a respirator with a higher APF provides a higher level of protection for the wearer. The APFs for different types of respirators are presented in Table 1 of the OSHA Respiratory Protection Standard 1910.134. (See table to the right).
Maximum Use Concentration (MUC) means the maximum atmospheric concentration of a hazardous substance from which an employee can be expected to be protected when wearing a respirator. It is determined by the assigned protection factor of the respirator or class of respirators and the exposure limit of the hazardous substance.
For more information see OSHA Publication 3352, Assigned Protection Factors for the Revised Respiratory Protection Standard.
Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.
Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.