Chapter 20

1. Chapter 20 Industrial Hygiene: Toxic Substances and Confined Spaces

2. Major Topics • Hazards in the workplace • OSH Act and industrial hygiene • Airborne contaminants • Asbestos hazards • Sick building syndrome • NIOSH and industrial hygiene • OSHA confined spaces standard

3. Industrial Hygiene • Industrial hygiene is a safety and health profession that is concerned with predicting, recognizing, assessing, controlling, and preventing environmental stressors in the workplace that can cause sickness or serious discomfort to workers. • Common stressors include gases, fumes, vapors, dusts, mists, noise, and radiation.

4. Responsibilities of the modern industrial hygienist • Code of ethics of the American Academy of Industrial Hygiene: • To ensure the health of employees • To maintain an objective approach in recognizing, assessing, controlling and preventing health hazards regardless of outside pressure and influence. • To help employees understand the precautions that they should take to avoid health problems. • To respect employees honesty in matters relating to industrial hygiene • To make the health of employees a higher priority than obligations to the employer

5. Role of the safety and health professional • In companies that employ specialists, their recommendations are used by safety and health professionals to develop, implement, monitor, and evaluate the overall safety and health program. • If specialists are not employed, safety and health professionals are responsible for seeking the advice and assistance necessary to predict, recognize, assess, control, and overcome environmental stressors that may cause sickness or serious discomfort to employees.

6. OSHA requirements relating to industrial hygiene • Use of warning labels and other means to make employees aware of potential hazards, symptoms of exposure, precautions, and emergency treatment • Prescription of appropriate personal protective equipment and other technological preventive measures [29CFR 1910.133 and 1910.134 subpart I] • Provision of medical tests to determine the effect on employees of exposure to environmental stressors • Maintenance of accurate records of employee exposures to environmental stressors that are required to be measured or monitored • Accessibility of monitoring tests and measurement activities to employees • Availability of monitoring tests and measurement activity records to employees on request • Notification of employees who have been exposed to environmental stressors at a level beyond the recommended threshold and corrective action being taken

7. Typical categories of hazard in the workplace • Categories: chemical, physical, biological and ergonomic. • Chemical hazards: include mists, vapors, gases, dusts, and fumes. • Physical hazards: include noise, vibration, extremes of temperature, and excessive radiation. • Biological hazards: come from molds, fungi, bacteria, and insects. Bacteria may be introduced in the workplace through sewage, food waste, water or insect droppings. • Ergonomic hazards: poorly designed workstations and tools, conditions that put workers in awkward positions or impair their visibility.

8. Routes of entry for toxic agents • The most common routes of entry for toxic agents are inhalation, absorption, injection, and ingestion.

9. Airborne contaminants: dust, fumes, smoke, mists, and gases • Dusts are various types of solid particles that are produced when a given type of organic or inorganic material is scrapped, sawed, ground, drilled, handled, heated, crushed or otherwise deformed. The degree of the hazard depends on the toxicity of the parent material and the size and level of concentration of the particles. • Fumes: Welding, heat treating, and metalizing all involve the interaction of intense heat with the parent material, which results in tiny particles of the parent material which can be inhaled. • Smoke: Smoke is the result of incomplete combustion of carbon material. Tiny soot or carbon particles remain that can be inhaled. • Aerosols: are liquid or solid particles that are so small that they can remain suspended in air long enough to be transported over a distance. They can be inhaled. • Mists: are tiny liquid droplets suspended in the air. Mists are formed when vapors return to a liquid state through condensation and when the application of a sudden force or pressure turns a liquid into particles. • Gases: become hazardous when they fill a confined unventilated space. The mist common forms of gases in industrial settings are from welding and the exhaust from internal combustion engines.

10. Remove or contain asbestos • Following factors should be considered: • Is there evidence that the ACM (asbestos containing material) is deteriorating? What is the potential for further deterioration? • Is there evidence of physical damage to the ACM? What is the potential for future damage? • Is there evidence of water damage to the ACM or spoilage? What is the potential for future damage or spoilage? • The most widely used methods for dealing with asbestos are removal, enclosure and encapsulation.

11. ANSI Z9.8 (indoor air quality/HVAC) • General Coverage: ANSI Z9.8 is very specifically written to apply primarily to office space. It applies specifically to employee occupancies in non industrial spaces including general office spaces, commercial operations, and office spaces with industrial facilities. • Application flexibility: When the provisions of ANSI Z9.8 conflict with other standards the more stringent standard is to take precedence. • Acceptable air quality: Employers may establish ceiling limits (e.g. if more than 2% of the employees complain about air quality problems the ceiling limit has been reached). • Tobacco smoke: The standard requires that employers evaluate smoking in the workplace and apply whatever management controls are appropriate.

12. Asbestos: removal, enclosure and encapsulation • Removal: known as asbestos abatement. The area in question must be completely enclosed in walls of tough plastic. The enclosed area must be ventilated by High efficiency particle absolute (HEPA) filtered negative air machines. The ACM (asbestos containing material) must be covered with a special liquid solution to cut down on the release of asbestos fibers. The ACM must be placed in leak proof containers for disposal. • Enclosure: use HEPA filtered negative air machines in conjunction with drills or any other tools that may penetrate or otherwise disturb ACMs. Construct the enclosing walls of impact resistant air tight material. Post signs indicating the presence of ACMs within the enclosed area. Note the enclosed area on the plans of the building. • Encapsulation: of asbestos involves spraying the ACMs with a special sealant that binds them together thereby preventing the release of fibers. The sealant should harden into a tough impact resistant skin. This approach is generally used on acoustical plaster and similar materials.

13. Medical examinations for employees who handle ACMs • Medical examinations conducted at least annually should be required for employees who handle ACMs. These examinations should include front and back chest X-rays that are at least 7 “ by 14”. The examination should also test pulmonary function, including forced vital capacity and forced expiratory volume at one second. • Medical records on such employees should be kept for at least 20 years. They should contain the complete medical history of the employee. These records must be made available on request to employees, past employees, health care professionals, employee representatives, and OSHA personnel.

14. Exposure thresholds: time weighted average, short term exposure limit, and exposure ceiling • Threshold Limit Value-Time weighted average (TLV-TWA): The time weighted average for a conventional 8 hour work day and 40 hour work week for a given substance to which it is believed that nearly all workers may be repeatedly exposed on a daily basis without suffering ill effects. For example the TLV-TWA for liquefied petroleum gas is 1000 parts per million (ppm). • Threshold Limit Value-Short term exposure limit (TLV-STEL): A STEL is defined as a 15 minute TWA exposure that should not be exceeded at any time during the work day period. It should not occur more than 4 times in the day (with at least 60 minutes between exposures). For example the TVL-STEL for isopropyl ether is 310 ppm. • Threshold Limit Value-Ceiling (TLV-C): The concentration of a given substance that should not be exceeded at any point during an exposure period.

15. Evaluating hazards in the workplace • For hazard evaluation the following considerations are important: • The nature of the material or substance involved, the intensity of the exposure, and the duration of the exposure. • Key factors to consider are how much exposure is required to produce injury or illness; the likelihood that enough exposure to produce injury or illness will take place; the rate of generation of airborne contaminants; the total duration of the exposure; and the prevention and control measures used.

16. Generic prevention and control strategies • Most prevention and control strategies can be placed in one of the following 4 categories: • Engineering controls • Ventilation • Personal protective equipment • Administrative controls

17. Prevention/control strategy: engineering controls, ventilation, personal protective equipment • Engineering Controls: replacing toxic material with one that is less hazardous or redesigning a process to make it less stressful or to reduce exposure to hazardous material or conditions, isolating hazardous process to reduce the number of people exposed to it and introducing moisture to reduce dust. • Ventilation: exhaust ventilation involves trapping and removing contaminated air. Used with such processes as abrasive blasting, grinding, polishing, buffing, and spray painting or finishing. Dilution ventilation involves simultaneously removing and adding air to dilute a contaminant to acceptable levels. • Personal protection: Personal protective equipment (PPE) imposes a barrier between the worker and the hazard. Typical equipment include safety goggles, face shields, gloves, boots, earmuffs, ear plugs, full body clothing, and respirators. • Specially designed eyewash and emergency wash stations (fig 20-8, 9, 10) should be readily available and accessible in any work setting where contaminants may be present.

18. Worker self protection strategies • Know the hazards in your workplace: take time to identify all hazardous material and conditions in your workplace and know the safe exposure levels of each. • Know the possible effects of hazards in your workplace: Typical effects of workplace hazards include respiratory damage, skin disease and irritation, injury to the reproductive system, and damage to the blood, lungs, central nervous system, eyesight and hearing. • Use PPE properly: Choosing the right equipment, getting a proper fit, correctly cleaning and storing equipment, and inspecting equipment regularly for wear and damage. • Understand and obey safety rules: Read warning labels before using any contained substance, handle materials properly, read and obey signs, and do only authorized work. • Practice good personal hygiene: Wash thoroughly after exposure to a hazardous substance, shower after work, wash before eating, and separate potentially contaminated work clothes from others before washing them.

19. NIOSH and Industrial Hygiene • The National Institute of Safety and Health [NIOSH] is part of the Department of Health and Human Services [HHS]. • The main focus of the agency is on toxicity levels and human tolerance levels of hazardous substances. • NIOSH prepares recommendations for OSHA standards dealing with hazardous substances and NIOSH studies are made available to employers. • Their continually updated list of toxic materials and recommended tolerance levels are extremely helpful to industrial hygienists concerned with keeping the workplace safe.

20. Toxic Substance • A toxic substance is one that has a negative effect on the health of a person or animal.

21. Effect of a toxic substance • Toxic effects are functions of several different factors including the following: • Properties of the substance • Amount of the dose • Level of exposure • Route of entry • Resistance of the individual to the substance

22. Common routes of entry of toxic substances • The most common routes of entry of toxic substances are inhalation, absorption, injection and ingestion.

23. Dose-response relationship • A dose of toxic substance can be expressed in a number of different ways depending on the characteristic of the substance: amount per unit of body weight, amount per body surface area, or amount per unit of volume of air breathed. • Olishifski expressed the dose response relationship mathematically as : C * T = K • where: • C = concentration • T = duration (time) of exposure • K = constant

24. Dose threshold, lethal dose, and lethal concentration • Dose threshold: is the minimum dose required to produce a measurable effect. • Lethal dose: is the dose that is highly likely to cause death. • Lethal concentration: of an inhaled substance is the concentration that is highly likely to result in death. With inhaled substances the duration of exposure is critical because the amount inhaled increases with every unprotected breath.

25. Acute and chronic effects and exposures • Acute effects and exposures involves a sudden dose of a highly concentrated substance. They are usually the result of an accident that result in an immediate health problem ranging from irritation to death. • Chronic effects and exposures involve limited continual exposure over time. Consequently the associated health problem develops slowly. • Fig 20-3 page 439: selected toxic substances and the organs they affect most.

26. Classification of airborne toxics • Airborne toxic substances are classified according to the type of effect they have on the body. • The primary classifications are: • irritants - cause irritation to skin, eyes, nose, mouth, throat, and upper respiratory tract. • asphyxiants - disrupt breathing so severely that suffocation results. • narcotics/anesthetics - can inhibit normal operation of central nervous system. • With all airborne contaminants concentration and duration of exposure are critical concerns.

27. Carcinogen • A carcinogen is any substance that can cause a malignant tumor or a tissue that may become cancerous.

28. OSHA chemical process standard, EPA clean air act, and SARA • OSHA chemical process standard: The standard requires chemical producers to analyze their processes to identify potentially hazardous situations and to assess the extent of the hazard. Having done so they must accommodate this knowledge in their emergency response plans and take action to minimize the hazards. Specific additional requirements include: compiling process safety information, maintaining safe operating procedures, training and educating employees, maintaining equipment, conducting incident investigations, developing emergency response plans, and conducting safety compliance audits. • EPA clean air act (1990): The law is designed to reduce air pollution – in the form of hazardous air pollutants, acid rain, and smog – by 56 billion pounds per year. This includes a 75% reduction in air toxics, a 50% cut in acid rain, and a 40% decrease in smog. • Superfund Amendments and Reauthorization Act (SARA): This law is designed to allow individuals to obtain information about hazardous chemicals in their communities so that they can protect themselves in case of emergency. It applies to all companies that use, make, transport, or store chemicals.

29. Threshold limit value (TLV) • Threshold limit values: refer to airborne concentrations of substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect. • Threshold limits are based on the best available information from industrial experience, from experimental human and animal studies, and when possible a combination of the three.

30. Time weighted average and ceiling • The time weighted average for a conventional 8 hour work day and 40 hour work week for a given substance to which it is believed that nearly all workers may be repeatedly exposed on a daily basis without suffering ill effects. • Ceiling: the concentration of a given substance that should not be exceeded at any point during an exposure period.

31. NIOSH categories of respirators • Class N (not oil resistant): respirators may be used only in environments that contain no oil based particulates. They may be used in atmospheres that contain solids or non oil contaminants. • Class R (Oil resistant): respirators may be used in atmospheres containing any contaminant. However the filters in Class R respirators must be changed after each shift if oil based contaminants are present. • Class P (oil proof): respirators may be used in any atmosphere containing any particulate contaminant. • If there is any question about the viability of an air filtering respirator in a given setting, employees should use air supplying respirators. Air from the air is completely blocked out, and fresh air is provided via a self contained breathing apparatus.

32. Sick building syndrome • A sick building is one that makes people sick because it has become infested with mold, mildew, spores, and other airborne micro organisms. • Poor indoor air quality (IAQ) can cause a variety of health problems ranging from the temporary to the long term. • One of the keys in preventing sick building syndrome is air exchange. • Important factors in a building’s ability to eliminate contaminated air and bring in fresh air are: ventilation, air infiltration rates, airflow rates in ducts, airflow patterns, and fume exhaust.

33. OSHA confined space standard • The OSHA confined space standard (29 CFR 1910.146) mandates that entry permits be required before employees are allowed to enter a potentially hazardous confined space. • Before the permit is issued a supervisor, safety or health professional, should do the following: shut down equipment/power (locked/tagged), test the atmosphere (19.5 to 23.5% oxygen), ventilate the space, have rescue personnel stand by, maintain communication, and use a lifeline (can pull an unconscious employee out of a confined space).

34. OSHA hazard communication standard (29 CFR 1910.1200) • Any organization that uses hazardous material in the workplace is required to fully inform employees and on-site contractors of the hazards and to provide training concerning the safe handling, storage, and use of the materials.

35. Summary • Common airborne contaminants are dusts, fumes, smoke, mists, gases, and vapors. • Asbestos has been tied to respiratory cancer. • The American National Standards Institute (ANSI) developed its own national air quality standard (ANSI z9.8). • The National Institute of Occupational Safety and Health (NIOSH) is part of the Department of Health and Human Services. It conducts research and education in human tolerance levels to toxic materials. • A confined space management policy should include: administration, controls, training, and work team requirements. • Material Safety Data Sheets (MSDS) are an excellent source of information for safety and health professionals. • OSHA’s Hazard Communication Standard (29 CFR 1910.1200) requires organizations to inform employees and contractors of the presence of hazardous substances in the workplace and provide safe use training.

36. Home work • Answer questions 4, 9, 11, 16, 17, 26, 29, 30, 31, and 33 on page 477. • 4. List 5 OSHA requirements relating to industrial hygiene. • 9. Summarize the various elements of ANSI Z9.8 (indoor air quality/HVAC). • 11. What type of medical examinations should be required of employees who handle ACM’s (Asbestos Containing Materials). • 16. Explain 5 self protection strategies that employees can use in the workplace. • 17. How does NIOSH relate to industrial hygiene? • 26. Describe the basic provisions of the following standards: OSHA Chemical Process Standard, EPA Clean Air Act, and SARA. • 29. Explain the 3 NIOSH categories of respirators. • 30. What is sick building syndrome? • 31. Explain the major tenets of the OSHA Confined Space Standard. • 33. Summarize the requirements of OSHA’s Hazard Communication Standard.