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Best Practices in Occupational Health and Hygiene for the Energy-from-Waste Industry

Oct. 5, 2012
Implement these proactive techniques to protect workers in the energy-from-waste industry.

Americans generate 390 million tons of trash each year, resulting in some 270 million tons of waste that end up in landfills annually.1 While the nation strives to find suitable and new sources of energy, the energy-from-waste (EfW) industry is providing sustainable solutions by turning that waste into clean, renewable electricity using technologically advanced means.

Generating that clean energy, however, must be done safely, and health and safety professionals must ensure employees in the industry are protected from workplace hazards and stresses. Covanta Energy, a global owner and operator of EfW projects, has implemented many best practices for protecting workers in this industry, such as how to protect against harmful lead exposure and ways to continue moving toward a safer and cleaner future.

6 Steps for Continuous ImprovementStep 1: Improve equipment design and maintenance.
Step 2: Prioritize exposures before sampling.
Step 3: Wipe lunch tables, countertops, control room desktops, etc.
Step 4: Wipe worker hands before and after work.
Step 5: Wipe the insides of the respirators.
Step 6: Use medical surveillance to determine what gets into the worker's body.

Testing for Lead

Today's modern EfW facilities use municipal solid waste as fuel for the energy-generating process. A wide variety of man-made items containing lead are found in the waste, including batteries, plastic toys, home décor items, kitchen utensils, cosmetic products and jewelry. After combustion, 10 percent of the incoming waste volume remains as ash, and the lead from these products becomes a small but important component of the ash residue. With lead remaining in the ash, facility workers who inhale or ingest ash may face lead exposure.

To monitor the working environment and protect against exposure, industrial hygienists regularly test the workplace ambient air for lead while workers perform their daily tasks. Blood tests also are administered to determine whether inhaled or ingested lead actually entered the body. As stipulated by the OSHA lead regulation, 29 CFR1910.1025, blood lead testing is made available to workers who may be exposed above the OSHA lead airborne action level (AL) of 30 micrograms (µg)/m3 for more than 30 days per year.

While the OSHA regulation specifies that worker blood lead levels must be kept below 40 µg/dl of whole blood (Point A on the chart), current studies on adult blood lead levels now are reporting adult health effects at 10 µg/dl or lower (Point B on the chart). These studies also suggest medical removal should be considered above the 10 µg/dl level. To put these numbers into perspective, the unexposed U.S. average blood lead level (geometric mean) for adult males aged 29-59 is reported as 2.0 µg/dl (Point C on the chart below).

Evaluate  Work Exposures

Workers in the EfW industry perform a range of jobs and include boiler operators, utility operators, mechanics, regional maintenance workers, certified welders and technicians. Industrial hygienists must evaluate all job tasks to determine each worker's necessary level of protection.  Most of the worker activities are associated with routine maintenance checks on the equipment. Many years of conducting industrial hygiene monitoring for these routine maintenance workers typically produced lead results below the OSHA AL. 

Use Sound Design, Operation and Maintenance to Keep Exposures Low1. Design facilities with technical standards that capture best available design and control technologies.
2. Enclose equipment such as conveyors that can aerosolize the ash.
3. Submerge or spray the ash with water.
4. Keep the areas under negative pressure with ventilation.
5. Institute good maintenance programs: keep up with equipment maintenance and repairs; seal openings as soon as they are noticed with interim measures until repairs are complete; keep belt scrapers tight to avoid spillage; and develop boiler reliability groups that specialize in optimizing boiler performance.
6. Maintain a good housekeeping program: vacuum whenever possible; wash down the area; and spread a sweeping compound on solid surfaces prior to any dry sweeping – they contain “oily” ingredients that stick particles together and reduce ash aerosolization.

In contrast, regional maintenance workers travel from facility to facility to weld and repair boiler tubes. These workers are in confined spaces daily, where ash and welding fume exposure is typical, and where industrial hygiene monitoring results are frequently above the OSHA AL for lead. Varying types of respiratory protection are required, depending on the duration and nature of the work tasks being performed. The selection often includes full-face, powered air-purifying respirators (PAPRs) and sandblast hoods and, less frequently, supplied air.

How do all of these variables come together into a worker health program to be sure workers receive the highest quality of protection? Let's break it down:

Use sound design, operation and maintenance – Sound facility design with equipment enclosures, predictive and preventative maintenance programs and a distributed control system (DCS) optimize equipment operation and are integral features of modern EfW facilities. Enclosures of ash processing and handling equipment help ensure that ambient ash exposures are kept to a minimum.

Enhance respiratory protection requirements – Covanta's respiratory protection requirements have been in place for more than 20 years. Early on, workers could choose from a range of respirators, as long as they selected a respirator with enough protection for the job being performed. But in 2005, a more rigorous, minimum full-face, tight-fitting respirator policy was implemented for confined space boiler work. The change was intended to provide improved eye protection and resulted in a decline in eye injuries.

In addition, lead levels declined in both work groups after discontinuing the use of half-face respirators, suggesting that the minimum full-face respirator requirement may have contributed to that change.

Looking to further improve protection for the regional maintenance group, a TSI Portacount minimum quantitative respirator fit factor was set at 5,000 (10 times the threshold required by OSHA) in 2010. Superior fitting respirators limit exposure to respiratory hazards and as expected, the blood lead levels of regional maintenance workers further improved after fit factor requirements were increased.

Stop hand-to-mouth transfer – Ingestion is another contributor to blood lead levels in EfW facility workers. Workers may come in contact with ash sediments on their skin, most often on their hands when gloves are not worn. If hands aren't properly cleansed, hand-to-mouth transfer of the ash might occur while eating, smoking or drinking. In 2008, to minimize the potential for hand-to-mouth transfer, Covanta implemented a facility surface wipe testing policy. In 2010, a worker hand wipe testing policy was added, and in 2011, a respirator wipe testing policy was initiated.

Communicating these efforts at Covanta has provided workers with additional education, proactively engaging them in the cleanliness of their workplace and in the management of their personal protective equipment. With increased worker awareness of the environment and the exposures, the ability to more directly react to and reduce individual exposures has been significant, while aiding in the overall improvement of facility hygiene.

Step up the program – Ensuring workers are continuously protected from workplace lead requires a concentrated effort with clearly communicated and actively practiced guidelines and methodologies. In addition to lead exposure control policies, workers need to be fully trained and knowledgeable, not just about the health effects of lead, but also about how to prevent exposure. In 2009, Covanta initiated STEP-UP (Safety Today and Every day is Paramount – Unleash the Power), a signature safety program designed to accelerate continuous improvements in safety and health performance through increased commitment and communication across all labor and business units. The returns from STEP-UP have thrust even the blood lead program to new levels, illustrating how a unified focus on safety and health can drive overall success.

Assess non-occupational exposure – In addition to workplace tasks, many sources outside of the workplace can contribute to lead exposure, including hunting, target shooting, cigarette smoking, consumption of lead-containing dietary supplements and contaminated well water, and renovations of residential lead-based painted surfaces. Although no adjustments were made for the impact of non-occupational lead exposure in the chart, non-occupational factors can be significant. At Covanta, an internal "action level" of 10 µg/dl has been set. A blood lead test above the action level triggers additional testing to confirm the result, completion of a questionnaire and interview, and repeat respirator fit testing. The added focus helps differentiate the potential occupational versus non-occupational exposure contributions. Follow-up actions are taken in either case, with the intention of providing the best level of protective care available.

Quantify the results – By advancing its health and hygiene program, average blood lead levels at Covanta declined between the years 2005 and 2011, as shown in the chart for both work groups. The routine maintenance worker levels dropped from 5.0 to 3.1 µg/dl (Points D and E on the chart), and regional maintenance worker levels dropped from 13.4 to 5.7 µg/dl (Points F and G on the chart).2

While periodic blood lead testing is an industry standard, the implementation of a more robust program has proven to better protect workers.

A Safer, Cleaner Future

Covanta is focused on preventing illness and injury and serves as a model for worker safety in the EfW industry. In fact, several OSHA VPP evaluators have described Covanta's industrial hygiene program as a best practice. Currently, the company is among the top seven companies participating in OSHA's Voluntary Protection Program nationwide. Additionally, more than half of Covanta's 50 U.S.-based operating facilities have been incident-free for at least one year, with three that have been injury-free for more than 10 years.

To continue moving toward a safer and cleaner work force, companies should emphasize continuous improvement and best practices while striving to exceed guidelines provided by organizations such as the American Conference of Governmental Industrial Hygienists (ACGIH) and the American Industrial Hygiene Association (AIHA). While exceeding regulatory requirements, as described in this article, is not always necessary, environmental health and safety professionals can develop stringent preventative programs to achieve continuous health and safety improvements and minimize worker exposures to lead and other contaminants while enhancing the overall well-being of workers in the workplace.

1 "The 2010 State of Garbage in America," a joint study by BioCycle and the Earth Engineering Center of Columbia University.
2  Dr. Peter Greaney of WorkCare, Inc., Covanta's medical surveillance partner, reviews and verifies the accuracy of all blood lead testing for quality assurance purposes. No violation of HIPAA has occurred by publishing this aggregate data.

Justin August is a certified industrial hygienist with a bachelor's degree in chemical engineering and a master's of science (applied) in occupational health from McGill University in Montreal. Over the last 15 years, he has worked to improve the environment for employees at Merck Frosst Canada Inc., American Ref-Fuel Company and Covanta Energy Corp.

Beth Hurley serves as the vice president of safety and health at Covanta Energy Corp. and has more than 33 years of experience as a safety professional and certified industrial hygienist. She holds a bachelor's degree in chemistry and biology and a master's of science in public policy.

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