Title:
Fluorescent bulb mercury clean-up method
Kind Code:
A1


Abstract:
Described herein is a method and instrumentation for cleaning up mercury spilled from broken fluorescent light bulbs. The method provides for the safe clean-up of the mercury spilled from four or fewer four-foot bulbs (or their equivalent) without the use of a respirator or other respiratory protection, while avoiding the expense associated with contracting an environmental remediation firm to perform the clean-up.



Inventors:
Grover, Terry L. (South Hadley, MA, US)
Vidich, Charles A. (Ashford, CT, US)
Hennessey, James J. (Clifton Park, NY, US)
Freitas, John C. (Reading, MA, US)
Mueller, Douglas M. (Fort Washington, PA, US)
Application Number:
12/153096
Publication Date:
12/18/2008
Filing Date:
05/14/2008
Assignee:
United States Postal Service
Primary Class:
International Classes:
E02D31/00
View Patent Images:
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Other References:
"Technologies for the stabilization of elemental mercury and mercury-containing wastes", 2010, GRS-252, pages 1-55: http://www.unep.org/chemicalsandwaste/Portals/9/Mercury/Documents/PartneshipsAreas/grs_252_stabmerc.pdf
"Mercury Information and Small Spill Cleanup", HCPHES, 2010, pages 1-5.
Aucott et al. "Release of Mercury From Broken Fluorescent Bulbs", Environmental Assessment and Risk Analysis Element, February 2004, pages 1-5.
Iosson, "Clearing up spills of metallic Mercury", The University of Reading Health & Safety Services - Safety Note 32, 2004, pages 1-4.
Primary Examiner:
GAKH, YELENA G
Attorney, Agent or Firm:
Lewis Roca Rothgerber Christie LLP (Glendale, CA, US)
Claims:
What is claimed is:

1. A method for safely removing mercury released from one or more broken fluorescent light bulbs, comprising: determining an amount of released mercury present at a spill site; comparing the amount of released mercury to a threshold amount of mercury; and if the amount of released mercury is less than or approximately equal to the threshold amount of mercury, removing the released mercury.

2. The method of claim 1, wherein the step of removing the released mercury comprises: containing the released mercury to the spill site; collecting the released mercury from the spill site; disposing of the released mercury.

3. The method of claim 1, wherein the threshold amount of mercury is approximately equal to an amount of mercury contained in four four-foot fluorescent bulbs.

4. The method of claim 1, wherein the threshold amount of mercury is less than or equal to approximately 60 mg of mercury.

5. The method of claim 1, wherein determining an amount of released mercury comprises comparing the number of broken bulbs to a threshold number of bulbs determined to result in exposure levels less than a standard exposure level.

6. The method of claim 1, wherein the step of removing the released mercury further comprises donning personal protective equipment.

7. The method of claim 6, wherein the step of removing the released mercury comprises removing the mercury without using respiratory protection.

8. The method of claim 1, wherein, if the released mercury contaminates a permeable surface, the step of removing the released mercury comprises folding the permeable surface so as to enclose the released mercury therein.

9. The method of claim 8, wherein the step of removing the released mercury comprises placing the permeable surface inside a first sealable container.

10. The method of claim 9, further comprising the step of placing the first sealable container inside a second sealable container.

11. The method of claim 1, wherein, if the released mercury is found on a pervious surface, the step of removing the released mercury comprises rolling the affected surface so as to enclose the released mercury therein.

12. A method for an organization to safely clean up mercury spilled from a shattered light bulb at a spill site, comprising: donning proper personal protective equipment; preparing the spill site; collecting particulate mercury and mercury-contaminated debris from the spill site; applying a mercury binding agent to the spill site such that the binding agent reacts with the mercury to form an amalgam; collecting the amalgam from the spill site; placing the particulate mercury, the mercury-contaminated debris, and the amalgam into a first sealable container; storing the first sealable container for disposal.

13. The method of claim 12, wherein personal protective equipment comprises rubber or pvc gloves, goggles or safety glasses, and disposable shoe covers.

14. The method of claim 12, wherein the step of preparing the spill site comprises: evacuating the spill site of individuals not participating in the mercury clean-up; establishing a controlled area around the spill site; containing aerosolized mercury within the spill site; containing particulate mercury and mercury contaminated debris within the spill site.

15. The method of claim 14, wherein the controlled area includes a three-foot buffer around the spill site.

16. The method of claim 14, wherein the step of containing aerosolized mercury comprises shutting interior doors proximate to the spill site.

17. The method of claim 14, wherein the step of containing aerosolized mercury comprises shutting off ventilation to an area including the spill site.

18. The method of claim 12, wherein the mercury binding agent is flowers of sulfur.

19. The method of claim 12, further comprising: placing the first sealable container inside a second sealable container.

20. A method for an organization to safely clean up mercury spilled from a light bulb shattered at one of its facilities, comprising: evaluating an amount of mercury spilled; comparing the amount of mercury spilled to a threshold amount of mercury; and if the amount of mercury spilled is less than or approximately equal to the threshold amount of mercury, employing an employee of the organization to clean up the spilled mercury, wherein the cleaning up of the spilled mercury comprises: containing the released mercury to the spill site; collecting the released mercury from the spill site; and disposing of the released mercury.

21. The method of claim 20, wherein the step of cleaning up the released mercury comprises cleaning up the mercury without the use of respiratory protection.

22. The method of claim 20, wherein the employee of the organization is not exposed to mercury concentrations in excess of OSHA's PEL of 0.1 mg/m3 as an 8-hour time weighted average concentration while cleaning up the spilled mercury.

23. The method of claim 20, wherein the employee of the organization is not exposed to mercury concentrations in excess of ACGIH's PEL of 0.025 mg/m3 as an 8-hour time weighted average concentration while cleaning up the spilled mercury.

24. The method of claim 20, wherein the employee of the organization is not exposed to mercury concentrations in excess of NIOSH's PEL of 0.05 mg/m3 as an 8-hour time weighted average concentration while cleaning up the spilled mercury.

25. The method of claim 20, wherein the employee of the organization has received at least 2 hours of initial mercury work practice training covering the method for safely cleaning up mercury spilled from a shattered light bulb, the health effects of mercury, and reporting procedures.

Description:

TECHNICAL FIELD

The present invention relates generally to methods whereby broken, fluorescent light bulbs can be safely handled for clean-up and, more particularly, to methods whereby a de minimus quantity of fluorescent bulbs of varying type, mercury content, or size, if broken, can be safely handled without contracting an environmental remediation firm.

BACKGROUND

Approximately 620 million fluorescent bulbs are discarded annually in the United States and many of these are broken during disposal. Only about twenty percent of these fluorescent bulbs are recycled. Assuming an estimated mercury content of these bulbs ranging from three to eight milligrams (mg) per bulb, these discarded bulbs account for approximately two to four tons of mercury waste per year. As much of this breakage is uncontrolled, elevated levels of airborne mercury, which is a very persistent chemical in the environment, could be present in the vicinity of the broken bulbs. In some cases, depending on the conditions associated with the breakage, nearby facility occupants might be exposed to airborne levels of mercury in excess of recognized occupational exposure limits.

The Environmental Protection Agency (EPA) has estimated that six percent of the mercury in broken bulbs is released into the air. Oak Ridge National Laboratory has estimated that concentration to be much higher—up to twenty to eighty percent of the mercury in broken bulbs, which may persist for at least a week. In October 2000, a World Health Organization (WHO) report documented nominal background concentrations of mercury vapor in the range of two to ten nanograms per cubic meter (ng/m3) of air, or less than 0.00001 mg/m3 in ambient air. While these ambient exposures are nominal, the occupational exposures in certain industrial settings can be significant. Even low-level occupational exposures can be significantly above ambient mercury levels.

The Occupational Safety and Health Administration (OSHA) sets a mercury Permissible Exposure Limit (PEL) of 0.1 mg/m3 as an eight-hour time weighted average (TWA) concentration. Note that even though the OSHA standards (29 CFR 1910.1000, Table Z-2) indicate that the mercury PEL of 0.1 mg/m3 is a “ceiling” concentration, OSHA clarifications/interpretations dated Jun. 30, 1976 and Sep. 3, 1996 have corrected that to indicate that the of 0.1 mg/m3 is an eight-hour TWA.

The American Conference of Governmental Industrial Hygienists (ACGIH) and the National Institute for Occupational Safety and Health (NIOSH) recommend an eight-hour TWA exposure limit of 0.025 and 0.05 milligrams per cubic meter (mg/m3) of air, respectively, for elemental mercury vapor.

Based on the potential release of mercury during the uncontrolled breakage (no engineering controls, acceptable work practices, or use of personal protective equipment [PPE]) of fluorescent bulbs, potential exceedances of the mercury OSHA PEL may exist. Should bulbs break, there is also the potential that additional mercury could be aerosolized during the clean-up of that debris, especially if conducted in an uncontrolled manner or using an unsafe work practice. This exposure could occur for an extended period of time after the breakage due to the continuing volatilization of the elemental mercury and/or the disturbance of the particulate phase mercury during clean-up.

An organization's maintenance and custodial personnel frequently are involved in the replacement of these bulbs. During bulb replacement, occasional breakage may occur, necessitating clean-up. Also, atypical breakage due to improper storage, inadvertent contact, or other means can result in the need for clean-up of debris that might contain mercury. In one large organization, the U.S. Postal Service (“USPS”), one clean-up involved contracting an environmental remediation firm to assist in that clean-up to preclude elevated or unknown mercury exposures to USPS personnel. This practice is very costly. For example, in one USPS district, a single broken bulb cost $500 for clean-up.

Accordingly, it is desirable to provide a method whereby broken fluorescent bulbs can be safely handled for clean-up internally, as opposed to contracting expensive environmental remediation firms.

SUMMARY

A method for safely cleaning up mercury released from a broken fluorescent light bulb comprises determining an amount of released mercury present at a spill site, comparing that amount to a threshold amount of mercury, and, if the amount of released mercury is less than or approximately equal to the threshold amount, cleaning up the released mercury. The steps of cleaning up the released mercury comprise containing the released mercury to the spill site, collecting the released mercury from the spill site, and disposing of the released mercury.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph depicting mercury exposure over time.

FIG. 2 is a graph depicting predicted versus measured mercury concentrations.

FIG. 3 depicts one exemplary embodiment consistent with the invention.

FIG. 4 depicts further details of the embodiment of FIG. 3.

FIG. 5 depicts further details of the embodiment of FIG. 3.

FIG. 6 depicts further details of the embodiment of FIG. 3.

DETAILED DESCRIPTION

The Negative Exposure Assessment

Based on the ongoing breakage potential, and the costs associated with contracted clean-up, it is desirable to determine if a certain level of mercury clean-up, necessitated by the breaking of one or more fluorescent bulbs, can be performed locally using an organization's internal resources rather than through the contracting of an environmental remediation firm. This assessment requires health hazards associated with those potential exposures to be evaluated in a controlled environment before any such work practices can be developed or performed by an organization's maintenance or custodial staff. This process is termed by OSHA as a “negative exposure assessment,” if the results indicate that there is no adverse airborne exposure in excess of the published OSHA PEL. As such, if successful, future use of the same work practices utilized during the negative exposure assessment study can then be used to conduct future clean-ups, assuming similar work conditions.

Based on bulb usage and breakage information gathered from one organization, the USPS, it was decided to initiate an exposure assessment study based on a maximum of four four-foot bulbs broken. The bulbs selected for the study were General Electric's F34CW/RS/WM, which contains 15 mg of mercury in each four-foot bulb, and Philips F34CW/RS/EW/ALTO, which contains 3.5 mg of mercury in each four-foot bulb. If successful negative exposure assessments could be performed using these two manufacturers' bulbs, then other bulbs containing an equivalent amount of mercury or less would also be covered, assuming the same work practices were used.

Fluorescent bulbs typically contain mercury in varied concentrations, based on size, manufacturer, and age. When these bulbs are broken, the mercury is potentially released in both the gaseous as well as particulate (oxidized mercury in phosphor powder) states. Bulbs are frequently broken during shipment from the manufacturer, during the changing out of bulbs in a fluorescent fixture, and when left in storage (e.g., left leaning against a wall or work surface). For the purposes of the negative exposure assessment conducted, it was assumed that the scenario most likely to result in the greatest spread of breakage debris would involve bulbs falling from a height (e.g., the ceiling) rather than when broken in storage. Therefore, the exposure assessments conducted during these tests involved dropping and breaking bulbs from a typical office ceiling height of eight feet. The assumption was made that the release of vapor and particulate phase mercury would be greatest when the breakage debris was spread widest. Also, in order to simulate a worst-case scenario, the tests would be conducted with the simultaneous breakage of four new bulbs, since newer bulbs contain more liquid mercury than older bulbs, and older bulbs contain more particulate mercury (mercuric oxide) than liquid phase mercury.

The exposure assessment studies were conducted in a controlled environment in order to eliminate the potential release of mercury into the external environment. To this end, test chambers were constructed that could be kept under negative air pressure using high efficiency particulate air (HEPA) filtration systems. Each of the test chambers was approximately twelve feet long, ten feet wide, and eight feet high. The dimensions of the chamber were selected to allow for any debris generated from the bulb breakage to “spread out” in a debris field consistent with a normal breakage pattern and allow enough room for a test subject to work within the test chamber unimpeded. The chambers were constructed of multiple layers of 6 millimeter thick polyethylene sheeting on studded or framed walls. The multiple layers of sheeting facilitated clean-up between studies. After the chamber had been cleaned, the internal layer of sheeting was taken down, rolled into itself, and properly disposed of so as to prevent any potential contamination of the next underlying sheeting layer.

During the course of the test chamber studies, negative air pressure was maintained in the test chamber, but only to the extent necessary to prevent any generated airborne mercury contaminants from escaping the chambers. This minimal negative pressure differential was periodically checked with smoke tubes and documented with a continuous pressure differential recorder. A slight negative pressure maintained the integrity of the test chamber and the cleanliness of the external work area, but had no major impact on the mercury concentration degradation rate that might otherwise result from having too high an air exchange rate in the test chamber. The chamber also comprised a Plexiglas™ viewing window.

Also within the chamber were three mercury vapor analyzers (e.g. three Lumex RA-915 Mercury Vapor Analyzers) used to monitor mercury concentrations within the test chamber, mercury spatial distribution, and mercury concentration degradation over time. These portable real-time analyzers utilize the principle of cold vapor atomic absorption for the detection and quantification of mercury vapor and have a detection limit of 0.1 ug/m3 mercury with a working range up to 100 ug/m3 (100 ug/m3 or 0.1 mg/m3 is the OSHA PEL [eight-hour TWA] for airborne mercury vapor).

Two analyzers were placed at what would be the approximate breathing zones of a subject conducting clean-up of a broken bulb: a first analyzer was placed five feet above the breakage, in the breathing zone of a subject in a standing position, and a second analyzer was placed thirty inches above the breakage, in the breathing zone of a kneeling subject. The third analyzer was placed in the corner of the test chamber in order to determine the concentration of mercury several feet from the bulb breakage. This allowed a “degradation over distance” to be determined. An additional analyzer was placed outside the test chamber to monitor mercury concentrations and assure that there was no transport or leakage of airborne mercury to the outside environment.

During each test, between two and four four-foot fluorescent bulbs were placed inside one of the test chambers and suspended from its ceiling at a height of eight feet. The bulbs were then dropped and broken, there was a five minute waiting period (to simulate the response time of clean-up personnel), and then the mercury vapor analyzers took readings of mercury concentrations within the chamber every thirty seconds for a period of thirty to forty-five minutes.

The exposure assessments conducted were comprised of two types of studies: initial screening studies; and negative exposure assessments. Depending on the results of the initial screening studies, negative exposure assessments could be proposed for bulb types shown not to exceed the OSHA PEL (eight-hour TWA), as indicated by the use of the mercury vapor analyzers.

The initial screening studies were conducted using General Electric's F34CW/RS/WM and Philips's F34CW/RS/EW/ALTO. First, the General Electric bulbs were evaluated in the manner described above, using between two and four of the four-foot bulbs. Next, the Philips bulbs were similarly evaluated, using two four-foot bulbs. The results from one of the Philips screenings is depicted in FIG. 1.

Based on the results of these tests, which indicated that the airborne mercury concentrations were well below the OSHA eight-hour TWA PEL of 100 ug/m3, it was then decided to conduct a series of negative exposure assessments using two of the Philips bulbs under previously determined worst-case conditions. If successful, the results of these tests could then be extrapolated to ensure the work practices used could be applied for a variety of bulb types, bulb quantities, mercury amounts, and working conditions.

The negative exposure assessments were conducted in a similar fashion to the initial screenings with the addition of personal exposure sampling utilizing NIOSH Method 6009. A direct comparison to the OSHA PEL could then be made and a valid negative exposure assessment documented. The personal exposure sampling was conducted using battery-operated sampling pumps connected to a sorbent resin tube (for detection of vapor phase mercury) in series with a thirty-seven millimeter mixed cellulose ester filter sampling cassette (for detection of particulate mercury). A pair of these devices were placed on the subject conducting the clean-up work practice, one on each of the subject's shoulders. A third device was placed in the corner of the test chamber.

The work practice evaluated resulted in an exposure assessment for the maintenance worker conducting that work practice. That actual mercury exposure was then compared to the OSHA eight-hour TWA PEL to determine if an exceedance occurred or was likely for the work practice. Based on the analysis of the airborne samples collected during the course of the evaluation of the work practice, there were no exceedances of the OSHA eight-hour TWA PEL. Therefore, the maintenance work practice performed, and the resultant mercury exposures that were determined, serve as evidence of a negative exposure assessment for the work practice. This negative exposure assessment satisfies the requirements of OSHA and indicates that interim protection measures, such as respiratory protection, are not required for this work practice.

Table 1 summarizes the NIOSH Method 6009 analytical results for the five negative exposure assessment test repetitions conducted using two four-foot Philips fluorescent bulbs.

TABLE 1
Negative Exposure Assessments - Philips Bulbs
Negative8-Hour
ExposureEmployeeCollectionTWAOSHA
AssessmentSampleorTimeResultsResultsPEL
No.NumberLocation(minutes)Analyte(ug/m3)(1)(ug/m3)(2)(ug/m3)(3)
1
shoulder 1NEA-1TEmployee A31Mercury201.3100
NEA-1F
shoulder 2NEA-2TEmployee A31Mercury191.2100
NEA-2F
corner ofNEA-3TEmployee B32Mercury<9<0.6100
testNEA-3F
chamber
2
shoulder 1NEA-4TEmployee A33Mercury241.7100
NEA-4F
shoulder 2NEA-5TEmployee A33Mercury241.7100
NEA-5F
corner ofNEA-6TEmployee B34Mercury<9<0.6100
testNEA-6F
chamber
3
shoulder 1NEA-7TEmployee A39Mercury252.0100
NEA-7F
shoulder 2NEA-8TEmployee A39Mercury262.1100
NEA-8F
corner ofNEA-9TEmployee B42Mercury<7<0.6100
testNEA-9F
chamber
4
shoulder 1NEA-10TEmployee A31Mercury281.8100
NEA-10F
shoulder 2NEA-11TEmployee A31Mercury281.8100
NEA-11F
corner ofNEA-12TEmployee B31Mercury<10<0.6100
testNEA-12F
chamber
5
shoulder 1NEA-3TEmployee A32Mercury<10<0.6100
NEA-13F
shoulder 2NEA-14TEmployee A32Mercury302.0100
NEA-14F
corner ofNEA-15TEmployee B36Mercury<8<0.6100
testNEA-15F
chamber
(1)ug/m3 = micrograms per cubic meter
(2)Eight-hour TWA assumes no further mercury exposure for the balance of an eight-hour work shift
(3)PEL = Permissible Exposure Limit of 100 ug/m3 is an eight-hour TWA
Note 1:
F = filter;
T = tube (all filter analytical results were below method detection limits)
Note 2:
Results preceded by “<” are below the detectable limits of NIOSH Method 6009

A total of thirteen clean-up simulations were conducted for the General Electric and Philips bulb types: five initial screenings using between two and four of the General Electric bulbs; three initial screenings using two of the Philips bulbs; and five negative exposure assessment tests using two of the Philips bulbs (the results of which are reflected in Table 1).

A statistical analysis of the data was desired to determine the validity of the mercury vapor analyzer data, gathered during the initial screenings, versus the NIOSH Method 6009 data, gathered during the negative exposure assessments and the measurement method used by OSHA to determine compliance with the mercury PEL. If there was a good correlation between the analyzer data and the NIOSH data, then extrapolations could be made to the initial General Electric data where NIOSH sampling had not been performed.

Ten of the simulations were chosen for the statistical analysis. These included the initial five General Electric bulb studies, plus the five Philips bulb studies when the NIOSH 6009 methodology was used in conjunction with the analyzers. The initial three Philips screening studies were not used as they were well represented by the previously mentioned five Philips bulb negative exposure assessments.

The paired analyzer and NIOSH 6009 data from the Philips studies were analyzed by statistical methods (regression analysis) to estimate a straight-line relationship between analyzer measurements and NIOSH 6009 measurements. The resulting relationship was applied to the analyzer measurements from the simulations where NIOSH 6009 measurements were not obtained (General Electric studies), in order to estimate expected NIOSH 6009 measurements. Upper and lower confidence limits (95% confidence level) were then calculated for each NIOSH 6009 value. Finally, the NIOSH 6009 values and their 95% upper confidence limits (95% UCL) were translated into eight-hour TWAs for comparison to the OSHA PEL for mercury. The eight-hour TWAs were computed assuming one mercury clean-up per day.

The analysis results are shown in Table 2.

TABLE 2
Statistical Analysis of Exposure Study Data
95%
UCL 8 hr
Mercury95%95%TWA as
# ofVaporNIOSHNIOSHUCLUCL for% of
bulbsAnalyzer60096009(NIOSH8 hr8 hrOSHA
Exp.brokenTWAMeas.Pred.Pred.)TWATWAPEL
Philips2 bulbs16.9619.519.9127.331.241.711.7%
NEA #1
Philips2 bulbs24.192423.8230.881.511.962.0%
NEA #2
Philips2 bulbs21.9625.522.6229.641.772.322.3%
NEA #3
Philips2 bulbs33.872829.0737.691.792.322.3%
NEA #4
Philips2 bulbs15.4417.519.0826.751.231.731.7%
NEA #5
GE4 bulbs48.5037.0050.415.096.936.9%
Screen
#1
GE4 bulbs43.1534.1045.572.172.902.9%
Screen
#2
GE2 bulbs3.2312.5323.480.561.051.1%
Screen
#3
GE2 bulbs24.9124.2131.311.822.352.3%
Screen
#4
GE2 bulbs79.5853.8579.893.655.415.4%
Screen
#5
Measurement Units: micrograms per cubic meter of air (ug/m3)
OSHA PEL = 100 ug/m3 TWA

Each row contains data for one of the ten simulation trials. The first two columns describe the simulations. The third column displays the TWA calculations based on the analyzer data. The fourth column has the NIOSH 6009 measurements (Philips study data). Regression analysis was applied to the data in the first five rows of columns three and four and used to calculate the predicted values in column five, and the regression analysis routine computed the corresponding confidence limits. The eight-hour TWA and eight-hour TWA confidence limits were then calculated assuming only one such exposure per eight-hour workday. FIG. 2 displays measured analyzer and predicted NIOSH 6009 mercury values and their 95% confidence limits for the General Electric bulb studies.

As shown in Table 2 column 7, the eight-hour TWAs for exposure to airborne mercury during clean-up of broken fluorescent bulbs were well below the OSHA eight-hour TWA PEL for mercury. In fact, the eight-hour TWAs were also well below the NIOSH and ACGIH recommended eight-hour TWA exposure limits. The 95% UCLs, which may be interpreted as upper bounds for exposure, are also a small fraction of the OSHA PEL. The largest eight-hour TWA exposure is less than seven percent of the PEL (Table 2, last column).

Therefore, based on the data analysis and correlation between the two testing methodologies for the Philips bulb studies, a similar correlation was shown to be evident for the initial General Electric screening studies. Since this statistical analysis for the General Electric bulbs showed no potential for exceedance of the OSHA eight-hour TWA PEL for mercury (using up to four 15 mg mercury bulbs), the General Electric data would then be representative of valid negative exposure assessments for the work practices utilized.

Airborne mercury exposures when cleaning up four or fewer broken four-foot fluorescent bulbs approached ten percent of the mercury PEL. At least partially based on the above information, a method for handling and cleaning up broken fluorescent lamp spills is set forth.

EMBODIMENTS

Disclosed herein are various methods and devices for safely cleaning up a mercury spill resulting from the breakage of one or more fluorescent light bulbs. Generally, the method includes determining the amount of mercury spilled, i.e., the number and size of the fluorescent bulbs broken, acquiring the proper clean-up equipment, donning personal protective equipment (PPE), preparing the spill site for clean-up, removal of mercury and mercury contaminated items, disposal of mercury and mercury contaminated items, and post-clean-up washing.

Reference will now be made in detail to exemplary embodiments consistent with the invention, examples of which are illustrated in the accompanying figures. Wherever possible, the same reference numbers will be used throughout the figures to refer to the same or like parts.

Referring now to FIG. 3, there is shown one embodiment of a method for conducting clean-up of a mercury spill comprising the steps of ascertaining the amount of mercury spilled, making a determination as to whether a third party environmental remediation firm needs to be contacted, and, if not, taking the proper steps to clean up the spill safely, without exposing those conducting the clean-up to harmful levels of mercury, and preventing further aerosolization of the spilled substance.

In one aspect, the method includes a determination as to the amount of mercury spilled (100). In one embodiment, such a determination may be made by determining the length and number of fluorescent bulbs broken. This can be achieved in various way including visual inspection of the spill site, i.e., counting the number of bulbs broken, or, in the event the number of bulbs broken cannot be ascertained in this fashion, interviewing someone present at the site at the time of the spill or counting the number of intact bulbs present at the site and subtracting this number from the number of intact bulbs that should be present.

Once the number and length of bulbs has been determined, a decision can be made as to whether to contact a third party environmental remediation firm (200). The negative assessment study, discussed in detail above, was successful for up to four four-foot bulbs each containing up to 15 mg of mercury. As a result, in one aspect, where the mercury spill involves more than the equivalent of four four-foot bulbs, the subject conducting a clean-up method consistent with this invention should contact a remediation firm (300). In another aspect, where the spill involves four four-foot fluorescent bulbs or less, the individual(s) conducting the clean-up can continue conducting the mercury clean-up without the aid of a contracted party.

Where the nature of the spill allows for the subject to clean up the mercury spill without the aid of an environment remediation firm, the subject may first don proper PPE in order to conduct the clean-up (400). In one embodiment, proper PPE can include, but is not necessarily limited to, rubber or pvc gloves, goggles or safety glasses, and disposable shoe covers. In other embodiments, the gloves may be comprised of another material or the subject may wear an apron or other protective covering while conducting the clean-up. In other embodiments, the subject is not required to use a respirator or other respiratory protection while conducting the method disclosed herein. He or she may also remove all metal jewelry prior to commencing the mercury clean-up.

In another aspect, the subject performing a method consistent with the invention can prepare the work area affected by the mercury spill prior to commencing clean-up (500). In one embodiment, this can involve gathering supplies necessary to contain the mercury spill and prevent others from entering the site. The supplies needed can include, but are not limited to: safety cones, barrier tape, polyethylene sheeting, non-corrugated cardboard, a dust pan, a brush, broom, or squeege, a spray bottle filled with water, disposable mercury wipes, sealable plastic disposal bags, a bucket with a lid, a flashlight, duct tape, and flowers of sulfur.

FIG. 4 depicts the steps included in preparing the spill site in one embodiment consistent with the invention, including evacuating other personnel and bystanders from the spill site (510), establishing a controlled area around the spill (520), preventing the spread of aerosolized mercury (530), and containing other mercury contaminated debris within the site (540).

In one aspect, the subject conducting the mercury clean-up can evacuate the affected work area so as to prevent others from coming in contact with the mercury and also to prevent the unnecessary spread of mercury or mercury contaminated items that may result from others coming in contact with the spill site (e.g., mercury carried from the site on the sole of a shoe, etc.) (510). In one embodiment, after the area has been evacuated, one can establish a controlled area around the spill, thereby preventing others from entry into the spill site prior to completion of the clean-up procedure (520). This establishment of a controlled area can be accomplished in a variety of ways including sealing the area off using barrier tape. In one embodiment, a barrier of at least three feet around the spill site should be erected. In another embodiment, the subject conducting the clean-up can use barrier cones to demarcate the spill site or alert others to its presence.

In another aspect, it can be desirable to further isolate the spill site by preventing aerosolized mercury from spreading to other areas of a building through the air (530). In one embodiment, where the spill occurs in a small room, ten by twelve feet, for example, the subject conducting the clean-up can close all interior doors and open all windows and exterior doors. In other embodiments, where the spill occurs in large rooms, the ventilation or air conditioning system in communication with the site can be turned off to prevent the further spread of aerosolized mercury to other parts of the facility.

In one aspect of the clean-up method described herein, the subject conducting the clean-up can also contain the particulate mercury present at the spill site from spreading therefrom (540). This can be achieved, in one embodiment, by preventing particulate mercury from escaping down a drain in the floor at the site (i.e., not flushing the spill site with water or standard cleaning products). In another embodiment, the subject can attempt to prevent the particulates from spreading to cracks and other crevices at the site that may be difficult to clean.

Referring now to FIG. 5, once the spill site is evacuated and properly prepared, the subject conducting the mercury clean-up can begin the process of mercury removal (600). FIG. 5 depicts the steps included in properly removing mercury and mercury contaminated debris from the site. In one aspect, the first step is to determine the types of surfaces affected by the spill (610). Where it is determined that wall-to-wall carpeting or a piece of fabric-covered furniture has been contaminated (620), the subject can contact an environmental remediation firm to conduct the clean-up of that surface (630). On the other hand, where curtains, area rugs, or an equivalent fabric or pervious surface are affected (640), the subject can carefully fold or roll the affected surface up onto itself to enclose the contaminated area. This folding or rolling can trap and contain the mercury prior to disposal of the affected item. Depending on the size and shape of the surface, it may be necessary for two or more persons to properly enclose the area.

In another aspect, where a smooth or impervious surface is affected (660), e.g., a hardwood floor or concrete surface, the subject can first remove all particulate mercury and mercury contaminated debris from the spill site. This can be accomplished in various ways. For example, a broom can be used to sweep up the particulate and debris and a dust pan can be used to contain it. Alternatively, a piece of non-corrugated cardboard, a squeegee, or an otherwise rigid, thin surface can be used to collect or scoop up the particulate and debris. In one embodiment, the subject should collect the mercury contaminated waste beginning at the outside of the spill site and begin working in towards the center of the affected area. In this manner, any particulate or debris disturbed during clean-up is contained within the site and not swept or pushed outside of the contained area. In another embodiment, the subject may use a flashlight to aid in the collection of the debris. By holding the flashlight at various angles with respect to the spill surface, reflections off of small debris, such as small glass shards from the broken bulb(s), can be detected and collected. Small fragments of debris can also be collected by applying duct tape or some other tacky material to the spill site and then removing it with the mercury contaminated waste adhered thereto. In other embodiments, the use of a vacuum during clean-up should be avoided as this may lead to further aerosolization and undesirable spread of the spilled mercury.

In one aspect, once the particulate mercury and mercury contaminated debris has been collected from the spill site, the subject conducting the clean-up can sprinkle flowers of sulfur over the breakage area (680). In one embodiment, the flowers of sulfur are sprinkled by the subject from a standing position. The sulfur powder can then be dampened. This dampening can bind the mercury into an amalgam, halting the release of mercury vapors, and can be achieved in a variety of ways. For example, a spray bottle filled with water can be used to mist the powder. The mercury will then react with the sulfur powder and form an amalgam that can then be collected. In one embodiment, this amalgam collection can be performed by wiping it up using a moist paper towel. In another embodiment, the amalgam can be wiped up using disposable mercury wipes.

FIG. 6 depicts the next step in a method of mercury clean-up consistent with an embodiment of the invention. After the mercury has been collected, all mercury and mercury-contaminated debris can be placed in a container (710). In one embodiment, this container is a rigid, sealable container. In another embodiment, this container is a sealable bag. In other embodiments, this container is airtight. The container can then be sealed so as to confine all mercurial liquids and vapors. Next, this container is placed in a second container (720). In one embodiment, this second container can also be sealable. In another embodiment, this second container is a sealable bag. In other embodiments, this second container is airtight. Again, this second container can then be sealed so as to further confine any mercurial liquids and vapors present.

In another aspect, the tools and materials used in the clean-up process can be disposed of according to the same method employed for the mercury and mercury contaminated debris. In other embodiments, however, some or all of the clean-up tools and materials can be adequately cleaned and decontaminated and need not be disposed of.

The containers containing the mercury and mercury-contaminated materials can then be clearly labeled (730). The label placed on the mercury containing containers can be sufficient so as to alert others as to the contents of the containers and also the danger associated with tampering therewith. For example, in one embodiment, the label may read, “Waste Mercury Containing Lamps” or “Toxic.” In one aspect, the container can then be placed in storage (740). In one embodiment, the containers can be stored in a secure area away from occupants until further disposal can be arranged. In another embodiment, the area in which the containers are stored can be well-ventilated. In other embodiments, a facility's hazardous or universal waste storage area can be used to store the containers.

In another aspect of the method disclosed herein, the mercury-containing containers can then be disposed of as hazardous waste (750). In one embodiment, a disposal specialist can be contacted to arrange for further disposal of the mercury contaminated materials. In another embodiment, a division within the same organization may be contacted. For example, at the USPS, the subject conducting the clean-up or someone else charged with overseeing disposal of the containers can contact their USPS Environmental Compliance Specialist. In other embodiments, a outside firm can be contacted for advice as to the further disposal of the containers. For example, an environmental remediation firm can be contacted to either provide instructions as to further disposal or arrange for the pick-up of the mercury and mercury contaminated materials.

In one aspect, once the mercury clean-up has been completed, the subject(s) who conducted the clean-up can wash any skin that may have been exposed to the mercury (800). In one embodiment, this washing includes washing one's hands and/or arms with soap and water then thoroughly rinsing. In other embodiments, soap and water may be similarly used to clean other skin that was exposed to the mercury during clean-up. In another aspect, all others who were present at the time of the bulb breakage or who may have been exposed to the spilled mercury either at the time of spillage or sometime thereafter can wash any skin potentially exposed to the mercury.

The present invention is not limited to the embodiments disclosed herein. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.