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The Risk Factor 1st Quarter 2008

Tuesday, January 15, 2008
The Risk Factor 1st Quarter 2008 Vapor Intrusion

What is vapor intrusion? Why is it now a concern? Is occupant health affected? Are there risk-assessment criteria?

Vapor IntrusionAccording to the EPA, “Vapor intrusion is the migration of volatile chemicals from the subsurface into overlying buildings. Volatile chemicals in buried wastes and/or contaminated groundwater can emit vapors that may migrate through subsurface soils and into indoor air spaces of overlying buildings in ways similar to that of radon gas seeping into homes.” As with radon, there may not be an odor, so the problem can go undetected for a long time. Odors will only be present after the odor threshold of a volatile chemical is reached.

The concentration of vapors in a building will also vary, based on factors including: volatile chemical concentrations in the soil and groundwater, groundwater depth, time of year, temperature, ventilation within the building, and activities within the building. In a worst case scenario, it is possible that vapors from volatile chemicals in a building will accumulate to concentrations that could cause or exacerbate health problems among building occupants.

Vapor intrusion is a rapidly developing field of science as is policy making by the EPA and various states that have guidelines. The EPA first issued a guidance document called “Evaluating the Vapor Intrusion into Indoor Air Pathway” in December 2001. Since then, states such as New Jersey (October 2005), Delaware (January 2007) and Pennsylvania (October 2002) have also developed guidelines. The guidelines typically include information and requirements for:

  • Site-specific screening
  • Sampling procedures and investigation
  • Evaluation of analytical results
  • Understanding background contamination
  • Remedial action
  • Community outreach

Each of these six areas requires significant scientific/engineering expertise to meet the requirements of the guidelines. In addition to input from hydrogeologists, environmental engineers, industrial hygienists and others, there must also be collaboration with the state regulatory staff every step of the way to ensure that the guidelines are met.

One very important document that is required to be developed is the Vapor Intrusion Workplan (VIW) which details every step and process used to identify where samples will be collected, how they will be collected, how they will be analyzed, how data will be interpreted and much more. The VIW must be approved by the regulators before preceding, as it is the road map that must be followed.

Air sampling within a building is done using Summa canisters with specific regulators/orifices to collect samples over an eight- to 24-hour period of time.

Vapor IntrusionSlab and room samples are collected simultaneously to allow for a comparison of compounds found in the sub-slab air to those found in the indoor air.

The comparison will then identify what, if any, contaminant contribution is being made by sub-slab gases entering the indoor air via vapor intrusion.

Please contact Chris Schneider, CIH, President at 610.524.5525, ext 14, or email to discuss any questions or to request a proposal.

What Smells?

Whenever an unfamiliar odor is perceived within a building, it conjures up a level of concern that the air quality is poor and the air is unhealthy. Odors do not equal unhealthy air. This is rarely the case. Unfortunately, if just one employee believes it, you now have a problem. Legitimate or not, it has to be addressed. If you have ever had an odor issue within your facility, you will know how difficult it is to identify a source and a cause.

This is especially true when the odors are intermittent, or move around from area to area within the building. Please remember that finding the source of an odor and resolving the problem require a well-planned approach and time for implementation.

HINT: Do not do air sampling to identify compounds. Why? Typically, odor-causing compounds have very low odor thresholds and will not be detected by analytical equipment. In other words, in many cases your nose can detect the presence of compounds before sampling can! Some instruments may be used later in the investigation.

What Smells?There are several steps to resolving odor issues. The first is to meet with employees and develop a list of trends and possible sources. With this information, an Odor Event Log is developed for employees to log in characteristics of the odor over several weeks. Input from employees is critical not only because it may be accurate, but also because the process empowers the employees to be part of the solution. Second, review the input from the employees along with the Odor Event Log to identify any possible trends related to day of week, time of day, weather conditions (wind, sun, clouds, humidity, rain, etc) processes in the building, etc. Looking for trends is important, as the release of an odor from an indoor source is generally regulated by a change in its pathway and driving forces. If you cannot identify any trends, review the information with several people including the employees who are affected. At this point you might choose to retain a consultant with significant experience in odor investigation to assist.

What Smells?Third, based on the characteristics of the odor episodes, you should now begin to investigate building systems that could be contributing to the problem. For example, if the odor is sweet or aromatic you might want to look at possible entrainment from outdoors, or for moisture sources under impervious flooring (ceramic, vinyl, etc.), as trapped moisture allows for the growth of bacteria that can release organic compounds.

HINT: Remember to look under and behind walls, flooring and ceilings. You might need to do some destructive removal of materials in order to get to possible sources. Remember, it is as important to rule out sources as it is to find the actual source.

Although most of an odor investigation can be accomplished by looking and smelling, there typically will be a need for instrumentation to measure pressure differentials or to measure certain gases like methane or organic compounds to track down an exact emission point.

HINT: For more information, visit our website at www.1ssh.com and go to the Odor web page under Indoor Air Quality Management. There you will find additional information.

Please contact Harry M. Neill, CIH, Vice President, at 610.524.5525, ext 15, or email to discuss any questions or to request a proposal.

NFPA 70E
It’s Now Effective. Is Your Program

On August 13, 2007, the revisions for the OSHA Electrical Installation Standard, Subpart S, 29CFR 1910.302-308, which were issued on February 14, 2007, became effective. This standard was last updated in 1981. What are the major changes and how might they affect you?

While there was no change to these OSHA standards from 1981 to 2007, there were substantial changes in the National Fire Protection Association (NFPA) standards. The NFPA is the organization that generates the National Electrical Code (NEC). Primary among the changes was the issuance of NFPA 70E: Standard for Electrical Safety in the Workplace, 2004. This standard includes requirements for employers to develop programs, procedures and work practices, and to supply appropriate personal protective equipment (PPE) to protect employees against electrical shock and arc flash hazards.

Key concepts in this standard include:

  • Shock hazard analysis
  • Flash hazard analysis
  • Shock protection boundaries
  • Flash protection boundaries

Why did the NFPA feel the need to generate this standard? Between five and 10 serious arc flash/blast hazards occur each day in the United States. The NFPA felt that selecting and using appropriate arc flash clothing and equipment could prevent the injuries and fatalities associated with arc flash/blast. It also believed that selecting and using the appropriate insulating equipment could prevent the injuries and fatalities associated with electrical shock.

NFPA 70E: It’s Now Effective. Is Your Program?The standard requires that a flash hazard and a shock hazard analysis be done before a person approaches any exposed electrical conductor or circuit part that has not been placed in an electrically safe work condition. The shock hazard analysis determines the voltage to which personnel will be exposed, boundary requirements, and the PPE necessary to minimize the possibility of electrical shock. The shock protection boundaries identified as Limited, Restricted, and Prohibited Approach Boundaries are applicable to situations in which approaching personnel are exposed to live parts. Where it has been determined that work will be performed within the flash protection boundary, the employer shall document the incident energy exposure of the worker. This incident energy exposure level shall be based on the working distance of the employee’s face and chest area from a prospective arc source for the specific task to be performed. Flame-resistant (FR) clothing and PPE shall be used by the employee based upon the exposure associated with the specific task. As an alternative, the PPE requirements can be determined based upon the task to be performed, as shown in Table 3.3.9.1, Hazard Risk Category Classification, of the standard.

No qualified person shall approach or take any conductive object closer to live parts than the restricted approach boundary unless:

  • The qualified person is insulated or guarded from the live parts (insulating gloves or insulating gloves and sleeves are considered insulation only with regard to the energized parts that are being worked on) and no un-insulated part of the person’s body enters the prohibited space, or
  • The live part is insulated from the qualified person and from any other conductive object at a different potential, or
  • The qualified person is insulated from any other conductive object during bare-hand live-line work.

NFPA 70E: It’s Now Effective. Is Your Program?Unqualified persons shall not be permitted to enter spaces that are accessible to qualified employees only, unless the electrical conductors and equipment involved are in an electrically safe work condition. Where any unqualified person is working at or close to the limited approach boundary, the designated person in charge of the work space where the electrical hazard exists shall cooperate with the designated person in charge of the unqualified persons to ensure that all work can be done safely. This shall include advising the unqualified persons of the electrical hazard and warning them to stay outside of the limited approach boundary.

There are numerous other requirements and details in this standard, including the need to develop and use Electrical Energized Work Permits. OSHA has not formally compared each provision of the NFPA 70E-2004 standard with the parallel provision in Subpart S but generally believes the NFPA standard offers useful guidance for employers and employees attempting to control electrical hazards.

For additional detail, see the standard or contact Colin J. Brigham, CIH, CSP, CPE, CPEA, at 610.524.5525, ext. 24, or email.

 

 



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