Radon, radioactive

CAS RN: 10043-92-2

Other Preventive Measures

Control of radon and its daughters is accomplished generally by ventilation.
/WORKPLACES OTHER THAN MINES/ It is likely that surveys will be necessary to assess the geographical variation of radon exposure in buildings and the variations in radon levels between different types of work activity. Geological considerations will often be a good general guide to identifying areas in which radon levels are likely to be above average. However, there is a complex relationship between geological parameters, such as soil porosity and concentrations of uranium and radium, and levels of radon in buildings.
/WORKPLACES OTHER THAN MINES/ If radon levels are found to be above the action level the employer will need to arrange for remedial measures to reduce radon concentrations to below the action level. This will preferably be a decisive action aimed at a substantial reduction in radon levels, not simply a stopgap measure to edge concentrations below the action level. ... It is expected that remedial measures will normally be successful in reducing radon concentrations to below the action level. Where this is the case, it is advisable that the building be retested at intervals determined by the regulatory body in order to ensure that the remedial measures continue to be effective. The employer needs to perform regular operational checks of the remedial systems to ensure that fans and other equipment have not failed or been switched off. In cases where the radon concentration still exceeds the action level after all practicable remedial measures have been taken, the authorities and/or the employer are required to implement an appropriate scheme for radiation protection ... . In addition to remedial action in existing workplaces, regulatory bodies need to consider adopting a cost effective preventive approach to the control of radon in future workplaces as part of a long term strategy aimed at reducing exposures to radon.
/WORKPLACES OTHER THAN MINES/ For foundations and basements in contact with soil, the most effective mitigatory measure is to reduce the pressure of the soil gas in the vicinity of the foundation relative to the pressure in the structure. This reverses the normal situation in which the indoor air of buildings is generally found to be at an underpressure with respect to the subjacent soil gas.This pressure reversal may be accomplished by installing a system of pipes leading from the soil or aggregate under the foundation to a fan that maintains a negative pressure gradient between the soil and the foundation.The approach effectively reduces the amount of radon entering the structure by reducing the amount of soil gas entering. The soil gas containing radon can then be vented harmlessly to the atmosphere.Where possible, it is desirable to install a small and simple cavity or sump within the foundations to which the system of pipes may be attached. For buildings with extensive and complex foundations a number of such depressurization systems may be needed for effective radon control.
/WORKPLACES OTHER THAN MINES/ If the ground floor is not in contact with soil, an effective mitigatory measure is to ventilate the space beneath the floor. This may be accomplished by increasing natural ventilation or by installing a fan that removes the radon laden air from under the floor and replaces it with outdoor air. The approach effectively reduces the amount of radon entering the structure by reducing the concentration of radon in the air beneath the floor.
/WORKPLACES OTHER THAN MINES/ The cracks and other openings through which radon enters the structure may be sealed. This method is considered less effective than sub-floor depressurization because it is difficult to seal all entry routes adequately and because seals tend to deteriorate over time. This method is likely to be ineffective unless all the cracks are sealed. It can be used as a supplementary measure to increase the effectiveness of sub-floor depressurization or sub-floor ventilation. At the construction stage of a building, heavy duty plastic membranes incorporated into the foundations may act as effective radon barriers provided that they are properly sealed at jointing and are not punctured during installation.
/WORKPLACES OTHER THAN MINES/ Radon in indoor air may be diluted by increased ventilation of the indoor spaces with outdoor air.This method can be costly in terms of energy loss, particularly in cooler climates. Energy loss can be reduced by using heat exchangers but these have significant purchase, operating and maintenance costs. In some structures, increased ventilation can actually result in an increase in indoor air radon levels by causing an increase in the underpressure of the indoor air with respect to the subjacent soil gas. For these reasons, ventilation as a method of reducing indoor radon levels is to be used with caution.
/WORKPLACES OTHER THAN MINES/ Elevated levels of radium in the soil underneath or surrounding a building can be the cause of increased radon levels in the indoor air. Removal of the subsoil and replacement with uncontaminated soil has been shown to be effective in lowering radon levels indoors. Since this method represents a major undertaking, it is only used in exceptional circumstances.
/WORKPLACES OTHER THAN MINES/ If the water used in a workplace is a significant source of radon, treatment of the water by aeration or other methods (such as filtration with activated charcoal) to reduce the radon levels prior to use can be effective. In municipal water treatment plants where groundwater with high concentrations of radon is processed, aeration of the water may give rise to very high air concentrations of radon within the plant. In this case strong ventilation of the air spaces of the water treatment plant, coupled with restrictions on working hours for staff, can be effective. In practice staff usually make only periodic brief inspections in the high radon areas of such treatment plants.
/WORKPLACES OTHER THAN MINES/ CONTROL OF RADON EXPOSURES WHEN REMEDIAL MEASURES ARE INEFFECTIVE: Training. In order to prevent human errors which might result in undue exposures, all personnel on whom protection and safety depend need to be trained appropriately.
/UNDERGROUND MINES/ Effective work practices and engineering controls must be instituted by the mine operator to reduce the concentration of radon progeny to the lowest technically achievable limit. ... 1. Ore extraction and Handling: Examples of effective ore extraction and handling procedures include the following: minimizing the number of ore faces simultaneously exposed, performing retreat mining toward intake air, limiting the underground storage and handling of ore, locating ore transfer points away from ventilation intakes, removing dust spilled from ore cars, minimizing ore spillage by maintaining roadways and carefully loading haulage vehicles and covering ore until it is moved to the surface. 2. Blasting should be performed at the end of the work shift whenever possible. Miners must be evacuated from exhaust drifts until environmental sampling confirms that the average work shift concentration of radon progeny does not exceed 1/12 of a working level concentration. The mine operator must not use the planned rotation of miners to maintain an individual's exposure below the recommended exposure limit of 1.0 working level month per year. /Radon progeny/
/UNDERGROUND MINES/ Mechanical exhaust ventilation used alone or in combination with other engineering controls and work practices can effectively reduce exposures to radon progeny. Ventilation systems discharging outside the mine shall conform with applicable local, state, and federal air pollution regulations and shall not constitute a hazard to miners or to the general population. ... Fans shall be operated continuously in the work areas of an active mine and before the opening of a previously inactive mine or inactive section until environmental sampling confirms that the average work shift concentrations of radon progeny do not exceed 1/12 an average work shift concentration. /Radon progeny/
/UNDERGROUND MINES/ The preparation, storage, dispensing (including vending machines), or consumption of food is prohibited in any area where a toxic material is present. /Radon progeny/
SRP: Local exhaust ventilation should be applied wherever there is an incidence of point source emissions or dispersion of regulated contaminants in the work area. Ventilation control of the contaminant as close to its point of generation is both the most economical and safest method to minimize personnel exposure to airborne contaminants. Ensure that the local ventilation moves the contaminant away from the worker.
SRP: Contaminated protective clothing should be segregated in a manner such that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. The completeness of the cleaning procedures should be considered before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at the end of shift, but should remain at employee's place of work for cleaning.
/BUILDINGS/... Measures that can be taken to reduce exposure to radon are described, including replacement of fill, surface coating of building foundations, air filtration and improved ventilation. ...
/BUILDINGS/There are three general categories of techniques for the control of radon and radon progeny concentrations in indoor air: restriction of radon entry, reduction of indoor radon concentrations by ventilation or air cleaning, and removal of airborne radon progeny. The predominant radon entry process in most residences appears to be pressure driven flow of soil gas through cracks or other openings in the basement, slab or subfloor. Sealing these openings or ventilation of the subslab or subfloor space are methods of reducing radon entry rates. Indoor radon concentrations may be reduced by increased ventilation. The use of charcoal filters for removal of radon gas in the indoor air by adsorption has also been proposed. Concentrations of radon associated with radon exposures, can be controlled by use of electrostatic or mechanical filtration. Air circulation can also reduce radon progeny concentrations in certain cases. ... Reviews of the application and limitations of each of these control measures /are also discussed/.
/BUILDINGS/ /In its Citizen's Guide to Radon/ EPA Recommends: Test your home for radon - it's easy and inexpensive. Fix your home if your radon level is 4 picoCuries per liter (pCi/L) or higher. Radon levels less than 4 pCi/L still pose a risk, and in many cases may be reduced.
/BUILDINGS/ /In its Citizen's Guide EPA notes that/ Radon reduction systems /in homes/ work and they are not too costly. Some radon reduction systems can reduce radon levels in your home by up to 99%. Even very high levels can be reduced to acceptable levels.
/BUILDINGS/ New homes can be built with radon-resistant features. Radon-resistant construction techniques can be effective in preventing radon entry. When installed properly and completely, these simple and inexpensive techniques can help reduce indoor radon levels in homes. In addition, installing them at the time of construction makes it easier and less expensive to reduce radon levels further if these passive techniques don't reduce radon levels to below 4 pCi/L. Every new home should be tested after occupancy, even if it was built radon-resistant. If radon levels are still in excess of 4 pCi/L, the passive system should be activated by having a qualified mitigator install a vent fan.
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