MAH_2019

MAH 2019 Companion Guidance Section D Understanding RDP Measurements 9 RADON DECAY PRODUCT MEASUREMENTS—INFLUENCES ON THE EQUILIBRIUM FACTOR (EF) The listing below is illustrative of the effects various activities and conditions can have on the RDP measurement test result. The radon professional should review the circumstances in each house that may be increasing or decreasing suspended radon decay products to determine if those variables are long-term or intermittent in making recommendations to the client . Item Effect on EF Discussion Intermittent Fan Activity such as Ceiling Fans Decrease Low EF as a result of ceiling fan or other intermittently active fans will not likely be representative of other rooms without fans and not likely representative of EF during months without fan activity. Window Air Conditioner Decrease Although window A/C should be in total recycle mode for any test, the air movement when operating can increase plate-out on physical surfaces. Wall mounted split air conditioner or heat pump with blower Decrease Recirculated air from a wall unit can increase plate-out of RDPs to physical surfaces for the room in which it is located. A test in such a roommay not be representative of other rooms, unless wall units are located in all occupied rooms. Portable Circulating Fan Decrease The operation of a portable fan in a given room can increase plate-out within that room which would not be representative of other rooms in the building. Forced Air Unit (Auto) Decreases when blower is ON Blowers of FAUs cause more plate-out when system is calling for heating or cooling. The amount of reduction is dependent upon frequency of use. Forced Air (Constant ON) Decrease Increased air circulation will cause more RDPs to attach to physical surfaces. Modular air cleaners (Stand-alone) Decreases in room it is located within Air cleaners can significantly reduce EF due to: 1.) increased air movement, and 2.) removal of other suspended particles to which RDPs are attached. Low EFs in a room with an air cleaner will not be representative of other rooms in building. Whole House Air Cleaners Decrease Whole house air cleaners can be stand-alone with their own ductwork system or incorporated into a forced air heating/cooling system with the blower running constantly at a low speed for air borne particulate and allergen removal. Vacant Building Variable The absence of furniture in a building can decrease surfaces to which RDPs can attach. Conversely the absence of occupants can reduce use of air handling equipment. Non-Forced-Air heating system Increase Buildings with radiant style heating systems have lower air movement and hence lower attachment of RDPs to physical surfaces. Intermittent Particulate Releases Increases Activities that release particles into the air can increase EF during periods of release. Examples: • smoking, • vacuuming, • burning candles, and • use of fireplace or unvented combustion appliances Longer-Term Particulates Increase High particulate levels in outdoor air can increase indoor particulate levels. Examples: • smoke from fires in the area, and • buildings located in regions of high smog and elevated PM-2.5 plus levels. Clean outdoor air Decrease Areas where smog and outdoor particulate levels are very low, such as non- industrialized coastal areas can have low EF. High Humidity Increase High humidity can provide airborne water droplets to which radon decay products can attach (similar to dust particles). Attachment to water vapor can also neutralize charge of RDPs causing them to be less likely to plate out on physical surfaces. Test device near charged surfaces Decrease Charged surfaces such as CRT monitors and TV screens that create localized static charges can attract RDPs near them.