Ventilation radon

Care must be taken in handling radon, as with other radioactive materials. The main hazard is from inhalation of the element and its solid daughters which are collected on dust in the air. Good ventilation should be provided where radium, thorium, or actinium is stored to prevent build-up of the element. Radon build-up is a health consideration in uranium mines. Recently radon build-up in homes has been a concern. Many deaths from lung cancer are caused by radon exposure. In the U.S. it is recommended that remedial action be taken if the air in homes exceeds 4 pCi/1. 

Some builders prefer to concrete the floor of crawlspaces when site and design conditions permit getting the mix into the crawlspace. If a crawlspace has a concrete slab, for radon-resistant construction, the crawlspace should be treated similar to a basement with the advantage of greater ventilation potential. 

Jonassen, N. and J.P. McLaughlin, The Reduction of Indoor Air Concentrations of Radon Daughters Without the Use of Ventilation,... 

Peaks occur at 9 00 and 10 00 and 13 00. The water has a radon concentration of 55,300 pCi/1. Radon concentration in air is given in Figure 3h. A large pulse of radon is visible from 9 00 to 12 00. These peaks represent radon from the water supply uses discussed below. Radon concentration has a stable slow varying portion at 60 cts. and a sudden peak at 180 cts./.5hr. Using these results, a quantitative test is possible for the dilution of radon in the house. These data can also be examined to find the ventilation time for the house which is about 2 hours for the radon pulse to decline by half. Table II presents various average radon and dose measurements for each house studied. 

In the 1955-56 study the radon measurements were usually taken in the living rooms. The gamma measurements were made in several rooms. All samples were taken before noon. With regard to the ventilation, the houses were divided into two groups one termed "ventilated", where the dwelling had been aired one or two hours before the measurements. The dwellings in the group named "unventilated" had not been aired since the day prior to the measurements. 

Here we have only discussed the concentration of the radon gas. This is because the measurements have been made of this nuclide. However, the health effects are referred to the short-lived decay products. The equilibrium factor depends on the ventilation rate and the particle concentrations. 

The ventilation rate has decreased since the 1950s indicating a higher equilibrium factor and thereby a higher radon daughter increase since the 1950s than the increase of the radon gas concentration. How the particle concentrations have changed is not known. 

Wolfs, F., Hofstede, H., deMeijer, R.J. and Put, L.W., Measurements of radon-daughter concentrations in and around dwellings in the northern part of the Netherlands a search for the influences of building materials costruction and ventilation. Health Phys, 47 ... 

Radon (Rn-222) daughter exposure at home is a potentially significant contributor to background lung cancer rates. In western countries, an increase in the number of energy-efficient homes threatens to increase the exposure of the occupants to radon and its decay products by reducing ventilation rates. This is also true in Japan, especially in winter. Japan is situated in the temperate zone, which results in a rather long hot and humid summer climate. Consequently,... 

The level of radon concentration in the dwellings having their own hot-spring bath is also not high compared with conventional houses or those located close to public hot-spring bath as shown in Table V. This lack of difference may also be attributable to a high ventilation rate in the bath room. 

Attempts of keeping the radon level in indoor air low can either be directed at keeping the radon feed low by reducing the entry of radon (from the soil) or to remove radon (and its progeny) from the indoor air by ventilating with outdoor radon-free or radon-poor air. 

The radon concentration Cr at a given ventilation rate r is theoretically given by... 

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