Model to Balance an Acceptable Radon Level Indoors
Round 1
Reviewer 1 Report
This paper focuses on a vital issue of radon concentration for health indoor environment. In general, it is concise and well presented.
Suggestion
1>>Line 24, the authors mentioned both Radon 222 and 226. It would be clearer for readers if these 2 questiones can answer: What are the main
sources of them and why they should be the concerned substance for IAQ?
2>>Line 169, please check the Rm, are they 40, 100, 500 and 1,000 or 400, 1000, 5000, and 10,000?
3>>Line 332, both table 3 and table 4 are interested to the reviewer, however the interpretation is weak.
4>>Line 346, it is quite neccessary to point out moisture challenges when applying a radon barrier. However, it is still unclear especially for heritage buildings, what is the recommended measure to avoid moisture.
Author Response
Response to Reviewer 1 Comments
Point 1: Line 24, the authors mentioned both Radon 222 and 226. It would be clearer for readers if these 2 questiones can answer: i) What are the main sources of them, and ii) why they should be the concerned substance for IAQ?
Response 1: Radium is a decay product of uranium, and is therefore found in all uranium-containing minerals. Radium is a solid. Radium emits intense radioactive radiation of alpha, beta and gamma radiation, and this radiation causes samples of the substance "by itself" to maintain a temperature slightly above ambient. The radiation is also the cause of the substance emitting a faint, bluish light. Radiation from radium was used until the 1950s as an "energy source" in luminescent paints, for use on dials, measuring instruments, in aircraft cockpits and many other places. But in the 1930s, the harmful effects of the substance could be seen in those who worked with this type of luminescent paint. All 25 known isotopes of radium are radioactive, and naturally occurring radium consists of four isotopes, of which Radium-226 is the most widespread with a half-life of 1602 years.
Radon itself is the immediate decay product of radium. Radon is a gas that seeps from the ground into buildings where it affects the IAQ. Radon-222 is one of the rarest elements of the decay product of radium and has a half-life of only 3.8 days. Since uran is one of the most common radioactive elements on Earth, radon will be present on Earth long into the future despite its short half-life. Unlike all other intermediate elements in the aforementioned decay chains, radon is, under standard conditions, gaseous and easily inhaled, and therefore a health hazard. It is often the single largest contributor to an individual's background radiation dose, but due to local differences in geology, the level of exposure to radon gas differs from place to place. A common source is uranium-containing minerals in the ground. Radon can also occur in some ground water like spring waters and hot springs as well as building materials composed from groumnd materials.
After line 28 I like to add: Radium is a decay product of uranium. Radium is a solid as uranium. Since uranium is one of the most common radioactive elements on Earth, radon will be present on Earth long into the future despite its short half-life.
Point 2: Line 169, please check the Rm, are they 40, 100, 500 and 1,000 or 400, 1000, 5000, and 10,000?
Response 2: Line 158 to line 161 defines Rim. The presented theory defines the initial radon contribution at an air change q of 0.1 times per hour. Rm 40, 100, 500 and 1,000 is correct.
Allow me to correct Line 171: ‘0.1 h-1‘will be corrected to ‘0.01 h-1’
Allow me to add to Line 172: The initial radon contribution Rim is defined at the air change q equal to 0.1 times per hour.
Point 3: Line 332, both table 3 and table 4 are interested to the reviewer, however the interpretation is weak.
Response 3: Table 3 and Table 4 was implemented to show to ways using the model presented.
- i) Table 3, from a point where the air-change rate was given (at a air-change rate of 0.5 h-1).
Selecting a membrane (allowing penetration of soil gas with a radon concentration) not to exceed 100, 200, and 300 Bq/m3 as an acceptable radon concentration in indoor air.
- ii) Table 4, from a point where an acceptable radon concentration in indoor air was not to exceed 100 Bq/m3. In this case the change in air-change rates, for a initial radon contribution from indoor materials Rim of 40 Bq/m3 allowes penetration of soil gas with a given radon concentration related to the selected membrane.
Point 4: Line 346, it is quite neccessary to point out moisture challenges when applying a radon barrier. However, it is still unclear especially for heritage buildings, what is the recommended measure to avoid moisture.
Response 3: I aggree, a radon membrane must bee selected according to the durability of the building, especially for heritage buildings, creating a far more robust building, moisturewise, perhaps compromising the IAQ related to the radon level indoor. An acceptable radon concentration in indoor air might be compromised selecting a membarne that create a robust building, moisturewise.
Reviewer 2 Report
The authors presented an article "Model to balance an acceptable radon level indoors".
I must admit I enjoyed reading the article, the topic is current and I find the experiments to be logical and well performed and I believe this article will be a welcome adition to overall knowledge concerning radon in buildings.
However I would like authors to improve Introduction. I find it lacking novel radon data and I think authors should add more references concerning radon in the buildings. Also, authors tend to repeat the same statments over and over again (lines 37-40, 85-88, 90-94).
Also when writing equations, * should be substituted by ∙ sign. Line 165, 207. Rim must have the same formatting throughout the text (R with a subscript im).
Overall, an interesting article.
Author Response
Response to Reviewer 2 Comments
Point 1: Improve Introduction. Authors should add more references concerning radon in the buildings.
Response 1: Radon levels in buildings will be added.
After line 36 I like to add: The radon level indoors in Danish dwellings built before 2018 is 105 Bq/m3. For dwellings built before 1995, the radon level is 106 Bq/m3. For dwellings built between 1996 and 2009, the radon level is 93 Bq/m3, and for dwellings built between 2010 and 2018, the radon level is 58 Bq/m3. Approximately 9% of dwellings built before 2018 have a radon level above 200 Bq/m3. 41% have a radon level above 100 Bq/m3 [1]. In comparison, the radon level in dwellings in Finland is 96 Bq/m3, in Sweden 108 Bq/m3 and in Norway 60 Bq/m3. In addition, the radon level in Germany is 50 Bq/m3, in France 66 Bq/m3 and in England 20 Bq/m3, [2]. In Sweden, Norway and Finland, the limit value for radon levels in newly built buildings is 200 Bq/m3. Norway requires that buildings for permanent residence must be able to activate measures to reduce the radon level, if the radon level exceeds 100 Bq/m3. In England (England, Wales, Scotland and Ireland) the authorities apply an action level of 200 Bq/m3 and a target level of 100 Bq/m3. In Germany, the radon level in a workplace must not exceed 300 Bq/m3 [3]. For other buildings, there is no requirement for the radon level in the indoor air [4]. However, new buildings should be planned and constructed so that the radon level does not exceed 100 Bq/m3.
Reference:
[1] Rasmussen, T. V. (2019). Comply of radon protection in homes; in Danish. SBi-Report; No. 2019:07. Danish Building Research Institute. Aalborg University. Copenhagen. Denmark. 59 s.
[2] http://www.stuk.fi/sateilyymparistossa/radon/sv_FI/pitoisuudet/.
[3]http://www.bgbl.de/xaver/bgbl/start.xav?startbk=Bundesanzeiger_BGBl&jumpTo=bgbl117s1966.pdf
[4] https://lfu.rlp.de/de/arbeits-und-immissionsschutz/radoninformationen/
Point 2: Authors tend to repeat the same statments over and over again (lines 37-40, 85-88, 90-94).
Response 2: I will delite line 39-40, To effectively lower the air pressure at the lower zone of the ground slab, the ground slab itself must be sufficiently airtight.
Point 3: Also when writing equations, * should be substituted by ∙ sign. Line 165, 207. Rim must have the same formatting throughout the text (R with a subscript im).
Response 3: Will be corrected:
Equation (1): K ∙ u = F,
Equation (2): q ∙ A ∙ h ∙ Rpv = y ∙ r + x ∙ Rg,
Equasion (5): x + y = q ∙ A * h.
Correct Line 156, 165, 185, 202, 2078, 208, 335, 337, 344, 420: ‘Rim’ to ‘Rim’
