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The hormesis applied to the Radon risk.

Radon is not a risk in itself, being a weakly radioactive and inert gas (as it is inhaled is exhaled), but becomes a significant contributing cause of the development of lung tumors through its “daughters” (i.e. its decay products: Polonium-218, Bismuth-214, Lead-214), as these are highly reactive and radioactive dust, first attach themselves to thin environmental dusts and then in the mucous membranes of the respiratory system.

Considering the hormetic phenomenon, which represents positive responses to low and very low doses (see article below : “The state of research on hormetic phenomena: the effects of low Radon doses”), we can list the preventive measures required to manage safely the potential risks posed by Radon, then passing from the calculation of a LLE – Loss of Life Expectancy to a GLE – Gain of Life Expectancy:

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The state of research on hormetic phenomena: the effects of low Radon doses

Apparently, the extended development of non-linear theories and laws has not affected the legislative inaction on the “Risk Assessment” in toxicology and radioprotection, where it reigns supreme a linear view of the phenomena and a distorted application of the Precautionary Principle, of which the notorious law LNT (Linear No Threshold) is the emblematic fruit.

It’s worth recalling what the non-linear visions are antiques, just let’s mention Paracelsus (XVI century) “All substances are toxic, only the dose makes the difference between a poison and a medicine.”

Fortunately, the linear approaches have not fully prevented the development of radiotherapy and drug therapies based on the biphasic responses (hormesis), which in hindsight provide valuable experimental confirmation to the validity of the hormetic phenomena, waiting for the scientific world asserts again with pride and consistency of not being subject to socio-political arguments, but only to the scientific method.

In line with this pragmatic scientific approach we should be able to achieve a correct evaluation of the effects of low-dose of Radon.

The inhalation of Radon, and in general the quality of the air breathed indoors, is a topic of particular interest from the health point of view (SBS – Sick Building Syndrome) and by its nature has a relevance that can influence the current settings in the hope that “the consolidation of the knowledge base of hormesis will bring profound changes in many sciences, a revolution dose-response, which, like a tidal wave, change perceptions, principles and activities of toxicological and ecotoxicological (Ormesi: la rivoluzione dose-risposta, Luciana Migliore – Università di Tor Vergata, Roma).

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The concept

“All substances are toxic, only the dose makes the difference between a poison and a medicine.” Paracelsus (XVI century)

.The definition – the hormesis, a biphasic phenomenon

“The hormesis can be regarded as an adaptive function characterized by a dose-dependent biphasic response, which occurs as a result of exposure to a very wide range of stimuli,” Calabrese and Baldwin, 2002

The hormetic responses generally show a slight stimulation at low doses (> 30-60% of control) and inhibition at high doses. In order the “qualitative” definition of the hormesis could be satisfied , must necessarily be present both stimulatory and inhibitory size.

The hormetic response curve can be represented by a parabola, a straight or inverted U in relation to the endpoint in question:

The hormetic response can be induced directly (DSH, Direct Stimulation Hormesis), or be the result of compensatory biological processes, resulting from an initial disorder in the homeostasis (OCSH, Over Compensation Stimulation Hormesis).

.The consequences – the linear view mainly produces three serious consequences

The overcome of the LNT (Linear No Threshold Theory) and the introduction of the hormetic phenomenon  involves fundamental changes to the ecotoxicology as well as for the ‘Ecological Risk Assessment (ERA), but also represents a new era for the development of new curative and preventive therapies.

Reading the graphs, reported below, you can “feel” better the impact of a renewed scientific view, as opposed to the simplified linear approche and the distorted application of the precautionary principle. At center the natural phenomenon with it biphasic curve (hormesis) that shows a decrease in the response (eg. tumors), compared to zero dose, for low levels. At the right and left, the graphs show the two linear simplifications, the first called LNT (Linear No Threshold Theory) suggests an increased response at low and very low doses, the second recognizes a zone of “no evidence of significant effects” until a certain threshold.

The linear view mainly produces three major consequences:

Therapeutic application of the hormetic phenomenon

Not surprisingly, a new and interesting application of the hormetic phenomenon comes from american radiotherapists who have decided, through an interesting approach, to combine a screenning  with a preventive therapy at low-doses on a population at high risk of lung cancer ; the “heavy” smokers aged between 55 and 74 years, provides us a useful result for a correct approach to the risk posed by Radon.

Here below an extract of the article published on the  National Cancer Institute (NCI) website, which documents a 20% reduction in deaths due to lung cancer and 7% of deaths attributable to all cancers (including lung cancer). The search lasted 8 years and has involved a significant sample (53,000 patients) and representative of the population at risk of lung cancer.

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The hormesis applied to the Radon risk

Radon is not a risk in itself, being a weakly radioactive and inert gas (as it is inhaled is exhaled), but becomes a significant contributing cause of the development of lung tumors through its “daughters” (i.e. its decay products: Polonium -218, Bismuth-214, Lead-214), as these are highly reactive and radioactive dust, first attach themselves to thin environmental dusts and then in the mucous membranes of the respiratory system.

Considering the hormetic phenomenon, which represents positive responses to low and very low doses (see article below : “The state of research on hormetic phenomena: the effects of low Radon doses”), we can list the preventive measures required to manage safely the potential risks posed by Radon, then passing from the calculation of a LLE – Loss of Life Expectancy to a GLE – Gain of Life Expectancy:

Main bibliography:

The main goals of ERVs/HRVs, besides the energy recovery, are to ensure air quality and high comfort thanks to:

1. a constant air change, for an optimal oxygenation and elimination of pollutants and airborne particules (if equipped with HEPA filters)
2. a constant and optimal temperature and humidity (22°C, 40-50%), entering continuously a low flow of “fresh” air preheated and humidified (in winter) or cooled and dehumidified (in summer).
3. a  significant noise reduction obtained with a silent ventilation at “closed windows”

The ERV and HRV are complementary technologies because the HRV can operate in extreme conditions of humidity and low temperatures, but recovers only the sensible energy, instead the ERV with its enthalpic core (permeable to moisture = latent energy) allows in the summer to dehumidify the ingoing air from outside using the exhaust but drier indoor air expelled outside, and thereby reduce the air conditioner (AC) consumption, as you know an AC consumes about  2/3 of energy to dehumidify the air and the remainder to cool.

The truth is, the more humid the climate, the more energy is saved by an ERV.

A common misunderstanding though, is that an ERV works as a standalone unit, which is only partly true. If there is nothing keeping the temperature and humidity down indoors, there is no differential in vapor pressure between the air streams, and consequently, no exchange of humidity between the air flows. In short, an ERV should work in concert with a properly sized air conditioner.

There is no point in leaving more than 50% of the energy for the birds, no matter where the technology is used. ERVs does work very neatly, especially in humid areas.

In addition the ERV, in moderately cold climates such as in Western Europe, keeps the indoor humidity at an optimum level (40%) humidifying the outdoor ingoing air that contains very low (absolute) moisture rates [g/m³], thus avoiding the need to consume more energy to humidify the indoor air in winter that often tends to fall below 30%.

We often tend to think that in winter the air is more charge of moisture respect to summer, but the reality is exactly the opposite and we have a confirmation when we dry the clothes in gellide days  even in the absence of sunlight. We feel the frost when the sun goes down, because comes down on the humidity.

In winter, outside absolute humidity can easily be as low as 2 grams per kg air and less (-10°C and 100% RH is equivalent to AbsH of about 2 grams/kg air) which means that if you take that air and heat it, the absolute humidity will be the same but the relative humidity will drop drastically when heated to 20°C.

For example: if outdoor temperature is -5°C and 90% RH, and that air is heated to 20°C, the resulting indoor RH is only 17,6%. One has to keep in mind though, there are several anthropogenic sources of moisture indoors that vary greatly over the hours of the day that may affect indoor air quality negatively. The problems arise if the ERV is “too efficient”, or rather, that the ventilation rate is so low that excess moisture (indoor RH of 70% and above) is not vented but returned with ingoing air from the ERV to add to the indoor air. This is a typical situation where a by-pass could kick in.

Ultimately though, the key is to balance air flow, regeneration and HVAC equipment to optimally suit not only your house, but your way of living. An ERV increase comfort in a cold climate in winter, assuring an optimal RH level (more than 30%) and recovering the total energy (called enthalpy = sensible energy + latent energy (humidity)). Besides too low RH levels (typically less than 10-15%), will result in material issues (eg wood cracks) and health problems such as decreased resistivity to airborne pathogens, dried out humus membranes in throat and nose, itchy skin, irritated eyes and tiredness etc..

Ultimately, I guess my own best recommendation would be to get a couple of loggers for temp and RH (eg Hobo) and do some monitoring of the actual indoor conditions over time. If coupled with weather data, I’m sure you can deduce what’s best for you and your house. In the long run, knowing the house will be your best bet to increase comfort and lower energy bills.

Sorry for the provocative question, but the most of the energy goes outside thru the window, the most of the heat that we produce for heating or the most of the energy used for cooling our home and our offices during the warm months.

Who made the first step towards improving energy efficiency with windows that provide a good insulation and a good seal to air flow, keeps intact the problem raised in the title of this post, having to open the windows periodically to ensure the necessary air exchange for oxygen, and to expel excess moisture especially in bathrooms and kitchen. But let’s not forget the importance to expel the chemical contaminants and the Radon (a radioactive gas) that accumulate in the environment in which we live.

But “how much energy I’m throwing out the window?” A lot, from 40 to 50% of the total energy produced, because is the energy contained in the dry air and in the humidity.

Actually we are able to ventilate the rooms with an ERV (Energy Recovery Ventilation) recovering the total energy (enthalpy =  sensible energy + latent energy contained in humidity) with an efficiency ranging from 80 to 90%, then we can point to no longer throw out the window 30 to 45% of energy consumed.

In winter we can also recover the large amount of energy contained in moisture (latent energy) that is generated in excess during a shower or while we cook, and no longer open the window during a long time.

Calculations on the amount of energy recovered “recycling” the air can be performed simply with simulators, some of which are free applications (will be discussed shortly in a future post).

Bye for now and thank you for joining us on recyclingair.com .

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As our homes become more energy efficient, paradoxically they become more hazardous to our health, because allergens and harmful indoor fumes from paint, plastics, carpets, adhesives, and household products stay trapped inside for long hours by the lack of continuous change of indoor air in our tightly sealed and well-insulated houses.

Polluted indoor air can cause respiratory irritation and worsen allergy symptoms for everyone inside, and let’s not forget the importance of living in a well-oxygenated house.

The solution is an energy recovery ventilation (ERV) with filters for fine dust and pollen.

An incomplete list of indoor air pollutants

Chemical Contaminants

• Scented fabric softener sheets transfer chemicals onto clothing and bed sheets.
• Dry-cleaned clothing can release chemicals into the air after they are brought into the home.
• Burning candles release soot and carbon monoxide into the air despite the common belief candles actually reduce rather than improve indoor air quality.
• Building materials like paints, adhesives, carpets and particle boards all contain chemical ingredients.
• Common household cleaners including bleach, disinfectant sprays, and ammonia-based cleaners release harmful fumes into the air when used.
• Plug-in scented oils and air fresheners can release chemicals into your home, and mask odours rather than improve air quality
• Hobby supplies such as paint and adhesives contain chemicals, sometimes toxic, that may or may not emit a strong odour.
• New furniture and draperies may be treated with anti-stain chemicals and or formaldehyde-based finishes that are released in the air for a period of time when new.
• Tobacco smoke contains many harmful chemicals, including formaldehyde.
• Radon a radioactive gas http://en.wikipedia.org/wiki/Radon: the “Radon is responsible for the majority of the public exposure to ionizing radiation. It is often the single largest contributor to an individual’s background radiation dose, and is the most variable from location to location. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as attics, and basements”.

Biological Contaminants

• Plant pollen, abundant in spring and summer months, enters homes on shoes, clothing, hair, and pets.
• Dust mites produce droppings that are highly allergenic, and a prime cause of asthma attacks.
• Dander is produced constantly from cats and dogs. Pets constantly shed old skin cells (dander) which become airborne and, if not removed from the air, irritate the eyes and nose, or are inhaled into the lungs and cause allergic reactions and respiratory irritation.
• Mold and mildew grow in areas where moist air can’t escape, such as wall cavities and basements. Exposure to mold can cause allergic reactions and respiratory problems. Preventing mold is key to improving indoor air quality, and protecting your home investment, as mold can also cause structural damage to your home.

Source: www.livingbreathinghome.com

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What is the difference between an HRV and an ERV?

The core in an HRV (Heat Recovery Ventilator) transfers heat from one air stream to the other. This is called sensible heat. The term ERV (Energy Recovery Ventilator) is usually used to describe a unit with an enthalpic core that transfers moisture as well as heat from one air stream to the other. This (moisture transfer) is called latent energy.

Is an ERV better than an HRV?

Not necessary,  in very cold climates such as in some areas of North America, an HRV could work better than an ERV. This is because the air inside the home during the winter months will be more humid than the outside air. An ERV would transfer the latent heat (humidity) from the exhaust air back into the incoming airstream. This could aggravate moisture problems and encourage the growth of mold and mildew.

Instead, if the indoor air is too dry (during the winter) for comfort, an ERV can help recovering the moisture and the latent energy.

Besides, in summer the ERV will supply to the home air which is cooler and drier than outside, reducing the work for the air conditioner, and energy savings for you. In fact, about 2/3 of the energy used by the air conditioner system is to remove moisture.