ABOUT US BRANDS SERVICES NEWS PROJECTS CONTACTS
 
 
    ARM | RUS
Fogging
  1. Introduction
 Fogging is a phenomenon that became known at the start of the eighties, with research taking place on it from the mid-nineties. A conclusive scientific explanation has still not been found for this phenomenon, which only occurs in the winter months in periods when interior spaces are heated.

2. What fogging is
 Fogging is a phenomenon where in new or just renovated homes black marks originate in the winter on structures including walls, windows, curtains and electric switching material. This is not normal soiling that originates in the course of the years, but soiling that appears in a few days or weeks, often disappearing in the summer, and usually returning the following winter.

3. Provisionally identified causes
 In 1997 the Institut fur Wasser, Boden und Lufthygiene of the Umweltbundesamt in Germany carried out an investigation of 132 cases of fogging. The following appeared from this research:
  • In 90% of all cases fogging only occurred in the winter in the heating period.
  • All homes were newly built or had recently been renovated.
  • The dark marks usually disappeared in the following summer, to often return again the following winter.
    The analysis of the deposits showed no indications of deposits of combustion residues (analyses for soot and PAH were negative). What usually were found were high-boiling organic compounds such as softeners, long-chain alkanes, alcohols and carboxylic acids.
 The research institute formulated the possible causes of the phenomenon as follows:
 With the construction or renovation of homes, different products are used that contain high-boiling organic compounds (semi-volatile organic compounds: SVOC's) that are emitted by volatising to the inner atmosphere. Examples of such materials that come to mind are laminate, PVC, carpeting materials, plastic panels, etc. The concentrations of these compounds usually increase greatly in the winter, with the heating on and without the good ventilation of the spaces. The SVOC's adhere to the micro dust particles present (< 45 µm) that in certain circumstances deposit on surfaces.
 The SVOC's in the air are indeed the most important but not the only cause of fogging. Other factors that play a part are:
  • Constructional factors (heat bridges and condensation surfaces);
  • Utilisation of the space (the absence of ventilation);
  • Other emission sources of SVOC's such as oil lamps or candles)
  • Climatic conditions such as air humidity which influence the extent to which particles can electrostatically charge in the air;
  • The thermal conditions in a space, the presence of electrostatically charged surfaces and the presence of a large temperature gradient between the inside and outside environments also determine the occurrence of fogging.
4. To the extent now known, which substances and products are responsible for the origination of fogging?
 The so-called SVOC's (semi-volatile organic compounds) as well as highly volatile organic compounds play a part in the occurrence of fogging. With chemical analyses of the deposits occurring with fogging, chemicals including the following are found:
  • Alkanes with long chains - Heptadecane to Pentatriacontane (C17 to C35)
  • Fatty alcohols - Tetradecanol, Hexadecanol, Octadecanol
  • Fatty acids - Palmitic acid, Stearic acid, Oleic acid, Linoleic acid, Linolenic acid
  • Fatty acid esters - Methyl palmitate, Methyl stearate, Butyl palmitate, Cetyl palmitate, Stearyl palmitate
  • Phthalic acid esters - Dimethyl, Dibutyl, Diiso-butyl, Benzylbutyl, Bis(2ethylhexyl)-and Dioctyl phtalate
  • Others - Adipates, Sebacates, Triterpenes, Terephthalates, Squalene, Polyethyleenglycols, Siloxanes.
    When combustion processes have contributed to fogging, PAH's (polycyclic aromatic hydrocarbons) and/or soot (elementary carbon) are also found in the deposits. An analysis of the presence of PAH's in the deposits can therefore demonstrate if emissions from combustion processes have played a part in the occurrence of fogging.

5. Which factors play no part in the origination of fogging?
 Besides the factors that possibly play a part in the origination of fogging, it was also examined to see which factors do not play a part.
 The following factors play no part of any significance in fogging:
  • Emissions from traffic, industry or other external factors.
  • The nature of the heating, as fogging occurs with all heating systems.
  • Smoking.
  • Non-excessive burning of fossil fuels.
6. Precautionary measures
 Fogging can be avoided by using low-emission or emission-free materials. The reducing or prevention of the release of SVOC's is indeed of decisive importance. More and more manufacturers are responding by marketing so-called non-fogging materials. Renovations can the best take place in the spring, so the greatest emissions of SVOC's have ended at the start of the heating season.

7. Effects on health
 Health risks can only be associated with the concentrations of hydrocarbons harmful to health, and are otherwise not related to the phenomenon itself. 8. Preventive methods
 The black deposit is difficult to remove using cleaning products. Without removing the cause, the removal of the deposit does not help at all. In individual cases it has been observed that changing the type of carpet, laminate floor, wall panels etc. stops the black marks. Painting over with solvent-free paint that is not a softener and accordingly SVOC-free does not usually suffice because the source of the SVOC is not removed.
 Other preventive measures mentioned by various authors concern:
  • Thorough ventilation
  • Extra heating
  • Removing SVOC sources (special softener-containing building materials such as PVC, panels, latex paint)
  • Not using candles and oil lamps
9. Worthwhile and not worthwhile analyses with fogging
 Once fogging has been diagnosed there is usually little point in carrying out all sorts of other examinations and analyses. A precise scientific explanation of the cause is on the one hand not fully available, and on the other hand not a complete requirement. Furthermore, the costs of the necessary chemical analyses often amount to a multiple of the total cost of renovation. The rectification measures do not change at all if it is known that the discolouration is caused by phthalic acid esters or by octadecanol. Analyses are only worthwhile if the cause can be more precisely located as a result. Is the only cause the carpet or also the latex paint? More specific analyses can sometimes determine the source of the SVOC, but this is often also known without chemical analyses. Random analyses are certainly associated with considerable costs, while the results do not always give a clear indication of the cause.

10. Developments concerning fogging
 An increasing number of SVOC's, solvents, fire-retarders and softeners are currently being examined to see if they may cause fogging. Special fogging testers have been developed for test laboratories for this purpose. As a logic consequence of this, an increasing number of anti-, non-, or low-fogging products are appearing on the market.Another development is taking place in the field of surface technology. Research is taking place on an extensive scale into hybrid organic and inorganic coatings that prevent fogging by their anti-static, anti-adhesive effects.

11. Conclusion
 The exact mechanism that causes fogging is still unknown. The cause appears to be heating causing the release of one or more of the following, moderately volatile substances: softeners, fire-retarders, SVOC's, PAH's, etc. Under the influence of certain temperature gradients, or a certain degree of humidity, as a result of the presence of fine substances and electrostatic charging, circumstances can occur which cause the coagulation of organic substances with the fine substance, with this precipitating and depositing on surfaces in homes.

Back
 
 
   
  15, Vardanants str., Yerevan 0010
  Tel. (374 10) 51 61 15, 54 83 15
  info@termoros.am