The chemistry of living: health, well-being and the avoidance of indoor pollutants are inextricably linked. A perfect indoor climate and good indoor air always have a positive effect on human well-being and health and also increase performance. The avoidance of indoor pollutants can be significantly influenced by yourself.
Text Peter Tappler
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Indoor climatology
In the past, indoor air pollution was only given a certain amount of attention in Austria relatively late in comparison to outdoor air pollution, and then usually only in specific cases (e.g. caused by passive smoking, radon, gas stoves or air conditioning systems). Only workplaces where harmful substances are used have been regulated in detail for some time. Only in recent years has the issue of indoor air pollution received increased attention, not least because comparative studies have shown that exposure to air pollutants can also be relevant in non-commercial indoor spaces. If pollutant sources are present indoors, the pollution can exceed that in the outdoor air many times over.
In our culture, people spend a large proportion of their time indoors. The quality of indoor air is particularly important for small children, sick people and other more sensitive groups of people due to the comparatively long time they spend indoors. In addition to its direct toxicological significance, it has an important function for the quality of living and quality of life, which is why properties that impair people’s well-being and are a nuisance (e.g. unpleasant odors, the indoor climate) must also be taken into account. In addition, the function of the living environment as a recreational space must be taken into account, for example in the event of stress at the workplace.
Illnesses, impairments and symptoms that can be caused by indoor pollutants often have complex causes and are usually not clearly attributable to a specific factor. Therefore, the presence of certain symptoms in residents is not a sufficient indication of the pollutant or even the pollutant group. Many symptoms are also “unspecific” in the sense that they cannot be caused solely by indoor pollution, but by a variety of other factors.
Temperature and humidity
Temperature and humidity as factors that can be directly perceived by people are a central area of indoor climatology. Limit values are defined for temperature in labor law, otherwise there are recommendations that determine the optimum range for these parameters in terms of well-being and performance. A BMK position paper examined the situation with regard to the “Effect of energy-saving measures on indoor air” [1]. The graphic by Leusden & Freymark has proven to be very helpful for practical use.
Comfort range according to Leusden and Freymark with building physics upper limit in the cold season
Ventilation and performance
Air pollution also influences performance. It is well established that high performance gains can be expected with better ventilation in offices, schools and classrooms [3]. In densely occupied rooms, mechanical ventilation support is generally necessary in addition to window ventilation. Relatively new is the scientific proof of something that has long been known to attentive sleepers: with good night-time ventilation, you feel better the next day and perform significantly better on average [4].
Carbon dioxide (CO2) has established itself as the central indicator in relation to ventilation since the middle of the 19th century. The so-called “Pettenkofer number” [5] of 1,000 ppm or 0.1 vol% CO2 should not be exceeded on average in rooms “in which mental work is carried out and which are used for regeneration” according to the BMK’s indoor air assessment guidelines [6], otherwise 1,400 ppm is the limit. The concentration of CO2 also acts as an indicator for various other anthropogenic (man-made) volatile substances and odorous substances, which together cause fatigue, reduce performance and therefore contribute to poor indoor air quality.
The recent publication of ÖNORM H 6039 for educational facilities, which sets out the required personal air volume flows, was therefore groundbreaking in terms of ventilation [7]. These requirements cannot be met without mechanical ventilation with heat recovery, without having to accept massive losses of comfort in the classrooms. Exhaust air systems and pure window ventilation, on the other hand, have proven to be unsuitable for schools [8]. In summary, we cannot afford schools without ventilation systems, as the investment for good ventilation is negligible compared to the monetary gains in performance and comfort.
Sources of indoor pollutants
Important sources of indoor pollutants are certain human activities such as cigarette smoking, cleaning activities, combustion processes as well as certain building materials, furnishings or interior materials. High levels of volatile organic compounds (VOCs) continue to be detected in indoor air, particularly after building work. Increased VOC concentrations are created when surfaces are coated or sealed, are emitted from wood and wood-based materials or are newly formed in the material or in the room (e.g. reaction products such as aldehydes). In contrast, many of the problematic substances mostly installed in the 1960s and 1970s, such as formaldehyde, tar products, PCP or PCBs, have become quieter due to the ongoing removal of the installed emitters. One example of this is the carcinogenic fibrous material asbestos, which was even contained in fillers until the 1990s. This is particularly important for occupational safety during the demolition and conversion of buildings.
Keyword carcinogenic: It is little known that so-called “bio-ethanol stoves” release large quantities of benzene and formaldehyde as well as particulate matter into the air [9] – such stoves without a flue should therefore not be used indoors, just like tobacco smoke. In summary, it can be said that the situation has improved considerably for almost all noxious substances – with the exception of the ever decreasing air exchange rate in new buildings.
Are natural materials healthy?
Building with natural materials massively reduces the burden on the environment and is highly recommended from an ecological point of view. Contrary to popular opinion, however, there is no reason to assume that “organic” building materials are generally better for indoor air than “conventional” products. This applies in particular to the use of pine wood in building constructions, which can be a strong source of terpenes, or Swiss stone pine, whose supposedly positive properties have never been scientifically proven.
Bad news for esoterics too: the excessive use of incense sticks, scented lamps and candles pollutes indoor air on a massive scale. The concentration of particulate matter exceeds health-based guideline values.
Legal requirements, standards and other regulations
The OIB guidelines, which form the basis of the statutory building regulations of the federal states, refer to the indoor climate in several places. For example, OIB Guideline 3 [10] stipulates that occupied rooms must be designed in such a way that hazardous emissions from building materials and from the subsoil (i.e. the radioactive noble gas radon) must not lead to concentrations that impair the health of users. OIB Guideline 3 also addresses the issue of preventing flue gases from entering indoor spaces and avoiding water vapor condensation in or on building components (specified in OIB Guideline 6 [11]) – this prevents mold infestation.
Avoiding water vapor condensation in or on building components prevents mold infestation.
Numerous ÖNORM standards, VDI guidelines and, above all, the ISO 16000 series go into more detail. The “Indoor Air” working group set up in 1999 by the then Ministry of the Environment (now BMK) drew up numerous position papers on current topics (including dealing with corona) and defined indoor guideline values on a toxicological basis for numerous volatile substances [12]. The Austrian mold guide [13], published in 2019 together with the German Federal Environment Agency, the AUVA and the Federal Association for Mold Remediation, has now established itself as the standard work for dealing with mold infestation and remediation.
Not to be forgotten are the various building certification systems such as ÖGNB or ÖGNI, whose basis with regard to pollutants is the recently completed ISO guideline 16000-41 [14]. Overall, despite some gaps, there is now a good basis for assessing pollutants and other factors that can also be used for planning processes (e.g. ventilation concepts). The website https:/raumluft.org provides further information on indoor topics.
Compilation of important pollutants and other factors
|
Pollutant/toxin |
Possible effect on humans (dose-dependent) |
Frequent sources/causes |
Remedy |
| Allergens | Allergic asthma, inflammation of the mucous membranes and conjunctiva, rhinitis | House dust, pets, pollen, food ingredients, plants, mold spores | Allergen avoidance, avoid pets, vacuum cleaners with HEPA filters or exhaust air systems, good ventilation, air purifiers |
| Asbestos* | Cancer of the respiratory tract, rib and peritoneal cancer | Sprayed asbestos, seals, floor coverings (“Cushion Vinyl”), fillers, night storage heaters | Have asbestos removed by specialists, use respiratory protection (FFP2 masks) when doing DIY work with fillers |
| Biocides | Damage to the nervous system, headaches, with PCP also liver cancer | Wood preservatives, paints, carpets, pest control (“gel sticks”) | Identify sources, enclose or remove, control pests alternatively, use fly screens |
| Carbon dioxide (CO2) | Indicator of indoor air polluted by humans, power losses | People, pets, combustion processes such as gas stoves or ethanol stoves | Ventilate more frequently, avoid ventilation systems and open flames |
| Fine dust | Irritation and irritation of the respiratory tract, headaches, suspected cancer | Combustion processes such as tobacco smoke, e-cigarettes, ethanol stoves, abrasion of textiles | Ventilate more frequently, ventilation systems with fine dust filters, avoid sources, good supply air filters in ventilation systems |
| Formaldehyde | Irritation of the conjunctiva and respiratory tract, headaches, suspected cancer in high concentrations | Tobacco smoke, chipboard and wood-based materials, paints, open flames (e.g. ethanol stoves, gas flames), disinfectants | Avoid smoking indoors, use low-formaldehyde glues for wood-based materials, remove sources of pollutants |
| Odorous substances | Annoyance, possible disturbance of well-being, stress factor | Paints, natural substances, drainpipes, leaky buildings, scented oils, people | Find out the cause of the odors and remediate, regular ventilation, ventilation systems |
| Carbon monoxide (CO), nitrogen oxides (NO, NOx) | Heart and vision problems, headaches, dizziness, central nervous dysfunction, internal suffocation | Leaking stoves and fireplaces, instantaneous water heaters without flues, gas stoves, garages | Have appliances checked regularly, replace old appliances, active ventilation to the outside |
| PAH* (polycyclic aromatic hydrocarbons) | Cancer, unpleasant odors | Parquet adhesives and damp-proofing containing tar, carbolineum | Seal or remove |
| PCB* (polychlorinated biphenyls) | Damage to the foetus, impairment of the immune system, suspected cancer | Grouts and sealants, small capacitors in fluorescent lamps, old wall paints | Identify and remove sources |
| Radon | Lung cancer | Soil, building materials | Carry out radon measurement, radon-proof construction, sealing, ventilation |
| Biogenic contaminants (molds and bacteria, viruses) | Allergies, irritation, unpleasant odors, infections | Damp building components and materials, germ formation in humidifiers, people | Tackling the cause: repairing structural damage, reducing humidity, ensuring good ventilation |
| Tobacco smoke and e-cigarettes | Cardiovascular and respiratory diseases, lung cancer, asthma | Cigarettes, cigars, pipes, e-cigarettes | Stop smoking indoors and in the car |
| VOC (volatile organic compounds) | Odor nuisance, irritation of the respiratory tract, impairment of the nervous system, mental disorders, partly carcinogenic | Solvents, paints, varnishes, adhesives, leveling compounds, pine wood, commercial operations, ethanol stoves (benzene) | Ventilate, use solvent-free products, remove or seal the source, use spruce instead of pine, renovate commercial operations |
Literature and regulations
[1] BMK: Position paper on the effects of energy-saving measures on indoor air. Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology (BMK), 2023.
[2] Leusden, P.; Freymark, F.: Representation of room comfort for simple practical use. In: Health Engineer 72, No. 16, 271 – 273, 1951.
[3] Allen, J.; MacNaughton, P.; Satish, U.; et al.: Associations of cognitive function scores with carbon dioxide, ventilation, and Volatile Organic Compound Exposures in office workers: a controlled exposure study of green and conventional office environments. Environ Health Perspect 124: 805 – 812, 2016.
[4] Strøm-Tejsen, P.; Zukowska, D.; Wargocki, P.; Wyon, D-P.: The effects of bedroom air quality on sleep and next day performance. Indoor Air Vol 26, Issue 5. 679 – 686, 2016.
[5] Pettenkofer, M. von: On air exchange in residential buildings. Cotta, Munich 1858.
[6] BMK: Guideline for the assessment of indoor air. Developed by the Indoor Air Working Group of the Austrian Federal Ministry for Climate Protection, Environment, Energy, Mobility, Innovation and Technology (BMK), loose-leaf collection, from 2003.
[7] OENORM H 6039: Ventilation systems – Controlled mechanical ventilation of school, class or group rooms and rooms with a similar purpose – Requirements, dimensioning, design, operation and maintenance, February 1, 2023.
[8] BMK: Position paper on ventilation requirements in educational institutions. Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology (BMK), 2023.
[9] Tappler, P.; Mu̱oz-Czerny, U.; Hutter, H-P.; et al.: Innenraumschadstoffe durch Verbrennungsprozesse РEthanol- und Speicher̦fen. Commissioned by the BMLFUW, self-published, 2015.
[10] OIB Guideline 3: Hygiene, Health and Environmental Protection, OIB-330.3-011/23 and Explanatory Notes thereto OIB-330.3-012/23, 2023.
[11] OIB Guideline 6: Energy Saving and Thermal Insulation. OIB-330.6-026/23, 2023.
[12] Interior website of the Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology (BMK), available at https:// www.bmk.gv.at/themen/klima_umwelt/luft/innen- raum.html, checked on February 12, 2024.
[13] BMNT: Leitfaden zur Vorbeugung, Erfassung und Sanierung von Schimmelbefall in Gebäuden (“Schimmelleitfaden”), prepared by the Arbeitskreis Innenraumluft (currently BMK), Vienna, 2019, available at http://www.innenraumanalytik.at/ schimmelleitfaden.pdf, checked on February 12, 2024.
[14] ISO 16000-41: Indoor air. Part 41: Assessment and classification. August 4, 2023.
