Healthy Indoor Air: The Often Underestimated Foundation for a Healthy Life
Healthy nutrition and exercise are central components of a good lifestyle – yet the air we breathe is often overlooked. Polluted air is one of the greatest health hazards, especially indoors. With modern air purifiers, we can actively ensure better indoor air and thus improve our well-being.
Much thought is generally given to healthy foods, good drinking water and sufficient exercise for a healthy lifestyle. The air we breathe receives significantly less attention when it comes to "living healthier". Air purifiers are still "exotic" in German households. According to estimates by the World Health Organization (WHO), about eight million people died in 2012 from diseases related to polluted air. Poor air quality is "the greatest environmental health risk. The most common causes of death are strokes and coronary heart diseases, followed by chronic lung diseases and cancer," explained Maria Neira, Director of the WHO Department of Public Health and Environment. According to WHO, 3.7 million deaths are attributed to poor outdoor air and about 4.3 million deaths to indoor air. Outdoor air is beyond personal control, but indoors, air purifiers are an effective measure for healthy indoor air.
The air pollutants nitrogen dioxide, fine dust and ozone also endangered the health of people in Germany in 2014. This is confirmed by preliminary evaluations from the Federal Environment Agency. Nitrogen dioxide, which mainly comes from vehicle exhaust emissions, is becoming pollutant number one. "Despite low fine dust levels, the health risk remains. Because there is no threshold for fine dust – health damage occurs even at low fine dust concentrations. This has been repeatedly confirmed by the World Health Organization (WHO)," states UBA President Maria Krautzberger.
The World Health Organization has published two fundamental texts, Selected Pollutants and Dampness & Mold, on indoor pollutants (WHO Guidelines for Indoor Air Quality). These WHO guidelines for protecting public health introduce a range of chemicals commonly found in indoor air. The substances covered—benzene, carbon monoxide, formaldehyde, naphthalene, nitrogen dioxide, polycyclic aromatic hydrocarbons (especially benzo[a]pyrene), radon, trichloroethylene and tetrachloroethylene—are frequently present at health-concerning concentrations according to WHO. The sources of exposure themselves are found indoors. The ad-hoc working group on indoor air guideline values of the Indoor Air Commission (Federal Environment Agency) and the Supreme State Health Authorities quantitatively assess indoor air pollution and set nationwide uniform guideline values. Meanwhile, the term "healthy indoor air" has become established.
"Healthy indoor air" refers to air that is free from pollutants or where pollutants are so low according to guidelines and threshold values that no health risk exists. Pollutant loads arise from the building materials of the building or room, furnishings such as floors, carpets and furniture, from devices, from humans themselves who emit organic substances and odours, and allergens such as house dust mite droppings, fungal spores, animal hair and pollen. Therefore, indoor air must be regularly renewed. A rule of thumb is that about 36 cubic metres of air per hour must be exchanged with outdoor air for each person. Ideally, this exchange is with outdoor air free from dust, soot, pollen or fine dust, which is, however, unrealistic. Without technical aids such as an air purifier, healthy indoor air is hardly achievable. Modern air purifiers are powerful and highly efficient at filtering out pollutants contained in the air.
Where Air Purifiers Provide Relief
Air filters for allergy sufferers
Allergens and pollen suspended in the air are so tiny that they are invisible to the human eye. The effect on the body is all the more severe for allergy sufferers. Good air filters should feature a high-quality HEPA fine dust filter. A HEPA fine dust filter consists of packed glass fibres, can be folded multiple times, and can remove contaminants down to 0.3 micrometres by 99.97 percent. An air filter equipped with a corresponding HEPA fine dust filter leads to a noticeable relief of allergic symptoms.
Air filters for asthma sufferers
Up to 75,000 dust particles are inhaled from unfiltered air. Increasingly due to high air pollution, the number of asthma cases rises by 50 percent every 10 years. Air filters for asthma sufferers should filter out almost completely the most common triggers of asthma attacks from the air, such as dust, chemicals or pollen, as well as other irritating and lung-penetrating pollutants. The air filter should have a separation efficiency of more than 99.75 percent (at least filter class H13 or H14). To also filter out volatile substances and various chemicals, an activated carbon filter should be installed in the air filter.
When choosing an air filter, asthma sufferers should pay particular attention to the air circulation rate in addition to the filtration methods and filter quality. Air filters with very high filtration properties can be less effective due to the associated lower air circulation rate. Conversely, an air filter with a high circulation rate but less effective filters can also be less effective. Therefore, special attention should be paid to the room air volume (length x width x height of the room in metres). For asthma sufferers, an air filter that can filter the entire room air volume at least twice per hour is recommended.
Air filters in smoker households and smoking rooms
In rooms where smoking takes place, air filters should actually be standard. The health risks of smoking as well as the no less serious dangers of passive smoking are well known. Tobacco smoke consists of around 4,000 substances, of which 20 are classified as carcinogenic, i.e. cancer-causing. The harmful substances penetrate deeper into the alveoli than conventional dust particles and multiply the risk of respiratory diseases, cardiovascular diseases and lung cancer. A single cigarette produces about two litres of smoke in enclosed rooms. Passive smoke consists of sidestream smoke and exhaled mainstream smoke. About 55 percent of the tobacco in a cigarette burns as sidestream smoke. For air filters to effectively filter out the smoke, in addition to a high-quality HEPA filter, an activated carbon filtration stage should also be installed. Especially if children live in a smoker household, an air filter can greatly reduce the dangers of tobacco smoke. Carbon monoxide, gases and nicotine irritate not only the respiratory tract but also the eyes. Accompanying symptoms such as fatigue, concentration weakness and malaise are also attributed to smoke. Besides the health aspect, air filters in smoking rooms also contribute to well-being.
Air filters for the average consumer
The right to access clean water was recognised as a human right by the United Nations General Assembly on 28 July 2010. The right to healthy air, however, is not even remotely on any agenda, although growing air pollution costs millions of lives annually. The places of use for air filters are no longer limited to particularly polluted rooms. Air filters are no longer just a health care aspect for only health-compromised and respiratory-sensitive persons. Exposure to substances from building materials, furnishings and everyday objects indoors is diverse. Added to this is general outdoor air pollution. It is actually surprising that an air filter is not already a household everyday item like computers, coffee machines, washing machines, microwaves or ovens.
Areas of effectiveness of air filters
Air filters against odours
Food smells, human odours, pet smells, musty-smelling, poorly ventilated rooms, smells from strong cleaners or furniture are just some of the many everyday odours. Odours are the result of chemical reactions. At the source of the odour, bacteria develop that release molecules which are transported by positive ions in the room air. To eliminate odours, an air filter must be equipped with ionisers that generate negative oxygen ions (anions). The amount of negative ions an air filter produces per hour is crucial.
Air filters against house dust (house dust mites)
Especially on summer days, it is often easy to see how many fine dust particles swirl through the air. House dust is not the only problem – the faeces of house dust mites are the actual burden. The 0.1–0.5 mm sized arachnids are harmless, but their faeces break down into dust and irritate the respiratory tract – especially in allergy sufferers. An air filter helps particularly after vacuuming, shaking out beds or beating furniture.
In winter, many mites die, break down into dust and worsen the situation due to dry heating air. An air filter can noticeably reduce the burden even in this season.
Air filters against mould
According to the Federal Environment Agency, mould spores can pose health risks – especially with allergies or asthma. Typical rooms for mould are kitchens, bathrooms and poorly ventilated rooms. Temperature differences and poor insulation promote mould growth. An air filter with HEPA fine dust filter as well as activated carbon against musty odours and ionisers for air disinfection helps preventively.
Air filters against ammonia
According to the Federal Environment Agency, around 95% of released ammonia comes from agriculture. It causes an unpleasant odour and health-hazardous fine dust. Air filters with ionisers, HEPA filter, activated carbon and photocatalyst are particularly suitable for reducing ammonia.
Air filters against fine dust
The legal daily limit value for PM10 is 50 μg/m³. The WHO even recommends a maximum of 20 μg/m³ as an annual average – a value exceeded in many regions of Germany. Especially PM2.5 fine dust (≤ 2.5 μm) is hazardous to health as it can penetrate deep into the lungs and enter the bloodstream.
HEPA filters capture particles from 0.3 μm at 99.97% – smaller particles are bound by ionisers (cluster formation) and thus filtered more effectively.
Air filters against plasticisers and chemical substances
Plasticisers such as DEHP are still widespread and pose health concerns. Sources include PVC floors, furniture, electrical cables, shower curtains etc. The substances are low volatile – ideal are air filters with ioniser, activated carbon filter and photocatalyst.
Air filters against viruses, bacteria and microorganisms
HEPA filters retain most bacteria and microorganisms, but not viruses. For viruses, UV-irradiated photocatalysts with titanium dioxide are needed, which generate OH radicals. These oxidise organic material (e.g. virus components) into H₂O and CO₂. For medical rooms, an air filter should combine all the mentioned technologies.
Filtration methods of air filters
HEPA Filter
HEPA filters are the most widely used filtration method in air purifiers. HEPA filters consist of packed glass fibres and are sometimes folded multiple times to increase filtration efficiency. HEPA stands for "High Efficiency Particulate Absorbing Filter" and good HEPA filters achieve an adsorption rate of up to 99.995 percent for the finest particles down to 0.3 micrometres in size. They filter out pollen, mould fungi, mould spores, dust, pet dander, mite faeces, bacteria, clothing fibres and fibre fragments. HEPA filters are classified into categories ranging from E10 (separation efficiency of 80 percent) to H14 (separation efficiency of 99.995 percent).
Ionisers and Ion Generators
Nature produces increased amounts of negative ions especially in coastal areas, forests, near waterfalls or after thunderstorms. Many people perceive this air as particularly fresh and pleasant. In an air purifier with ionisers, the technology serves several purposes. It enhances well-being, as high concentrations of negative ions have a positive natural effect on humans. They stimulate the cardiovascular system and have a relaxing effect on the nerves. Additionally, dust in all forms is electrostatically charged and binds even the smallest particles of 0.01 microns into larger dust particles (clusters). This increases filtration efficiency and allows even hard-to-filter fine particles (PM 2.5) to be better removed. The radicals generated during ionisation also partially eliminate pollutants such as components of cigarette smoke, solvents and many other volatile chemicals in indoor air. Viruses and bacteria are also killed by an air purifier with an ioniser.
Activated Carbon Filters
Activated carbon is a porous, fine-grained carbon with a large internal surface area that acts as an adsorbent. It is made from peat, wood, lignite, hard coal or nutshells. The carbon content is usually over 90 percent. Like a sponge, the pores are interconnected (open-pored). The internal surface area ranges between 300 and 2000 m²/g of carbon. The pores of activated carbon are classified into three categories: macropores with radii larger than 25 nm, mesopores with radii of 1-25 nm, and micropores with radii smaller than 1 nm.
Activated carbon is usually installed in thick mats in air purifiers and is mainly used to remove volatile air pollutants such as various emissions from building materials and furniture, plastics, cleaning agents and paints. Activated carbon in air purifiers also adsorbs gases and vapours from solvents, ozone and chlorinated hydrocarbons very effectively. A variety of viruses and bacteria are also trapped by activated carbon, as well as pollen, mould spores and dust particles. Since activated carbon is very fine-pored and clogs quickly, an air purifier should have a pre-filter, preferably a good HEPA filter, before the activated carbon.
Photocatalyst Filters
Through the photocatalytic effect, where titanium dioxide is produced by the photocatalyst and irradiated with UV light, hydroxyl radicals (OH radicals) are generated. These are highly reactive and break down organic material. What remains is usually stable organic material, especially CO2 and H2O. Air purifiers with a photocatalyst neutralise viruses, bacteria and other pathogenic microorganisms very effectively.
UV Light
UV light is frequently used in water treatment for disinfection. It is also excellently suited for disinfecting air in air purifiers. Ultraviolet radiation is a natural component of sunlight and has a high energy value. High UV exposure damages and destroys cells, genetic material and other organic substances. Therefore, UV filters in air purifiers are used to kill viruses and bacteria. UV light can also be used in air purifiers to produce ozone. Besides many viruses and bacteria, ozone destroys many chemical substances in indoor air.
For effective disinfection, some air purifiers use UV light with a wavelength of 253.7 nm. This wavelength belongs to the UV-C spectrum of ultraviolet radiation and has a particularly strong germicidal effect. Mercury vapour lamps are often used in air purifiers. The drawn-in room air is passed past the lamps and even a brief moment in the UV light area is enough to exert its germicidal effect. The effect of UV-C light is based on its destructive impact on the nuclei and enzymes of bacteria. In viruses, irradiation mainly causes damage to the RNA (ribonucleic acid). The lamps are installed in the air purifiers so that no radiation escapes outside, and the mercury vapour lamps do not release mercury.
Pollutant Register E-PRTR
E-PRTR (European Pollutant Release and Transfer Register) is the European pollutant release and transfer register. Anyone can check which air pollution occurs in their own region. The answers to these public questions are provided by open data from authorities, companies and other institutions. Open data are data and information that anyone can freely and unrestrictedly use and process further. The data are freely and freely accessible. Sensitive people, people with respiratory diseases or people who are sensitive to chemical substances can now get an overview via thru.de of which pollutants are released where and in what concentrations.
Causers and air pollutants according to E-PRTR:
Industrial air pollutants
- Nitrogen oxides (NOx)
- Sulfur dioxide (SO2)
- Particulate matter (PM10), smaller than 10 µm
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
Non-industrial heating systems
- Nitrogen oxides (NOx)
- Sulfur dioxide (SO2)
- Particulate matter (PM10), smaller than 10 µm
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
Road traffic
- Nitrogen oxides (NOx)
- Sulfur dioxide (SO2)
- Particulate matter (PM10), smaller than 10 µm
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
Shipping (national)
- Nitrogen oxides (NOx)
- Sulfur dioxide (SO2)
- Particulate matter (PM10), smaller than 10 µm
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
Air traffic (national)
- Nitrogen oxides (NOx)
- Sulfur dioxide (SO2)
- Particulate matter (PM10), smaller than 10 µm
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
Shipping (international)
- Nitrogen oxides (NOx)
- Sulfur dioxide (SO2)
- Particulate matter (PM10), smaller than 10 µm
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
Agriculture
– Particulate matter (PM10), smaller than 10 µm
– Ammonia (NH3)