THINGS YOU SHOULD KNOW ABOUT AIR POLLUTION AND AIR FILTRATION
Airborne particles have different sizes and are measured in μm (microns or micrometers). The size of particles is directly linked to their potential of causing health problems. Small particles less than 10 micrometers in diameter pose the greatest problems because they can get deep into your lungs, and some may even get into your bloodstream. PM or Particulate Matter is the sum of all solid and liquid particles suspended in air. They are distinguished according to particle size.
PM 10 (µg/m³) is the sum of inhalable particles, with diameters of 10 μm (microns or micrometers) and smaller.
Pm 2.5 (µg/m³) is the sum of inhaliable fine particles, with diameters of 2.5 μm (microns or micrometers) and smaller.
Pm 0.1 (µg/m³) is the sum of inhalable ultrafine particles, with diameters of 0.1 μm (microns or micrometers) and smaller.
The AQI is an index for reporting daily air pollution.To present the air quality situation in European cities in a comparable and easily understandable way, all detailed measurements are transformed into a single relative figure: the Common Air Quality Index (AQI or CAQI). They are based on 3 pollutants of major concern in Europe: PM10, NO2, O3 and will be able to take into account up to 3 additional pollutants (CO, PM2.5 and SO2) where data is also available.
The values are updated hourly (for those cities that supply hourly data) and the previous day’s indexes are also presented. The higher the AQI value, the greater the level of air pollution and the greater the health concern.
The HEPA filter (high efficiency particulate air / arresting) was invented by the USA Atomic Energy Commission during the Manhattan Project (World War II), which saw a need for a system to clean air contaminated with radioactive particles. They are made of randomly arranged fiberglass to form a mat. The mats are then arranged in pleats in order to maximize the amount of surface area. When air flows through the hepa filter, particles are trapped by the glass fibers and removed from the air. The particles remain trapped in the filter as the clean air continues out of the filter. It is till today the most proven and effective way to clean indoor air from airborne pollution and as such it is used in hospitals all around the world.
The lack of a worldwide uniformed HEPA filter classification and the constant simultaneous effort of institutions of different countries to find a solution to this matter makes it difficult for costumers and manufacturers to understand and apply those regulations. Let us try to explain to you this difficult subject, and the reason why we develop the filters the way we do in a understandable manner.
The United States introduced the US MIL-standard 282 to protect costumers of air purifier manufacturers which do not deliver HEPA filters in their products even if they claim to do so. They defined that an air filter can be named HEPA only if it can remove 99.97% or more of particles that are sized 0.3 microns and bigger. Dispersed oil particles (dop) is used to test the integrity of the HEPA filter.
The European Union introduced the EN 1822 standard which classifies HEPA filters in 3 categories; EPA (Efficiency Particulate Air) with a range of efficiency from 85 to 99.5% HEPA (High Efficiency Particulate Air) with a range of efficiency from 99.95 to 99.995% ULPA (Ultra Low Penetration Air) with a range of efficiency from 99.9995 to 99.999995%. They use the so called most penetrating particle size (mpps) which are particles with a size of 0.3 microns and smaller to test the integrity of the HEPA filter.
The different testing methods of the US and EU adds complications on this already complicated subject. If the same HEPA filter is testes by US MIL-STD 282 (dop 0.3 microns) it will have an efficiency of 99.97%, and if it is tested by the EN 1822 (mpps 0.3 microns ) it will have an efficiency of 99.5%. Depending on the testing method, the same filter will have a different efficiency percentage.
HEPA filter efficiency is tested with 0.3 microns because scientific tests have shown that this size of particle is the most difficult size to capture by a HEPA filter, which is explained by the four different methods of arresting particles in the fiberglass (staining, inertial, interception and diffusion). What is important to know is that not only larger particles then 0.3 microns are easier to capture, but opposed to a logical approach, it is also true that smaller particles then 0.3 microns are easier to capture by the hepa filter. This is very important because 90 % of the air born particles are smaller then 0.1 microns. VAURON for its multi-layer HEPA filters uses HEPA with class H13. This density of HEPA filter and the Air delivery Rate of 500m3/h guaranties that even with less Air Changes you will have clean air in shorter time interval.
The combination of pre-filter, HEPA filter and active carbon filter is an approved way of constructing a multi-layer filter for purifying the air.
The combination of pre filter, HEPA filter and activated carbon filter is proven to be the most efficient way to construct multi-layer filters for air purifiers.
Ionizers are devices which use high voltage to ionise (electrically charge) air molecules. Airborne particles are attracted to the electrically charged particles (ions) in an effect similar to static electricity. These ions are de-ionised by seeking earthed conductors, such as walls, ceilings and furniture. Air born pollutants are not permanently removed from the indoor space, as it is with a hepa based purification, they only lose their ability to fly free in the air of indoor spaces. The black wall effect is a common visual manifestation of the above described process and the proof that this air filtration system has a limited range, thus cannot manage to purify the entire air of a standard size room.
“There is also the concern that the joined particles may simply find a suitable surface on which to land within your own respiratory system, clinging to and building up on your air passage walls.”
Ionizers produce ozone. Most of them stay below the amounts allowed by the epa (us environmental protection agencyand) and can „name” their products ozonefree, which in fact is not the case. “even the best ionisers will also produce a small amount of ozone—triatomic oxygen, o3—which is unwanted.”
“The bottom line is that these products don’t work anyway, so why would anyone want to expose themselves to a level of ozone which, when added to the ozone that is already in the home, certainly isn’t going to do them any good?”
To combine HEPA filtration systems with an ionizer is against the logic of HEPA based purification. Well constructed HEPA air purifiers need to have a powerful air delivery rate to maximize the circulation of the air in the room, and as such maximize the particle volume that passes trough the HEPA filter so they can be permanently arrested. If the ability of the particles to fly has been reduced with the process of ionization, then it is harder for any purifier to suck them into the HEPA filter because they are glued to various surfaces in the room that needs to be purified.
Due to the below-average performances and potential health risk VAURON does not build air purifiers with build in ionizers of any kind.
Please read the following statements published by various established organizations on the subject of air purification with Ozone Generators
„Ozone is a potent lung irritant and exposure to elevated levels is a contributor to the exacerbation of lung disease; it is especially dangerous for persons with asthma and other chronic lung diseases, children and the elderly.„
source: American lung association (www.Lungusa.Org)
„How is ozone harmful? When inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections. Manufacturers and vendors of ozone devices often use misleading terms to describe ozone. Terms such as “Energized oxygen” or “Pure air” suggest that ozone is a healthy kind of oxygen. Ozone is a toxic gas with vastly different chemical and toxicological properties from oxygen. Several federal agencies have established health standards or recommendations to limit human exposure to ozone.„
source: US Environmental Protection Agency (www.Epa.Gov)
„The California Air Resources Board on Thursday banned popular in-home ozone air purifiers, saying studies have found that they can worsen conditions such as asthma that marketers claim they help to prevent.„
Water-based air purifiers filter only a very small group of air born particulates ( insoluble particulates ). The efficiency of water-based air purification stands in no comparison to the efficiency of a HEPA / activated carbon air purification. Another issue with water is that it has the potential to introduce pollution into your environment because water is a key ingredient in mold growth. It could grow in the air purifier itself or in your room because the water-based air purifier contributes to higher levels of humidity.
The efficiency of an air purifier is mainly a result of its Air Delivery Rate (ADR), its HEPA Filter and the calculated Air Changes Per Hour (ACH)
The Air Delivery Rate (ADR) is the volume of air that passes trough the air purifier in one hour (m3/h).
– Higher ADR = more air will pass trough the air purifier in one hour
– Lower ADR = less air will pass trough the air purifier in one hour
Every HEPA filter has a grade / density (for example class H13) and a specific surface area (size).
– If the HEPA filter is of lower class, more air can pass through the filter, but at the same time less particulate matter will be arrested.
– If the HEPA filter is of higher class, less air can pass through the filter, but at the same time more particulate matter will be arrested.
– If the HEPA filter surface area is smaller, less air can pass through the filter.
– If the HEPA filter surface area is bigger, more air can pass through the filter.
The Air Changes per Hour (ACH) gives information on how many times an air purifier filters the air in a given room in one hour. It is one of the most important and at the same time, one of the most misleading information for any potential costumer. There is no global or local regulation on how many air changes per hour are needed to ensure an efficient air purification of indoor spaces. This is why manufacturers use from 2 up to 6 ACH to calculate the maximum room coverage of their purifiers. Please see the simple mathematical approach below for a better understanding of the importance of the ACH and its close relation to the suggested room size of an air purifier.
EXAMPLE 1: AIR PURIFIER with an ADR of 150 m3/h
2 ACH = 150 m3/h / 2 (ACH) = 75 m3 / 2.5 (room height) = 30 m2 (suggested room size)
4 ACH = 150 m3/h / 4 (ACH) = 37.5 m3 / 2.5 (room height) = 15 m2 (suggested room size)
6 ACH = 150 m3/h / 6 (ACH) = 25 m3 / 2.5 (room height) = 10 m2 (suggested room size)
EXAMPLE 2: AIR PURIFIER with an ADR of 300 m3/h
2 ACH = 300 m3/h / 2 (ACH) = 150 m3 / 2.5 (room height) = 75 m2 (suggested room size)
4 ACH = 300 m3/h / 4 (ACH) = 75 m3 / 2.5 (room height) = 30 m2 (suggested room size)
6 ACH = 300 m3/h / 6 (ACH) = 50 m3 / 2.5 (room height) = 20 m2 (suggested room size)
EXAMPLE 3: AIR PURIFIER with an ADR of 450 m3/h
2 ACH = 450 m3/h / 2 (ACH ) = 225 m3 / 2.5 (room height) = 90 m2 (suggested room size)
4 ACH = 450 m3/h / 4 (ACH) = 112.5 m3 / 2.5 (room hight) = 45 m2 (suggested room size)
6 ACH = 450 m3/h / 6 (ACH) = 75 m3 / 2.5 (room hight) = 30 m2 (suggested room size)
By using 2 ACH a manufacturer of an air purifier with a ADR of 150 m3/h can suggest that his purifier is sutable for a 30 m2 room.
By using 4 ACH a manufacturer of an air purifier with a ADR of 300 m3/h can suggest that his purifier is sutable for a 30 m2 room.
By using 6 ACH a manufacturer of an air purifier with a ADR of 450 m3/h can suggest that his purifier is sutable for a 30 m2 room.
As shown above, a costumer cannot always relay on the room sizes suggested by the manufacturers of the air purifiers and that they need to do their own math.
If your room size is 30 m2 and your room height is 2.5 m, then your room (or air) volume is 75 m3. if you want 4 Air Changes per Hour (ACH), then you need a purifier that has at least an Air Delivery Rate (ADR) of 300 m3/h (30 m2 x 2.5 m = 75 m3 x 4 ach= 300 m3/h)
The ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) suggest 4 ACH for patient rooms and 6 ACH for intensive care units in hospitals. Therefore, we calculate the suggested room size of our purifiers using 4 ACH in our mathematical equation.
Please have in mind that an air purifier with an ADR of 300 m3/h will have to be operated in the highest, and as such loudest, fan speed to achieve proper purification in a 30 m2 room. Due to the airflow design of most air purifier on the market, the sound pollution on the highest fan speed is not suitable for a long term use. We recommend purchasing an air purifier which has a greater ADR value then mathematically needed, and the ability to achieve the AIR CHANGE RATE of 4 times in one hour on a lower fan speed.
Indoor air pollution varies drastically in close relation to indoor activities and outdoor environmental conditions. This means that the question: “ how many purifiers do i need for my 90 m2 apartment “ often asked by concerned customers cannot be answered based on a simple mathematical calculation. The answer is always based on an individual trial and error approach which in time will show how many unites are needed to ensure efficient purification with low noise operation during the average air pollution periods, and efficient purification of the indoor air in periods of high indoor air pollution by using the high fan speed setting. Based on our experience, we can honestly say that you can never have too many air purifiers in your indoor space when it comes to purification the indoor air in highly polluted areas of the world.
The knowledge of the actual PM1, PM2.5 and PM10 count helps customers to apply the air quality guidelines and recommendations of the WHO ( World Health Organization) which are based on the PM 2.5 and PM 10 amounts in the air. The-real time PM 2.5 feedback of an air purifier furthermore confronts everybody with the inevitable air “quality” issue in our indoor spaces, helping everybody acknowledge that even though we cannot see, smell or taste the pollution in the air, it is in fact all around us in great quantity.
VAURON Air Purifiers have build in real-time laser-based PM 2.5 sensors and the values are displayed on the LCD screen on top of the purifier allowing you to decide for yourself what values of PM 2.5 is suitable for you.