MEASURED VALUES

With the exhaled air, every person spreads a number of gases and also aerosol particles in their immediate surroundings. When speaking, shouting, singing, but especially when coughing, sneezing or exercising, more particles are emitted. If there are pathogens such as SARS-CoV-2 viruses or flu viruses in the airways, aerosols can contain these pathogens. The ProxiCube^® measures the number of liquid, respirable aerosols (liquid fine dust less than or equal to 2.5 micrometers (PM_2.5). The value is given in the number of drops / cm³ and is shown in parallel on the ProxiCube’s display^® NX3 is displayed.

Carbon dioxide (CO₂) is one of the natural components of the air and is an important greenhouse gas in the earth’s atmosphere. Excessive carbon dioxide concentrations in the interior lead to reduced performance and fatigue. The Federal Environment Agency recommends letting fresh air into the room from outside if a value of 1,000 ppm CO₂ is exceeded. Symptoms such as poor concentration or headaches appear long before the indoor air is consciously perceived as bad.

Our defined evaluation of the values for the presentation in the app, on the ProxiCube^® display and via the traffic light:

1. green icon for values from 0 to 1,000 ppm
2. yellow icon for values from 1.001 to 1.500 ppm
3. red icon for values from 1,501 ppm

 

Air pollutants are briefly referred to as VOCs. The abbreviation VOC stands for volatile organic compounds. These are organic-chemical compounds in the boiling range of approx. 50–260 °C. VOCs are contained in room air practically anytime and anywhere.

An increased concentration of TVOC can initially manifest itself in a changed smell and taste perception or irritation of the eyes or mucous membranes. Other effects are poor concentration, exhaustion, dry skin or headaches.

The guide values for the occurrence of TVOC comprise five levels:

1. ≤ 0.3 mg / m³ – hygienically harmless.
2. > 0.3–1 mg / m³ – Hygienically harmless as long as no guideline values are exceeded for individual substances or groups of substances.
3. > 1–3 mg / m³ – Hygienically noticeable.
   Use of rooms that are used regularly is only acceptable for a limited period (<12 months).
4. > 3–10 mg / m³ – Hygienically questionable.
   Use of rooms that are used regularly is only acceptable for a limited period (<1 month).
5. > 10 mg / m³ – Hygienically unacceptable.
   Avoid using space if possible. A stay is only permitted for an hourly / limited period per day.

Indoor air quality (IAQ)
Under the term indoor air quality or indoor air quality, those aspects of indoor air are considered that have an impact on people’s wellbeing and health. People in Europe spend an average of 90% of their life indoors today. Each person breathes in 12,000 liters of air per day, depending on their age and activity. This is far more than what a person ingests through food (food and drinking water). Against this background, it becomes clear how important the quality of indoor air is for people’s wellbeing.

The IAQ scale ranges from 0 (clean air) to 500 (heavily polluted air). During operation, the algorithms are automatically calibrated and adapt to the typical environments in which the sensor is operated (e.g. at home, at work, in the car, etc.). This automatic background calibration ensures that users experience consistent IAQ performance.

1. With values from 0–100> IAQ house green
2. With values from 101–150> IAQ house yellow
3. With values from 151–200> IAQ house orange
4. With values from 201–500> IAQ house red

 

Fine dust dry, respirable

The ProxiCube^® measures the number of dry, respirable particles (dry fine dust ≤ PM_2.5) with the applied measuring method. Fine dust is the term used for particles with an aerodynamic diameter of less than 2.5 micrometers (µm). The fine particles can penetrate deeper into the airways, stay there longer and cause lasting damage to the lungs. In contrast to other pollutants, there are no real limit values for the concentration of fine dust below which no health effects are to be expected – even the smallest amount is considered harmful. Specification of the values in µg/m³

Fine dust, respirable (PM_1.0 PM_2.5)

The ProxiCube^® measures fine dust in the air of sizes ⁠PM_1.0 and PM_2.5. Fine dust with an aerodynamic diameter of less than or equal to 1.0 micrometers (PM_1.0) or less than or equal to 2.5 micrometers (PM_2.5) is a health risk, primarily due to its small size. The fine particles can penetrate deeper into the airways, stay there longer and cause lasting damage to the lungs.

Limits:
Federal Environment Agency annual limit value = PM_2.5 25 µg/m³

For the smaller particles PM_2.5 there are only non-binding target values of 25 µg/m³ of the EU and WHO. For even smaller particles – although much more dangerous – there are currently no limit values. Specification of the values in µg/m³

Fine dust, not respirable (PM_4.0 PM₁₀)

The ProxiCube^® measures fine dust of sizes ⁠PM_4.0 and PM₁₀⁠. Particles with an aerodynamic diameter of less than 10 micrometers (µm) are called fine dust. Most of the fine dust emissions come from combustion processes (motor vehicle traffic, building heating and the like) and production processes. To a lesser extent, fugitive emissions from trade and industry, agriculture, fireworks, cigarettes and barbecues are responsible for dust emissions.

Limits:
Federal Environment Agency daily limit value = PM₁₀ 50 µg/m³
Federal Environment Agency annual limit value = PM₁₀ 40 µg/m³

The Federal Environment Agency specifies a daily limit value of 50 µg/m³ for fine dust particles PM₁₀, which may only be exceeded on 35 days a year. In general, a maximum annual mean value of 40 µg/m³ applies. Specification of the values in µg/m³

The air temperature has a significant influence on the reaction time of chemical processes and thus on the human metabolic process. Temperatures that are too high or too low can have a negative impact on mental or physical health.

The Federal Environment Agency recommends specific guide values for the room temperature. A distinction is made between the respective uses of the rooms.

We recommend 21–23 °C in living areas. The guide value for children’s and bathrooms is 23 °C, in the kitchen 18–19 °C and in the bedroom 16–18 °C. A room temperature between 21–22° C is recommended for offices.

The compression, i.e. the compression of the air, is referred to as air pressure. Changes in air pressure are caused by various complex atmospheric processes.

Researchers assume that air pressure fluctuations with an amplitude (oscillation) between 0.3 and 0.5 hPa (hectoPascal) have an impact on blood pressure, circulation and concentration.

If the value falls below 0.73 hPa, the type and duration of the activity must be adjusted for health reasons.

Air humidity describes the proportion of water vapor in the gas mixture in the air. Relative humidity describes the ratio of the water vapor actually contained in the air to the maximum possible water vapor content.

If the humidity in a room is too low, the breathing capacity is reduced. In addition, dryness can lead to skin irritation and irritation. The mucous membranes can also dry out. Excessive relative humidity can cause discomfort and stress on the circulatory system, as well as impaired productivity. Probably the greatest danger in rooms with too high humidity is the formation of mold. A relative humidity between 40 % and 50 % is recommended in closed rooms.

The dew point is the temperature below which water vapor in the air condenses to form water. At this temperature point the air is completely saturated with water. If the dew point is too high or too low, water can condense, which can lead to mold.

Recommendations for the relative humidity also result in direct recommendations for the dew point. At room temperature, the recommended lower limit of the dew point is approx. 9 °C – below this the air would be perceived as too dry. The upper limit of the dew point is approx. 15 °C – above this the air would be perceived as too humid.