„Based on statistics, Europeans spend 8 hours a day at their workplace, 7 hours in their living rooms and 7 hours in their bedrooms."

Source: Kurt Henseler: With plants for healthy air in your room

We spend most of the day indoors that is why the air-quality is really important in the room we work or live in.
Wrong or improperly fixed ventilators, rare airing, pollutants evaporating from furniture-paints and leaks may cause headache, discomfort and tiredness.

Indoor air quality

There are several factors that influence how we feel about the air and the effect it has on us during a longer period of time: temperature of the air, relative humidity, amount and smell of flying dust.

Air consists of 78% nitrogen, 21% oxygen, and the 1% left is made up of several rare gases. When breathing, we inhale oxygen and exhale carbon-dioxide. Though we need air rich in oxygen, the average 21% can decrease to 16% without us noticing it, and a 3-4 times increase of the original much lower than 1% carbon-dioxide concentration can still be easily tolerated.

But we do feel the “smell” of the room which consists of the natural exhalation of the people inside, the odour of the furniture and carpets. In this case we might feel uncomfortable and find the air musty – a quick air-refreshment can help a lot! If it is cold outside airing should be short so that only the air in the rooms cool down and not the surface of the furniture. Thus, after airing we will need much less energy to reach the original temperature in the room.

If the air is too dry in the room, it can cause a number of problems as well.

At different temperatures, air can fix different amounts of water.

The amount of water vapour in the air at any given time is usually less than that required to saturate the air. The relative humidity is the percent of saturation humidity, generally calculated in relation to saturated vapour density.

Relative humidity=actual vapor density/saturation vapor density*100%

Most people perform best if the temperature is between 18-24 °C, at a 45-55 % relative humidity.

Too high humidity (which is quite rare) leads to mouldiness and can be responsible for respiratory problems.

Low humidity (below 30%) is very common especially in places with ventilation. During winter it is even worse, as heating increases dryness.

Dust keeps floating in dry air for a longer time, in addition stronger advection caused by intensive heating and ventilation do not let the dust particles settle down. Clothes might get static (e.g. when shaking hands we can shock each other).

If air is dryer than optimal, the mycoderm of the air-passages dries and can give way to respiratory illness. As a result, people working in such conditions easily catch cold, and their skin becomes too dry.

A few words on air-conditioning

Artificial ventilation is becoming a basic feature in newly-built offices – you can find it almost everywhere. Normally it should be the walls of a building that ensures proper insulation (keeping cool in summer and warm in winter). However, quite sadly, nowadays a lot of buildings are not planned and built ‘thermo-economically’.

Air-conditioning is "indispensable" in summer, but in a great number of cases the same system is used for heating in the winter. Well-adjusted and maintained conditioners do not cause problems, though in Hungarian climate conditions they are only needed in the summer months. Whenever it is possible, turn it off (e.g. autumn and spring-time) – this way you will consume much less energy! And if you want to get some fresh, simply open the window!

Before turning off the conditioning, it is useful to make clear what system the appliances work in – it is possible that we can only hope to save energy if more people turn off the heating/cooling at the same time (e.g. you can only turn off a cooling unit, if all the conditioners are switched off in the concerned rooms).

If set on too low degrees in the summer, ventilation can cause a lot of illness as people coming inside from the summer heat cool down too quickly. That is why we suggest not to set the temperature below 20-22 °C.

Improperly cleaned and maintained conditioners can spread certain illnesses as they blow out viruses they previously collected.

Too strong advection is not good for your face because it makes it dry.
There are, of course, alternative ecological solutions for conditioning new buildings, such as shutters and blinds with thermal sensors, dark glass, or trees planted at the southern side of the building. It is cheaper and healthier not to let in summer heat than using extra energy to compensate it.

Pollutants of indoor air

Toxins evaporating mostly from lacquers, glues and paints can reach quite high concentrations in indoor air. The pollutant mentioned most often is formaldehyde, but several other compounds can cause problems as well.
The following table lists the most common organic compounds in indoor air:
The following table lists the most common organic compounds in indoor air:[1]

Acetone Dimethyl-naphthalene
Benzene* Trichloretene
Toluol Dichloro-benzene*
Xylol Decyl alcohol
Styrene* Dimethylamine
Ethyl- benzene Trichlor-fluorine-methane
Ethyl-methyl-benzene Methylene chloride*
Trimethyl-benzene Chloroform
Tetrachloro-ethylene* Acetic acid
Naphthalene Formaldehyde*

Materials marked with* are carcinogenic.

Potential sources of these pollutants in the office can be glued synthetic floors; correctors, glues and instant glues containing solvents, so it is better to avoid the use of these. The table below provides more information on which toxins occur in often-used office products:


Name of toxin

To be found in


Ethanol Glues, markers Narcotizes
Methyl-acetate Glues Narcotizes
Ethyl-acetate Instant glues Narcotizes, may cause death if taken in big quantity, damages mycoderm
Acetone Glues Narcotizes in big quantity, may damage eyes and stomach-mycoderm
Benzene Can be found in toluol as a pollutant Narcotizes, carcinogenic
Toulol Instant glues, markers/highlighters Narcotizes, may cause spasm, probably carcinogenic
Xilol Instant glues, markers/highlighters Narcotizes
Methylene-chloryde Instant glues Narcotizes
1,1,1-Trichloretan Solvents of instant glues and correctors Narcotizes, may cause death if taken in big quantity
Trichlorethene Instant glues Narcotizes, damages brain, kidneys and liver

Positive effects of indoor plants

Indoors plants produce oxygen, evaporate water, and certain species are capable of cleaning office air of pollutants. Besides, they are good for uplifting workers’ mood which is quite an important aspect.

In case you would like to know on what level your office is in respect to plants, fill in the check list on the left, using the icons to read the questions!