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Why is indoor air more dangerous than the outdoor air?

time:2016-01-26 16:04from:Airbus Author:sea hits:

Most buildings constructed during the last 60 years have integrated complete ventilation systems (mechanical supply & exhaust air). It has been necessary because of the size of buildings and due to tighter and better insulated construction materials. All such buildings function like large vacuum cleaners whereby we spend most of our time in the filter bag i.e. indoors an absurd situation but unfortunately the truth. The indoor climate also creates a friendly environment for bacteria, fungus and virus to grow in.


The indoor air quality is in general proven to be 4-5 times worse than the outdoor air because most ventilation  can not handle the large amount of fine particles and the systems are often also malfunctioning as a result of:


  •   complete isolation (especially in countries with changing climate), which decrease the natural ventilation. 
  •   ventilation ductwork systems have been found to be dangerously dirty inside preventing airflow and balance. 
  •   only a fraction of the air particles get stuck in the supply air filter system, the rest pass on straight into the building. 
  •   the exhaust system is unable to efficiently handle the extraction of particles partially because they have a certain weight.
  •   bad situated supply air, for example too close to car exhaust fumes, restaurant exhaust, industry exhaust. 
  •   exhaust air is situated to close to the supply air, which means that the air the just went out comes back in again. 
  •   temporary turn-off of the ventilation system during the night (to save money) expose the filters and the ventilation systems to evaporation, which creates a living friendly environment for             fungus, bacteria, virus, and mould. These microbes are in the morning pushed into the building when the ventilation system is turned on. 
  •   the supply filter is changed too seldom, which results in the filter becoming a living environment for microbes that are constantly pushed into the building. 
  •   mechanical exhaust have been shown to cause pressure, which makes polluted air to be sucked into natural chinks and holes in the isolation and ground. 
  •   there are regulations and standards almost everywhere for minimum fresh air supply, these standards are however in general never met.