Healthy Buildings — Healthier People
Respiratory infections cause massive productivity losses and high health costs, to the detriment of companies and society. Influenza infections alone cause over 500 million cases of illness worldwide every year. Particular dangers emanate from buildings where many people packed in together closely,
or they already have previous illnesses.
 |
Office/ workplace |
School/ daycare |
Hospital/ retirement home |
13.000 litres
Air |
to 9 %
less productivity |
3 %
better grades |
10 %
of infections |
| Up to 13,000 litres of air flow through our nose, mouth and lungs every day. Air is food |
Poor indoor air quality can cause a production loss of 6–9% (1) |
Better air quality in schools increases the rate of students who pass a test by around 3% (3) |
Hospital-acquired infections affect around 10% of hospitalised patients worldwide 5) |
90 %
by viruses |
16 %
of lost working days |
2 x
as many days absent |
Up to 30 %
Air transmission |
| Approx. 90% of all acute respiratory infections are caused by viruses, mostly rhinoviruses (30–50%), influenza, parainfluenza and coronaviruses |
16% of lost working days for office workers result from respiratory illnesses (2) |
In daycare centres with controlled humidity, 3% of attendance days are lost due to cold symptoms compared to 5.7% with uncontrolled humidity (4) |
15% to 30% of infectious microbes in hospitals can be transmitted by air |
(1) Wyon, DP. “The Effects of Indoor Air, Quality on Performance and Productivity.” IndoorAir, U.S. National Library of Medicine, 2004
(2) Statista Research Department, Germany, 2020
(3) Haverinen Shaughnessy et al., Association between substandard classroom ventilation rates and students’ academic achievement, 2011
(4) Ritzel, G. Sozialmedizinische Erhebungen zur Pathogenese und Prophylaxe von Erkältungskrankheiten, 1966
(5) Report on the burden of endemic health care associated infection worldwide, World Health Organization, 2011
Mucous Membranes Protect Us
Humans are not defenceless against attacks by viruses and bacteria. Whether we become ill and how quickly we recover is determined by how well our immune system is working. In the respiratory tract, the mucous membranes protect us from infections through their self-cleaning function.
The mucous membranes have fine cilia on their surface that move freely in a thin fluid secretion (sol layer). On top of this is a sticky gel layer to which most of the inhaled viruses, bacteria and air pollutants adhere. As long as the cilia are free to move, they transport the mucus together with the microorganisms towards the larynx,
where it can be swallowed or coughed up.
Compromised Immune System
However, as humidity decreases, the removal of pathogens becomes less effective. At low humidity, water is extracted from the sol layer. The cilia are pushed further down and lose their mobility. The rising viscosity of the mucous membranes leads to a blockage of the mucus flow, thus increasing risk of infection by viruses penetrating the mucous membrane cells. If the relative humidity drops to 20%, the self-cleaning process comes to a complete standstill. Studies show that the highest transport speed and thus the lowest risk of infection is achieved at 45% relative humidity.
Making Buildings Healthier
The “Making Buildings Healthier” brochure is a
current summary of the most important
findings from medicine and
building technology.
Length 16 pages
Format DINA4
