Slide 1: Healthy Indoor Environment: Requirements for building technology
air Healthy Indoor Environment surfaces Requirements for building technology water view of a Doc w.hugi@bluewin.ch MD Walter Hugentobler Physician Medical Advisor, Condair AG
Slide 2: Resumé Dr. Walter Hugentobler
Resumé Dr. Walter Hugentobler Medical studies at the University of Zurich 1978-1985 Doctorate, specialist education in general internal medicine 1985-2012 Owner of a general medical practice 1995-2018 Lecturer at the Institute of Family Medicine, University of Zürich Academic and medical a
Slide 3: Humans' time spent outdoors versus indoors
350’000 years humans lived and 2000 years, humans lived in buildings, 200 years, working in factories and worked 100% outdoors still spending 100% of lifetime outdoors offices, living 90% indoors Industrial revolution air tight barrier filter ventilator air-conditioning Last 20 years, live and work
Slide 4: Lifestyle, building design and technology increasingly isolated humans from nature
Lifestyle, building design & technology increasingly isolated humans from nature air tight barrier filter ventilator air-conditioning in the last 200 years
Slide 5: Microbes have escorted and influenced the evolution of humans
2,5 billion years microbes, 350’000 years, microbes have escorted and influenced the evolution of humans. bacteria and viruses escorted Little more than a decade ago we started to realize that we are PART of an invisible and influenced the evolution of microbial world that is around us, as well as I
Slide 6: Traditional Hygiene Concept
Traditional Hygiene Concept Microbes are dangerous! „only dead microbes are good microbes“ each of us lives with it’s ≈ 100 trillion for centuries we considered (100’000 billion) of bacteria, viruses and fungi … humans and microbes as independent HIS MICROBIOME in his gut, upper airways and on his s
Slide 7: Traditional versus Novel Hygiene Concept
Traditional Hygiene Concept Novel Hygiene Concept Microbes are dangerous ! „Our best allies against pathogen microbes „only dead microbes are good microbes“ are their harmless competitors', the commensals“ humans and buildings are part of an ecosystem, dominated by „kill all microbes” is a wrong str
Slide 8: Acquisition of microbiome and immunity in nature
Acquisition of microbiome and immunity in nature NON MICROBIAL MICROBIAL ENVIRONMENT contact inhalation food ENVIRONMENT organic and inorganic microbes materials in skin airways gut in soil, water plants and as floating aerosols aerosols in the air soil, water, plants & inhalation animals & filtrati
Slide 9: Acquisition of microbiome and immunity in buildings
Acquisition of microbiome and immunity in buildings MONOTONE & UN-BALANCED DIVERSE, BALANCED DRYNESS OF AIR AND SURFACES INDOOR MICROBIOME MICROBIOME OF NATURE CLEANLINESS causes multiple diseases – including so called HOSTILE SURFACES only few people realize what’s going on … “old friends microbes”
Slide 10: Quiz: where is our microbiome located?
First question: where in our body is our microbiome located? Answer 1, 2, 3, 4 , 5 or all 1. skin 2. brain 3. intestine 4. kidneys 5. upper airways, nose & mouth Second question: what is the weight of all microbes in the body of a 70kg person? Answer 1, or 2 or 3 1. several milligrams 2. a few grams
Slide 11: Death rate from infections in the USA
In 20th century Death rate of infections fell dramatically … in 21st century rates of infections, immune diseases and because of hygiene improvements … allergies increase, despite hygiene efforts & medical progress 800 Spanish flu 1918 multiple reasons • population growth, urbanisation, mobility • p
Slide 12: Both kitchens have a hygiene problem
Both kitchens have a hygiene problem – a problem with different reasons neglected hygiene exaggerated hygiene too much all surfaces are so clean •dirt that no harmless and •humidity helpful commensals •microbes can survive on these surfaces. not enough •fresh air only resistant, often •body hygiene
Slide 13: Buildings on the microscale
That’s how our buildings look like on the microscale … http://vimeo.com/9005973
Slide 14: HVAC focus on outdoor and indoor air pollution
For decades the focus of HAVAC industry was on preventing OUTDOOR AIR POLLUTION to enter our homes and workplaces … Obstructive pulmonary disease Lung cancer Lower resp. infections (children) Ischemic heart disease Stroke In recent years HAVAC industry focuses increasingly on how to prevent and expe
Slide 15: Contaminants in air and on surfaces
the contaminants in air and on surfaces are “inorganic”, “organic” or “biotic” part of biotic stuff is the “microbiome of the built environment” bacteria, viruses, fungi, protozoa by naked eye by culture method by microscopy genome sequencing we see nothing! dozens of viable thousands of has uncover
Slide 16: Bacteria and fungi versus air humidity
bacteria & fungi air humidity need nutrients & water = gaseous water molecules for growth and reproduction are unusable for bacteria and fungi propagation H = hydrogen H2O O = oxygen C = carbon N = nitrogen organic material in dirt & dust S = sulphur bodily liquids (mucous, saliva … P = phosphorus d
Slide 17: Building environments are stressful for microbes
Building environments are stressful for microbes … Because of lack of water and nutrients („too dry and too clean“). Use of chemicals, disinfectants and antibiotics promote a multi- resistant microbiome that forms …. … biofilms, promotes persisters (temporary stop of metabolism) and spores. The dive
Slide 18: Occupants, microbiome and buildings as an ecosystem
Occupants, microbiome and buildings must be handled as an ECOSYSTEM bacteria viruses fungi protozoa as in any ECO-SYSTEM diversity, competition and resources decide on stability and sustainability
Slide 19: Ecosystem demands of humans and microbes
human demands for Occupants, microbiome and buildings bacterial & fungi physiology and health demands for a must be handled as an diversified microbiome comfort climate (T, RH) pollutant free breathing air ECOSYSTEM liquid water nutrients = dirt bacteria viruses fungi protozoa rel. humidity should a
Slide 20: Where do wet and dry aerosols containing microbes come from?
Where do “wet” and “dry” aerosols containing microbes come from? wet aerosols wet aerosols dry aerosols wet & dry aerosols + suspended microbes + suspended microbes carrier particles + microbes + microbes from bodily fluids (airways, from wet areas + plants from shedding of skin flakes, from window
Slide 21: Indoor Air Quality (IAQ)
building technology building envelope HAVAC material properties: mass (inertia), ventilation concept (natural, insulation, storage capacity mixing or displacement) for heat & water (sorption) heating, humidification surface properties: roughness, → indoor climate (T, RH) hygroscopicity, porosity “ai
Slide 22: Ventilation impacts on aerosols
building technology Ventilation impacts building envelope HAVAC on aerosols “dilution & extraction” factors with efficiency: 1st cross ventilation impact on IAQ 2nd displacement vent. 3rd mixing vent. ① ① Ventilation impact water uptake by “re-suspension” porous materials (sorption) “PM number conce
Slide 23: Humidity impact on aerosols: low humidity
shrinking of aerosols ↑ floating time ↑ sedimentation velocity ↓ → microbes conserved in drying droplet nuclei humidity impact on → infection risk ↑ ① aerosols ①,② up water uptake by porous materials ↓ aggregation of aerosols “capillary condensation”↓ dryness stress on ④ air ② (in air) ↓ →sedimentat
Slide 24: Humidity impact on aerosols: high humidity
shrinking of aerosols ↓ floating time ↓ sedimentation velocity ↓ → microbes inactivated in hyper saturated droplets humidity impact on → infection risk ↓ ① aerosols ①,② up water uptake by air porous materials ↓ aggregation of aerosols “capillary condensation”↓ ④ contaminants ② (in air) ↑ dryness str
Slide 25: Quiz: consequences of low indoor humidity
Third question: consequences of low indoor relative humidity are: (All statements may be true or false) 1. increased diversity of the microbiome 2. increase of re-suspension 3. decreased floating time of aerosols 4. increase of multi-resistant bacteria Fourth question: almost all natural materials d
Slide 26: Doc's prescription for a healthy microbiome
Doc’s prescription for a diversified, balanced and healthy microbiome in resident and office buildings: o use more natural materials for buildings and interiors especially on walls and ceilings o don’t exaggerate cleanliness – no surface disinfection outside hospitals – cleaning with water and soap,
Slide 27: My wish list
My wish list to in the interest of maintaining health of building occupants, employees and customers • should engage for CO2 controlled mechanical ventilation of public buildings this would allow to save up to 50% of total energy consumption needed for climatization. Moreover it prevents increasingl
Slide 28: Wish list: surface temperature, air currents and ventilation concepts
• should engage for surface temperature measuring of enclosing outer walls and windows in order to detect radiant asymmetries of more than 3-4 degree. These asymmetries reduce occupants comfort despite adequate air temperatures and may allow condensation in winter when below dew temperature. • shoul
Slide 29: Scofield-Sterling diagram: optimal humidity range
The well known Scofield-Sterling diagram states that the optimal humidity range for minimizing adverse health effects is 40 to 60% In midrange humidity 40-60% all epidemic pathogens with winter seasonality have their highest inactivation rate and therefore the shortest infectivity. This applies to f
Slide 30: Survival time of SARS-CoV-2 in aerosols by humidity
«survival time» of SARS-CoV-2 viruses in humidity between 20 to 70%, in aerosols Dep. of Homeland Security Estimated Airborne Decay of SARS-CoV-2 (virus that causes COVID-19) temperature: 10⁰C - 30⁰C rel. humidity: 20 % - 70 % under a range of temperatures, relative humidity, and UV index https://ww
Slide 31: Reference: temperature and humidity effect on virus stability
Morris DH et al, The effect of temperature and humidity on the stability of SARS-CoV-2 and other enveloped viruses
Slide 32: Thanks for your attention
My forecast for the Corona-winter 2020/21 Implementation of the meaningful recommendations of HAVAC associations will confront the population with the driest winter for decades – with yet unknown consequences increased air change in buildings CO2↓ RH↓ where is the optimal combination? increased infe