Great to see everyone at the 2014 ISM in Grindelwald!
Control of Temperature and Humidity in Hospitals
Temperature and relative humidity affects the airborne survival of viruses, bacteria and fungi. Thus environmental control in hospitals is important because of infectious disease transmission from the aerosol or airborne infection.
Environmental exposure is a common hazard for all such organisms (whether viruses, bacteria or fungi) during this journey between hosts. Factors such as temperature, humidity (both relative and absolute), sunlight (ultraviolet light) exposure and even atmospheric pollutants can all act to inactivate free-floating, airborne infectious organisms.
Maintaining hospital premises at a certain temperature and a certain relative humidity (%rh), likely to reduce the airborne survival and therefore transmission of influenza virus. Temperature and RH settings in different parts of a hospital differ slightly between summer and winter. In summer, the recommended room temperatures range from 23°C-27°C in the ER (emergency room), including in-patient and out-patient areas, as well as X-ray and treatment rooms and offices. The corresponding recommended RH is fairly constant throughout the hospital, between 50- 60%rh. In winter, the recommended temperatures are generally slightly lower, ranging from 20°C in some in-patient and out-patient areas, as well as offices, up to 24°C -26°C in in-patient and out-patient areas.
The recommendations for the newborn baby and the hydrotherapy treatment rooms are higher at 27°C –28°C. Again, the corresponding recommended range of RH is fairly constant, but slightly lower than for summer, ranging from 40%rh -50%rh, but up to 55%rh–60%rh for more critical areas, such as operating theatres and recovery, the intensive care unit and childbirth/delivery suites.
Temperature is one of the most important factors affecting virus survival, as it can affect the state of viral proteins and the virus genome. Virus survival decreases progressively at 20.5°C –24°C then < 30°C temperatures. This relationship with temperature held throughout humidity range of 23%rh- 81%rh.
Facts & figures:RH (expressed in percentage) describes the amount of water vapor held in the air at a specific temperature at any time, relative to the maximum amount of water vapor that air at that temperature could possibly hold.
At higher temperatures, air can hold more water vapor, and the relationship is roughly exponential—air at high temperatures can hold much more water vapor than air at lower temperatures.
Why do we need to measure relative humidity?
Virus: The survival of viruses and other infectious agents depends partially on levels of RH. At a temperature of 21°C, influenza survival is lowest at a mid-range 40%rh–60%rh. It is also important to note that temperature and RH will always interact to affect the survival of airborne viruses in aerosols.
At High temperatures < 30°C and at high RH < 50%rh may reduce the survival of airborne influenza virus.
Bacteria : For bacteria, the effect of carbon monoxide (CO), enhanced the death rate at less than 25%rh, but protects the bacteria at higher RH ~ 90%rh.
Temperatures above about 24°C appear to universally decrease airborne bacterial survival.
Fungi: Ventilation systems controlling Temperature and Humidity have a significant effect on indoor levels of airborne fungi, with air-handling units reducing, but natural ventilation and fan-coil units increasing the indoor concentrations of airborne fungi.
Dehumidification as well as HEPA filtration can be used to improve indoor air quality.
Different airborne infectious agents (i.e. viruses, bacteria and fungi) will have differing conditions under which they may be optimally suppressed; it will need to be decided which airborne pathogen poses the most risk to patients and staff alike in hospitals.
Thus, in reducing infectious disease transmission specific environmental control of temperature and humidity is vital for hospitals and healthcare premises.
Rotronic can offering a complete system for hospital measurement applications: a proven system that enables healthcare facilities to control and monitor their conditions and remain in conformance with internal or regulatory guidelines.
With the combination of both analogue outputs, controlling the air-conditioning, and digital outputs, linked up to the Rotronic HW4 monitoring software, end users have a clear overview of conditions.Dr. Jeremy Wingate
The Rotronic HygroGen2 (HG2-S) is known globally an amazing piece of instrumentation. The fastest relative humidity and temperature generator to set point on the market and loved in the pharmaceutical world. The HG2-S has many advantages compared to other chambers and new developments are making the unit even better. With AutoCal+ (direct communication with an MBW/RHS 473 Chilled Mirrors) and Remote Control (HG2-S control any web enabled device) more and more possibilities are available.
Our HQ Rotronic AG has invested into After Sales and today, like Rotronic Germany are offering more and more on-site calibration. With the HG2-S, it is possible to offer a fast and efficient calibration with direct delivery of calibration certificates and direct repairs on-site when necessary
A short story is available on our Swiss HQs Blog (only in German). As seen in the photo, in order to deliver a very quick turnaround (30 probes, within 4 hours) three HG2-S units were used at fixed temperatures and relative humidity levels. Return of investment is quickly achieved with the HygroGen through the ability to provide fast, high quality calibrations. If you are interested in setting up your own on-site calibration service, let us know, we will be happy to help!
With the new AutoCal+ function and the MBW 473, you can reduce the uncertainties of your setup and with the remote function, you can multitask and work more efficiently.
All information for the HygroGen2 Humidity and Temperature Generator is available on the Rotronic website.
If you have any questions about the HygroGen2 please do not hesitate to contact us!Dr Jeremy Wingate
Thorne and Derrick have written a great blog post on the importance of quality measurement and control in cheese manufacturing (a key industry for Rotronic sensors due to their reliance to the high humidity conditions in cheese maturing!)
Check out the post here…
Thorne and Derrick are national distributors and worldwide exporters of process & mechanical equipment.
Would you like us to share your blog posts on measurement or humidity? Please contact us!Dr Jeremy Wingate
Bread – The stuff of life!
Most of us have a never ending choice of the most delicious breads, cakes and pastries to please both the palate and the eyes. We have become so used to this diverse range of bread and baked products, but do you how bread originally came into existence?
The interesting history of what is now called the “staff of life”, bread, and the making of it, started in comparatively recent times.
At the very beginning of recorded history there was the discovery of fire making and thus along with light, heat could be generated. Then it was found that different grasses and their seeds could be prepared for nourishment.
Later, with the combination of grain, water and heat, it was possible to prepare a kind of dense broth. Hot stones were covered with this broth or the broth was roasted on embers and “hey presto” the first unsoured flat bread was created. This ability to prepare stable food radically changed the eating habits and lifestyles of our early ancestors. They progressed from being hunters to settlers.
Facts & figures:
- Records show that as early as 2600-2100 B.C. bread was baked by Egyptians, who it is believed had learned the skill from the Babylonians.
- On average, every American consumes around 53 lb (24 kg) of bread per year.
- The “pocket” in pita bread is made by steam. The steam puffs up the dough and, as the bread cools and flattens, a pocket is left in the middle.
- US Farmers receive just 5 cents (or less) for each loaf of bread sold.
Why the need to measure humidity?
The production of baked goods such as bread, cakes, biscuits and pastries requires a number of processing steps in which humidity and temperature play an important role.
After mixing, it is typical to divide the dough into pieces and allow it to rest for a few minutes so that the gluten network in the dough can relax allowing easier moulding, which is the next step.
If at that stage, the temperature is too hot the dough will be too sticky and cannot be easily processed further, if too cold the dough can become damaged during moulding which leads to holes forming in the bread. If the humidity level prior to the moulding process was too low a skin of dry dough can form on the dough surface. This makes it harder for the dough to increase its volume during the next
process step called proving.
Proving is the professional term for the final dough-rise step before baking, where 90% of the bread volume is achieved. To achieve consistently good dough rising results special chambers are used. These chambers can maintain the ideal environment for the yeast to grow. Depending on the yeast and flour used, temperatures between 38…42°C and humidity levels between 70…80%rh are considered ideal.
In summary, the use of quality ingredients and careful handling throughout the various stages of production will not result in a quality product unless the dough temperature, and the temperature and humidity of the bakery are carefully regulated. Modern day bakeries use custom ventilation systems that are controlled by precision humidity and temperature sensors.
So once again the behavior of the humble water molecule is to blame! In this case for the stricken faces of The Great British Bake Off contestants as they stress about the quality of their crust and whether the dough will be cooked through to perfection!