Influence of Indoor Air Quality on Our Health
People spend approximately 90 percent of their time indoors, and breathe 12,000 litres of air per day. It is therefore important to understand the powerful influence that indoor air quality has on our wellbeing, especially during this extraordinary time of the coronavirus pandemic. While the impact of volatile organic compounds (VOCs) on humans has been widely discussed within the context of the 'sick building syndrome', the role dry air plays in spreading of microbes, including viruses, is often neglected. High performing HVAC systems and proper humidification strategies are required to maintain a stable and healthy indoor air quality in buildings.
How does humidity affect the spread of viruses?
One way for viruses to spread is within small water droplets. The higher the air humidity, the larger the droplets become, which stops them from travelling as far. Small droplets, on the other hand, can travel through large open office spaces and survive for hours infecting more people. Furthermore, many bacteria and viruses become more virulent when exposed to dry air.
In temperate climates, the humidity of air often drops to a relative humidity of below 40 percent during the colder months. However, the 'sweet spot' for indoor air humidity is 40-60 percent, as this dramatically reduces the risk of disease transmission, and enables the body to better repair and protect itself.
Get ready to be amazed by the power of proper humidification, and learn about the steps you can take to improve your own health, productivity and learning.
ASHRAE Tech Hour: Occupant health, building energy performance and humidity
Presented by Dr Stephanie Taylor, CEO of Taylor Healthcare Commissioning, Inc.
ASHRAE Tech Hour shares the latest technical content presented by some of ASHRAE's brightest minds.
Dr Taylor is a graduate of Harvard Medical School (MD) and Norwich University (Masters Architecture). Her lifelong commitment to occupant health and wellness focuses on indoor physical environments.
How do volatile organic compounds affect human health?
VOCs are organic chemicals – such as formaldehyde and benzene – and originate from many different sources, including perfumes, paint, carpets, building materials and smoke. They are a significant contributor to 'sick building syndrome' (a condition that's thought to be caused by being in a building), and have an impact on the wellbeing of occupants. Even low VOC concentrations can cause irritation to mucous membranes (eyes, nose and respiratory tract), as well as headaches, fatigue and nausea. High concentrations of certain VOCs can also lead to other health issues. For most chemical compounds, local authorities set maximum values for VOC concentrations in workplaces, which can be measured directly, and controlled by appropriate ventilation and air purification.
Why central air treatment systems create a healthier indoor air climate?
Central air handling units (AHUs) and air distribution systems are able to provide fresh, filtered and conditioned air to the zones of a building rather than recirculating used air inside a room. The advantage of this approach is that the quality of the supplied air can be centrally controlled in an AHU at any time. Temperature and humidity sensors permanently measure the thermal conditions of the supplied air and deviations are instantly detected and corrected. Pressure sensors over the filters will early on detect the need for a filter change, making sure at all times that only a minimum amount of dust reaches the inside of the building. All the zones supplied will benefit from high comfort and safety.
In addition to central control of the air quality in the AHU, the indoor air conditions can be individually measured and controlled in each room. Room sensors, which could permanently measure all parameters around us, such as temperature, humidity, CO2 and the presence of VOCs (volatile organic compounds), are essential for our health and well-being. An increase in the CO2 or VOC concentration in the room, for example through the presence of many people in the room or a copy machine creating extra emissions, will instantly be detected and the air-damper of the air-duct in the room can be opened to provide more fresh air into the respective room. This will instantly bring the comfort level back to a healthy level.
You can only control what you can measure. This also applies for indoor air quality. Sensors amount to only 0.08% of the total HVAC investment in a building. The cost of using reliable and accurate sensors are quickly paid back by improved health and productivity of the occupants.
Furthermore, proper commissioning and maintenance is an important step to assure long-term stable, accurate measurement and control.
Reliability is the foundation
Reliable and high-quality sensors are the foundation of the HVAC system to provide a healthy, productive and comfortable environment. Many sensors on the market are known to drift over time. Belimo's humidity sensors with Polymer Capacitive Sensing element are not affected by high humidity and contaminants. They are 2% accurate as standard and have a long-term drift of only <±0.25%. High accuracy and long-term stability are the prerequisite for ensuring the optimum air quality levels.
Belimo supplies a complete range of sensors. The new Belimo room sensors ensure a user-friendly experience with easy installation and timeless design. In addition, Belimo Assistant App allows fast commissioning and diagnostics easily via a smartphone.
Visit regional website for more information about our sensors:
A study on the influence of air quality in schools
The MeineRaumluft.ch platform joined forces with the Zurich Teachers' Association (Züricher Lehrerverband) and the Zurich Lung Organization (Organisation Lunge Zürich) to discover how air quality affects pupils and teachers. In November 2016, MeineRaumluft.ch installed measuring devices in over 250 classrooms.
Read the study to see how simply installing these measuring devices affected the ventilation habits of teachers and pupils:
Controlled air conditions in isolated rooms
The transmission of pathogens can be prevented by isolating or physically separating one or more persons from other parts of society. In hospitals, special isolation rooms are established to protect people and their surroundings.
Isolation rooms are operated with a negative or positive room pressure ratio with regards to their surroundings. The new, modular structure of the VAV-Universal controller product range makes it easy to create the ideal combination of volumetric flow and room pressure control that is precisely matched to the respective zone.