Using Germicidal UV light in a healthy building plan

What is Indoor Air Quality?

Indoor Air Quality (IAQ) has become an increasing focus in building design over the past decade but especially with the rise of the COVID-19 pandemic that threw the topic into the global limelight. Developing an enhanced IAQ plan for an entire building or indeed an interior space such as a spa, office, apartment or gym is likely going to combine a number of key components, including:

• high-grade in-duct filtration

• adequate ventilation rates

• healthy non-toxic building materials

• air purifying plants

• green cleaning policies

• air quality monitors

• IAQ certification

what is UV-C light and UV Germicidal Irradiation (UVGI) in healthy buildings?

UV-C light and UV Germicidal Irradiation (UVGI) can be used to disinfect air, water, and surfaces, thereby lowering the spread of viral infections and bacteria in building interiors. 

UV light is a relatively new but well established technology that can be leveraged as part of a healthy building and interiors plan to improve indoor environmental quality, especially in the post-Covid era.

UV-C lighting can be used on scales as small as individual cabinets to sterilize cellphones or in personal water bottles, all the way up to its incorporation into a building’s HVAC system for a more building level, systematic approach.

Surfaces, air, and water can all benefit from UV-C light technology, although installation and safety should be considered, especially when put in place at the building scale. 

Ultraviolet (UV) light in healthy building cleaning protocols - HML publication

The Parsons Healthy Material Lab (HML) and MFA Lighting Design programs published a doc showing their research and testing of the impacts of Ultraviolet (UV) light on viral spread.

In the wake of the global pandemic, there has been a mindset shift recognizing the importance of a healthy building interior. However, traditional disinfectants commonly contain antimicrobials and other toxins that cause a variety of negative health impacts. ‘Antimicrobial’ does not in fact mean ‘healthy’.

Since the start of the pandemic, aerosol disinfectant spray sales have gone up by 385%, which has the potential to increase health issues of building occupants in other ways.

Parsons concentrated their study on applying UVGI light safely and affordably, focusing most closely on air quality in shared spaces for this very reason.

What is Indoor Viral Transmission in buildings?

Viral spread indoors is a hot topic in the COVID-19 age but is not a new concept per se. Viruses can spread both through the air in the form of small, suspended droplets, or fall to the ground and rest on interior surfaces, as many of us have come to understand in the past few years.

In the air, these droplets are known as aerosols and the virus can be transmitted through inhalation. When the droplets make their way to surfaces, the virus spreads through tactile means. 

How does UV light disinfect building interiors?

An important distinction to make early on is the difference between disinfection and cleansing. Disinfection can be done by UVGI, meaning it kills germs in the air and on surfaces, but doesn’t remove the bacteria and dirt itself.

When combined with cleansing, aka the physical removal of impurities, UVGI implementation is a healthier, safer alternative to traditional aerosol-based disinfectant strategies. 

UVGI specifically refers to a light with the wavelength of 254 nm, which is the application of UV-C radiation for germicidal purposes.

The UVGI system essentially inactivates viruses and bacteria after they are exposed to doses of the light source. The light does this by changing the structure of the DNA and RNA within the microorganism, making it unable to grow and replicate in an infectious manner. 

In interiors, air is carried up from the occupied area to the UVGI element through fans and ventilation. When the air reaches the fixtures, it is then sterilized and can be returned to the occupied area in a healthier, safer condition.

Safety & Installation Considerations of UV-C light

Direct exposure to UV-C light is unsafe for humans, as the radiation can cause a burning sensation similar to a sunburn in the eyes. In addition, material health can be compromised and impact human health if not considered in the design phase. 

Due to human sensitivity to the UVGI wavelength, the lights must be installed in a diffuse manner, avoiding any down-facing, direct light sources. Strategies such as installing UV lights within the HVAC system and upward facing fixtures far above human head height are safe options.

Although the inclusion of UVGI light is a safer alternative to traditionally used disinfectants, care must be taken in fixture type and placement. 

UV-C light can also degrade materials if the relationships are not considered beforehand. Generally, the UVGI wavelength will only superficially penetrate a material, which is nothing to be concerned about.

However, materials such as plastics and polymers are more easily damaged and can off-gas toxic chemicals and carcinogens when in contact with UV light.

Source:

https://healthymaterialslab.org/projects/improving-occupant-health-with-germicidal-uv-light