Many organizations have had to completely shut down their indoor spaces or operate under severe restrictions during the COVID-19 pandemic. Although there is eagerness among businesses to reopen, many stakeholders continue to be concerned about worker safety, especially in office spaces, where the novel coronavirus is known to spread rapidly.
Over the past year, we have received questions from multiple innovators regarding indoor sanitization technologies. In this blog, we discuss the underlying technology, pros and cons, and key vendors for the three most promising indoor sanitization technologies – bipolar ionization, UVC, and cold plasma.
Bipolar ionization uses ionized gas molecules to attract particles and gaseous chemicals and then reacts with the organic compounds and gaseous chemicals. The chemical reactions decompose the compound and deactivate the virus, thus removing odors and sterilizing the air. Research has demonstrated that ionized air can effectively deactivate the virus (>97%) and prevent infections when implemented properly.
Typically, air flows between two electrostatically charged plates; this process produces positively and negatively charged gas ions. Generally, the method is optimized for generating ionized O2+ (superoxide) and O2−. The positively and negatively charged oxygen molecules deactivate the virus through oxidation reactions and effectively remove odors. However, the process also generates a small amount of O3 (ozone), which is a very powerful oxidant and can pose serious long-term health risks, especially at high amounts of exposure. Fortunately, ozone can easily be removed via specialized filters, thereby minimizing the risk of ozone exposure.
A few companies offering bipolar ionization-based indoor sanitization products include:
- TrumpXP (Lux Take: Wait and See) – Develops negative-ion air purifiers with a smaller ozone side effect, as low as 0.01 ppm, and a longer lifespan between 8,000 hours and 10,000 hours, which is competitive with local and international players.
- LifeAir (Lux Take: Caution) – Develops an air purifier that uses electrostatic precipitation; the proprietary (and patent-pending) design is able to generate ions without generating ozone, and the system is capable of removing ultrafine particles down to the size of PM 0.3.
- Plasma Air – Offers air ion generators that can be integrated into the HVAC systems of commercial buildings and industrial manufacturing facilities. The company claims its industrial ionizer (size: 0.66 m × 0.23 m × 0.21 m) can process ~17,000 m3/h.
- Airionex – Offers industrial-level bipolar ionization solutions, targeting office spaces, manufacturing, and transportation air purification use cases.
- Indoor Air Quality Associates – Claims it offers ozone-free bipolar ionization technology; unfortunately, it is unclear how it achieves ozone-free operation.
UVC refers to ultraviolet C light, which is high-energy electromagnetic radiation with wavelengths between 100 nm and 280 nm. UVC radiation can quickly kill bacteria, viruses, and other microorganisms, although there are concerns about its effects on the human body. Although attenuation in air and absorption by dead skin cells minimize the amount of UVC radiation reaching live cells, there is not sufficient evidence to rule it out as a potential carcinogen. However, short-term usage may mitigate the harm from UVC, considering its high efficiency in sterilization.
Example companies include:
- Eden Park Illumination – Offers thin 222 nm UV lamps for large-area disinfection applications. Unlike its competitors' offerings, its lamps are flat and thin. The company aims to let the users keep the lamps on in occupied spaces, as 222 nm UV cannot penetrate human skin, making it safe for human beings. Eden Park claims that the lifespan of its lamps ranges from 2,000 to 6,000 hours. In addition, Eden Parks offers lamps using 172 nm wavelength, 308 nm wavelength, and phosphor lamps. The company aims for the lamps to be used in offices, restaurants, and public spaces. It needs to be careful about its claims and targeted method of using the lamps.
- Tru-D – Develops UVC light for the hospital environment. While many UVC developers emphasize the compact size and occupant-friendly features, Tru-D emphasizes excellent efficacy and efficiency. The company uses continuous UVC light and claims full-scale sanitization without requiring moving UVC lamps around. In addition, Tru-D claims its UVC disinfection systems automatically monitor the dosage of UV light in each room to ensure a lethal dose of UVC for disinfecting the entire room.
- Bioclimatic – Offers two types of technologies: UV and UVC for surface and air disinfection and an air ionizer for air sanitization and purification.
- Yanfeng – An automotive interior system company whose main business is developing interiors and devices used in passenger car cabins. The company developed overhead antimicrobial devices for in-cabin use cases. The device combines a nonliquid scent-dispensing system and a UV air sanitizing system. The UV sterilization technology uses UVC light to kill bacteria, viruses, and other microorganisms in the air and on surfaces.
- Lukirch – Develops small sanitizing electronics. Its rechargeable UV sterilizers are designed for in-cabin sanitization uses. The device uses UVC light and ozone to kill the microorganisms in the cabin. It claims the disinfection process only takes several seconds.
- Medklinn – Based in Malaysia, the company develops personal electronic air cleaners with dedicated products for auto applications. Its in-car sterilizers use ozone to sterilize the air and surface of the car. Ozone can oxidize microorganisms quickly, thus deactivating them. The devices use standard 12 V outlets in cars as power sources.
Cold plasma (nonthermal plasma)
Cold plasma refers to plasma that is not in thermodynamic equilibrium. It contains extremely high-temperature electrons and slightly above-room-temperature heavy species (ions and neutrals), making the overall temperature barely above room temperature. It uses ions, electrons, reactive oxygen species, reactive nitrogen species, and byproduct UV to sterilize objects. The active agents physically break the bonds in organic compounds to deactivate pathogens and decompose organic chemicals.
- Terraplasma – Develops sanitization devices using cold plasma. The devices are designed to sanitize the surfaces of consumer goods that can be contained within the plasma generators.
- Plasmology4 – Develops a cold plasma platform for healthcare applications. The company uses plasma to disinfect wounds. It has received recognition from the FDA.
The three technologies have different pros and cons. Bipolar ionizers are suitable for indoor atmospheric sanitization applications. They are effective when installed in air circulation or ventilation systems. However, using the technology involves potentially complicated installation and high upfront costs. UVC is convenient and flexible for different environments, such as large rooms, small boxes, or professional labs. However, due to safety concerns, UVC is usually limited to sanitization in unoccupied indoor spaces. Cold plasma appears to be limited for disinfection use cases in relatively small spaces and could potentially suffer from scalability issues, thus limiting the application scale.