UNCLASSIFIED

Using 222-nm Ultraviolet (UV) Light forContinuous Disinfection
DSIAC Webinar Briefing

Part 1 – 222 nm Technology

Source: Boeing nonproprietary

Source: Boeing nonproprietary

Q1-2021BOEING is a trademark of Boeing Management Company.
Copyright © 2011 Boeing. All rights reserved.

Copyright ©2021 Boeing. All rights reserved

Jamie Childress

Technical Fellow
jamie.childress@boeing.com(253) 657-6215
Boeing Research and Technology222-nm UV - Bottom Line, Up Front
Boeing Research & Technology• The 222-nm UV is both safer and more effective than longer
wavelength mercury lamps and LEDs.
• This allows continuous disinfection in occupied areas.
 Not possible with older UV systems.

Why?

• The 222-nm UV is safer and more effective because it is highly
absorbed by both protein and DNA.
• Longer wavelength UV is not strongly absorbed by protein.

Source: Boeing nonproprietary

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

2

A Very Brief History of UV Disinfection
Boeing Research & Technology• The germicidal properties of UV light have been
known since the 1930s.
• Early UV disinfection and the majority of UV
disinfection today are done with mercury vapor
lamps, which have strong emissions at 254 nm.

254 nmmercurylamp

Source: Wikimedia commons• In recent years, LEDs that emit at useful germicidal
frequencies between 260 and 280 nm have gone into
mass production.
• Recently, a new type of UV disinfection technology hasemerged using excimer lamps that emit at 222 nm.
 This 222 nm technology is game changing.

UV LED

Source: Boeing nonproprietary

222 nm excimer
Source: Boeing nonproprietary

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

3

UV Light Spectrum
Boeing Research & Technology

Electromagnetic Spectrum

222-nm light falls in aunique part of thespectrum below thefrequencies of mercury
lamps and current UV
LEDs.
VisibleSpectrum

Source: Boeing nonproprietary

254 nm mercury lamps & LEDs
222 nm excimer lamps
Source:Boeing nonproprietary

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

4

222 nm Excimer Lamps
Boeing Research & Technology• An excimer lamp is a glass bottle filled with gas that has
high-voltage electrodes along its length.

222 nm excimer• A high-voltage discharge between inner and outer electrodes
creates a “temporary” molecule that rapidly decays.
Lightning in a bottle This “temporary” molecule decay creates the light.

• Excimer lamps typically operate at thousands of voltsand more than 10,000 Hz.

1.0

Typical Kr/Cl
excimer emissions

Irradiance The gas mixture determines the light frequency
created by this molecular decay.

Source: Boeing nonproprietary

230 nm lowpass filter0• Kr/Cl excimer (exciplex) lamps primarily emit light at 222 nm.

Wavelength (nm)
Source: Boeing nonproprietary• 222-nm LEDs are in research, but none are in mass
production.

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

5222-nm UV Is Absorbed by DNA and Protein.
Boeing Research & Technology

222-nm UV has unique properties and is NOT the sameas mercury lamps or UV LEDs.

•

222-nm UV is highly absorbed by both protein bondsand DNA.

•This protein absorption makes 222-nm UV safe forhuman exposure.

•Mercury lamps and UV LEDs use UV-C between
250 and 280 nm.

•

250–280-nm UV has low absorption by protein.

•UV-C in the 250–280 nm range is carcinogenic andcannot be used on occupied areas.

222 nm1254 nmDNA0.1

Absorbance

•

0.01

Protein
0.001
220300260 280
Wavelength (nm)

240

320

Source: Boeing extrapolation of Harm et al.,1980• Protein has 25 times better absorption of 222 nm compared to 254 nm.
• DNA absorption is similar for both frequencies.
Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

UV Transmittance of Mouse and Human SkinBoeing Research & Technology
Wavelength (nm)

100% 102

200220240260

280300320340360• Estimated transmittance ofhuman epidermis

101

1%

100

0.03%

10-1
10-2
10-3Transmittance (%)

10-4
10-5
10-6

Light
transmission-9
10 through skin
10-7

10-8

10-10
10-11

254 nm measuredtransmission• ~50% stratum corneum• ~3% epidermis• skin cancer risk
~1 person in 3,000
222 nm measured transmission• ~0.03% stratum corneum• ~0% epidermis• skin cancer risk
<1 person in quadrillion

10-12

254 nm 222 nm
222-nm UV will not
penetrate deadstratum corneum
outer skin layer
because it ishighly absorbed
by protein
basale cells.
Image Source: Wikimedia commons

Human stratum corneum (20 μm)

10-13
10-14

• Measured transmittance ofstratum corneum

Logarithmicgraph

Human epidermis (90 μm)

222-nm UV is safer
than sunlight.

Source: Boeing extrapolation of C. Nisigori, ASP Symposium 2020 data

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

7

222 nm Safety Data
Boeing Research & Technology• Numerous 222 nm exposure studies conducted on bothhumans and animals support the raising of the human daily
exposure limit (TLV) to over 500 mJ/cm2.
• Human and animal skin tests up to 1,000 mJ/cm2, withno adverse effects.
• Animal eye tests up to 600 mJ/cm2, with no adverseeffects.
• Columbia/Brenner lifetime hairless mouse study• Multiple studies of DNA damage to mammalian cells
show that 254-nm light causes increasing DNA damage
in mammalian cells with increasing dosage, but 222-nm
light does not.

600 mJ/cm2 eye exposure

CPD

cyclobutane pyrimidine dimers

50% Cell DNA Damage Study completed 60-week mouse lifetime
 Exposed 8 hours/day, 5 days a week to 500 mJ/cm2
222 nm: no adverse effects detected Post-mortem autopsies and pathology in process Boeing working with Columbia

Image Source: Wikimedia commons

4030254-nm light20
100222-nm light
0150
50100
UV Fluence (mJ/cm2)

Source: Boeing extrapolation of Brenner ICUDAS data

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

8Current Exposure Guidelines
Boeing Research & Technology• No FDA-mandated UV exposure limit.
 (unless used as part of medical device)• Threshold Limit Value (TLV) is a guideline generally
followed in industrial settings.
• The current 222 nm TLV value is based on oldassumptions and does not include new safety data.
• Work is ongoing with regulators to increase the222 nm limit to over 500 mJ/cm2 based upon the newhuman and animal safety data.

ACGIH (American Conference ofGovernmental Industrial Hygienists)
Current Human Threshold LimitValues (TLV) for UV Wavelengths

TLV (mJ/cm2)• UV disinfection devices are regulated by the EPA as apesticide device.

23 mJ/cm 2~6 mJ/cm2~3 mJ/cm2

Wavelength (nm)
Source: Boeing extrapolation of ACGIH TLV data

• This will allow continuous disinfection in short timeframes.
Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

9222-nm UV Is Deadly to All Pathogens.
Boeing Research & Technology

If 222-nm UV is safer for humans, why does it kill pathogens?
• Because pathogen cells are tiny and human cells are large.
• 222-nm UV easily penetrates a few microns into protein.
• 222-nm UV fully penetrates small cells.
 Human cells are about 40 µm in diameter.
• Not fully penetrated by 222-nm UV
 Bacteria & virus are less than 1 µm in diameter.
• Full penetration of bacteria and virus
 Destroys bacterial and virus cell walls and DNA.

Large cells partial
penetration

Image Sources: Wikimedia commons

Microbes are 10X smaller thanhuman cells and are fully
penetrated by far UV.

Corona Virus Inactivation

Viruses and Bacteria Smaller Than Human Cells

Small cells fullpenetration

90%
99%

99.9%

99,99%

Virus100 nmBacteria
1 μm

Plant & Animal Cells
15–80 μm

0HCoV-OC43
1.520.512
222 nm Dose (mJ/cm )Source: Boeing extrapolation of Brenner ICUDAS data

Image Sources: Wikimedia commons

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

10222-nm UV Is Very Effective for Coronavirus.
Boeing Research & Technology•••

Coronaviruses are mostly protein.
Coronaviruses are very small, ~0.1 µm.
Fully penetrated and rapidly destroyed by 222-nm UV.
Spikeprotein

SARS-CoV-2 coronavirus• Required UV dose for 99.9% surface disinfection
 254 nm: ~6.5 mJ/cm2
 222 nm: ~3 mJ/cm2 (222 is twice as effective)• Required UV dose for 90% surface disinfection
 222 nm: ~1 mJ/cm2
HCoV-229E coronavirus• Required UV dose for 99% airborne disinfection
 222 nm: 1.1 mJ/cm2• Required UV dose for 90% airborne disinfection
 222 nm: 0.56 mJ/cm2

Copyright ©2021 Boeing. All rights reserved

Image Source:
Wikimedia commons

Envelope and membraneproteins

Copyright © 2012 Boeing. All rights reserved.

11222-nm UV Is NOT Subject to Photoreactivation.
Boeing Research & Technology• Both 222-nm UV and 250–300-nm UV damage the DNA of the targetedpathogen, which inactivates the pathogen’s ability to replicate.
• Photoreactivation is a repair mechanism pathogens can use torepair themselves after their DNA is damaged by UV light.
• Many bacteria and some viruses have the photolyase genethat allows them to repair DNA using ordinary blue light.
• For some pathogens, 250–300-nm UV damaged DNA can be repairedin as little as a few hours' exposure to blue light (reactivating them).
• 222-nm UV is not subject to photoreactivation since both DNA
and the cell wall are destroyed.
 No reported photoreactivation of 222 nm inactivated microbes.
Image Source:
Wikimedia commons

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

12

Applications of 222 nm Technology
Boeing Research & Technology• 222 nm technology is the preferred system when disinfecting occupied areas.
 Allows continuous disinfection in occupied areas
 Highly effective Optical power can be dialed up or down as needed
Examples:• Rapid disinfection
 High power mobile 222 nm wand• Automated periodic UV disinfection
 Boeing clean lavatory• Persistent UV disinfection
 Continuous disinfection of occupied areas

Source: Boeing nonproprietary

Source: Boeing nonproprietary

Copyright ©2021 Boeing. All rights reserved

Copyright © 2012 Boeing. All rights reserved.

13

Part 2 – 222-nm Disinfection Lighting
DSIAC Briefing
DoD Applications and Installations of Continuous 222-nm Disinfection Lighting
PJ PiperCEO
Far UV Technologies, Inc.
pjpiper@faruv.com(917) 885-8516

March 2021

UNCLASSIFIED

Current Applications of the 222-nm Disinfection Lighting
Far UV Technologies15Current Applications of the 222-nm Disinfection Lighting
Far UV Technologies

16

Other Civilian Applications
Elderly CareDay CareRestaurants/RetailFerries/Cruise Ships
TrainsCity Halls

Museums
Theaters
Hotels - Casinos