A customer who does HVAC duct disinfection once complained to me: “After we installed the UV lamps, there was a strange smell in the equipment room and my staff said they felt dizzy.” One look told me exactly where the problem was — he had bought ozone-generating 185 nm lamps and installed them in a sealed space with no exhaust ventilation. Ozone is a powerful tool in the right place, but a safety hazard in the wrong one.
Where 185 nm Comes From, and Where Ozone Comes From
A low-pressure mercury lamp naturally emits two spectral lines, 254 nm and 185 nm. The 254 nm line does the germicidal work, while the shorter-wavelength, higher-energy 185 nm line is absorbed by oxygen molecules in the air and generates ozone. Whether or not you let that 185 nm escape comes down to the quartz the lamp tube is made of.
- Ozone-generating: uses quartz that transmits 185 nm, producing ozone in large amounts. Ozone is a strong oxidizer in its own right; it diffuses into shadowed corners, ductwork and crevices that the light cannot reach, covering the blind spots that line-of-sight disinfection misses, and it is also used for deodorizing and oxidative breakdown.
- Ozone-free: dopes the quartz with a component that absorbs 185 nm (often called titanium-doped or synthetic quartz), letting only the 254 nm germicidal line through and generating almost no ozone — suitable for occupied spaces.
What Happens If You Choose Wrong
Ozone irritates the human respiratory tract, and many countries set strict limits on ozone concentration in the workplace. So installing ozone-generating lamps in an occupied office, classroom or equipment room without exhaust ventilation lands you in exactly the situation that customer was in. Conversely, in a sealed water tank or storage vessel, or in an environment that needs deodorizing anyway, ozone-generating lamps can do twice the work with half the effort — but the space must be unoccupied during operation, and it must be thoroughly ventilated before anyone goes back in, so the ozone has time to decay away naturally.
It comes down to one rule: where people are present, go ozone-free first; only in a sealed environment that relies on ozone for oxidation and can be cleared and ventilated should you use the ozone-generating type.
Not sure which type your site needs, or how to set up the exhaust and safety interlocks? TingHao is based in Kaohsiung and knows factory and equipment-room environments across southern Taiwan. Call us at 07-363-0802 or reach us on LINE — do not let ozone become an invisible risk.