Commonly found air pollutants, or "criteria pollutants", include particulate matter, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides and lead. Exposure to ozone, at even relatively low levels, is harmful to health resulting in reduced lung function and aggravating pre-existing respiratory conditions. Considering that ozone is also used in industrial applications in processes as varied as semiconductor cleaning to water purification, monitoring of ozone levels is critical.

UVC light is strongly absorbed by ozone and this absorption can be used to quantify the amount of ozone in the air. Traditional UV lamp systems have several limitations such as the requirement of a long optical path length to achieve high sensitivity and a high voltage to initiate the discharge. This precludes their use in mobile and handheld devices. This is also true of ozone sensing by metal oxide thin films which require a high operating temperature and consume relatively higher power.

Ground-level ozone is one of the most commonly found air pollutants created by chemical reactions between oxides of nitrogen and volatile organic compounds in the presence of sunlight. Considering the extensive range of health hazards it imposes, the current EPA ozone standard is set at 75 parts-per-billion (ppb) underscoring the critical need to monitor ground level ozone in the parts- per-billion level. Absorption of UV light at 255 and 280 nm can be used to quantify the amount of ozone in the air.

Crystal IS UVC LEDs offer advantages in these applications.
  • Stability of light output allows for more accurate results

  • High light output enables shorter optical path length than traditional UV lamps, providing quick measurements

  • Long lifetime, low operating voltage and small form factor enable use in mobile and handheld devices 

  • Low cost of ownership reduces system costs