airpointer®Ozone (O3)
About Ozone
Ozone is a highly toxic corrosive substance and a common pollutant. Ozone is formed in the atmosphere by reaction of nitrogen oxides, hydrocarbons, and sunlight. Some kinds of electrical equipment, e.g. television sets, photocopiers and electric motors (which use brushes), generate such an amount of ozone that a person can easily smell it.
Health and Environmental Effects
Acute effects include respiratory symptoms, changes in pulmonary function, increased respiratory sensitivity and respiratory inflammation.
Ozone damages the leaves of trees and other plants (photooxidation), ruining the appearance of cities, national parks, and recreation areas.
Sources: WHO Regional Publications, European Series, No. 91, "Air quality guidelines for Europe", 2nd edition, 2000;
GESTIS Stoffdatenbank (http://www.hvbg.de/d/bia/fac/stoffdb/index.html); U.S. Environmental Protection Agency (www.epa.gov)
Ozone and the airpointer®
Measuring Principle: Ultraviolet Photometry (EN 14625)
O3 / Ultraviolet Photometry
From a high energy UV lamp a beam goes alternately through two tubes, which are filled with the sample gas alternately with the ozone sample and with a sample where the ozone is filtered. The decrease of the light's density, resulting from the presence of ozone, is measured with two detectors at the end of the tubes. Two-path design ensures correction of possible changes in light intensity.
A zero air source is included in every airpointer®, so a zero point check can be performed periodically e.g. once a day. An internal ozone generator is optionally available for a periodical span point check.
| Component | Ozone O3 |
| EU Directive / EPA Methodology | Ultraviolet Photometry (EN 14625) |
| Measuring Principle | Ultraviolet Photometry |
| Range | Dynamic up to 20 ppm |
| Zero Noise | 0.25 ppb RMS |
| Lower Detectable Limit | 0.5 ppb |
| Zero Drift (24Hour) | < 1 ppb |
| Span Drift | +/- 1% of reading or 1ppb (whichever is greater) |
| Response Time | < 30 seconds |
| Precision | 1 ppb |
| Linearity | +/- 1% of reading > 100 ppb |
| Sample Flow Rate | approx. 1000 ml/min |