Table 2.
Comparison of the measured concentrations of ozone and nitrogen oxides (mean±SD) as ppm in the breathing air of welders with standard permissible exposure limit in TIG and MIG welding.
| Oxidizing agents | All welders | Control group (n = 41) | Standard ** | Exposure> permissible limit | TIG (n = 20) | MIG (n = 23) | p-value * |
|---|---|---|---|---|---|---|---|
| Ozone | 0.30±0.19 | *** | 0.1 | 88.4% | 0.21±0.12 | 0.37±0.22 | 0.006 |
| Nitrogen dioxide | 3.41±0.63 | *** | 3 | 74.4% | 3.54±0.65 | 3.29±0.60 | 0.21 |
| Nitrogen oxide | 0.52± 3.0 | *** | 25 | 0 | 0.41±2.70 | 0.54±3.20 | 0.006 |
*
Comparison of exposure of welders in TIG and MIG welding
**
Iranian Occupational Hygiene Standard
***
Below the detectable rate of 0.07 ppm for ozone and 0.25 ppm for nitrogen oxides