Two UV lamps were positioned oppositely inside the tube. In a dusty environment, airborne E. coli can be carried by dust particles which prevent UV light from irradiating E. coli. Placing two symmetrical UV lamps can increase the UV irradiance exposure to E. coli. The UV light intensity distribution of one and two UV lamps simulated by UVCalc software is shown in Figure 3. The distributions of UV intensity were not uniform. With one UV lamp installation, the UV fluence rate decreased as the distance away from the UV lamps increased. The overall means of UV irradiations in the central plane were 3687 µW cm −2 and 7434 µW cm −2 for one UV lamp and two UV lamps, and in the total scrubber were 1707 µW cm −2 and 3422 µW cm −2 for one UV lamp and two UV lamps, respectively. The UV fluence rate measurement was validated by the UV light meter at different distances away from the UV lamps. A total of 12 points at different distances were measured for each UV lamp setup. The average fluence rate of the 12 points measurement were 4884 µW cm −2 and 9860 µW cm −2 for one and two UV lamps. The average fluence rate of 12 points with the corresponding distances calculated by the model is 5048 µW cm −2 and 10,869 µW cm −2 . The relative accuracy of the measured **data** and the **data** taken from the model has a difference of about 3% and 9% for one and two UV lamps, respectively. This shows the reliability of the model as the UV light meter has an accuracy of ±5%. In two UV lamp setup, there is a difference of more than 5% compared to the model data. This can be explained by limitations in the measurement process. UV meter sensor can only cover a certain irradiance angle. Therefore, when measuring the UV intensity of two lamps symmetrically positioned on wall, it will not be able to cover the entire incident light, leading to a slight decrease in fluence rate. In one UV lamp setup, the UV meter sensor cover the irradiance angle better than in two UV lamp setup, making a better accuracy rate.