Particle size distributions inside a university office in Amman, Jordan

Abstract EN

We studied the number based particle size distribution (diameter 0.3-10 μm with high time-resolution) inside an office (naturally ventilated) at a university building in Jordan during two weeks (18.09.2013-01.10.2013).

We analyzed and investigated the particle number and mass concentrations, their differences between workdays and weekends and the effect of tobacco smoke and worker activities inside the office.

We also focused on three scenarios of office conditions : totally closed, totally open and open window.

The 24-hour means of the PM10-0.3 were 16.4-43.2 μg / m3 on workdays and 4.4-8.5 μg / m3 on weekends.

The concentrations ranged from 4.3 μg / m3 to 7.7 μg / m3 (30.0-42.1 cm-3) when the office was kept closed at nighttime and weekends.

They also ranged from 5.2 μg / m3 to 25.8 μg / m3 (50.0-83.2 cm-3) when the window was open at night.

The highest concentration ranged from 2.5 μg / m3 to 261.9 μg / m3 (15.5-906.4 cm-3) during the daytime on workdays when the office was open.

The variation of aerosol concentrations is believed to be caused by increased urban activities on daytime and workdays, enhanced ventilation rate and penetration factor when the office was open, and the resuspension of carpet-dust by the office occupants and visitors.

Smoking inside the office increased the aerosol concentration to 3729.2 μg / m3 (4854.5 cm-3) and the tobacco smoke remained sensible inside the office for more than 40 minutes.

Since the mass concentrations presented here were calculated by assuming spherical particles and unit density and the measured sizerange was larger than 300 nm in diameter, the PM10 is expected to be at least double the numbers shown in this study, and thus the 24-hour PM10 in the office would exceed the maximum value recommended by the WHO guidelines, which is not to exceed 50 μg / m3 for more than 35 days per year.