There is limited research on indoor air quality in the Middle East. In this study, concentrations and size distributions of indoor particles were measured in eight Jordanian dwellings during the winter and summer. Supplemental measurements of selected gaseous pollutants were also conducted. Indoor cooking, heating via the combustion of natural gas and kerosene, and tobacco/shisha smoking were associated with significant increases in the concentrations of ultrafine, fine, and coarse particles. Particle number (PN) and particle mass (PM) size distributions varied with the different indoor emission sources and among the eight dwellings. Natural gas cooking and natural gas or kerosene heaters were associated with PN concentrations on the order of 100,000 to 400,000 cm −3 and PM 2.5 concentrations often in the range of 10 to 150 µg/m 3 . Tobacco and shisha (waterpipe or hookah) smoking, the latter of which is common in Jordan, were found to be strong emitters of indoor ultrafine and fine particles in the dwellings. Non-combustion cooking activities emitted comparably less PN and PM 2.5 . Indoor cooking and combustion processes were also found to increase concentrations of carbon monoxide, nitrogen dioxide, and volatile organic compounds. In general, concentrations of indoor particles were lower during the summer compared to the winter. In the absence of indoor activities, indoor PN and PM 2.5 concentrations were generally below 10,000 cm −3 and 30 µg/m 3 , respectively. Collectively, the results suggest that Jordanian indoor environments can be heavily polluted when compared to the surrounding outdoor atmosphere primarily due to the ubiquity of indoor combustion associated with cooking, heating, and smoking.
The main objective of this study was to investigate the accumulation and coarse particles concentration inside an educational workshop and calculate emissions factors as well inhaled deposited dose. We measured the particle number distribution (diameter 0.3-10 µm) and focused on two particle size fractions: submicron particles in the diameter range 0.3-1 µm and coarse particles (1-10 µm). The occupants activities inside the workshop included coffee brewing, lecturing, tobacco smoking, welding, scrubbing, and sorting/drilling iron. The highest concentrations were observed during welding activities; mean PN0.3-1 (PM0.3-1) and PN1-10 (PM1-10) concentrations were about 1865.86 (54.49 μg/m 3 ) and 6.46 cm -3 (102.54 μg/m 3 ) with most of the particles were emitted below 1 μm in diameter. The alveolar received the majority and particles below 1 µm with a fraction of about 53% of the total inhaled deposited dose whereas the head/throat region received about 18%.
Objective:
Dry deposition velocity towards a surface is commonly investigated by modelling. However, there is still a lack of understanding about the nature of the concentration boundary layer (CBL).
Methods:
We aimed at acquiring in-depth description of the particle concentration profile within the CBL by investigating the layer height and the concentration profile. The particle concentration, as a solution to the particle flux equation, is obtained and modeled numerically by performing left Riemann sum using MATLAB software. The friction velocity u^* and the particle diameter D_p are the major parameters taken into consideration when characterizing the concentration boundary layer above a surface. The particle concentration profile depends on the friction velocity; the concentration gradient starts from zero at the surface and reaches its maximum in the middle of the layer and then reaches zero again at the top of the boundary layer
Results:
The concentration profile is slightly altered with a sudden increase in the concentration gradient at the surface when considering large particles or when the friction velocity is has extreme values.
Conclusion:
The boundary layer height (y+cbl) varied with the particle diameter, and a proper value is 100 to ensure accurate calculations for the dry deposition velocity (diameter 0.01 – 100 µm) above a smooth surface. From a numerical point of view, the numerical setup of the calculation required y+ divisions to be more than 1000 for all particle diameters included in the investigation. In addition, y+max = 104 is important for ultrafine particles (diameter smaller than 0.1 µm). Nevertheless, y+max does not need to be investigated beyond 100 when the friction velocity is below 10 cm/s.
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