No abstract

Klang Valley, a heavily industrialized urban area in Malaysia, has experienced severe haze episodes since the early 1980s. Total Suspended Particulate matter (TSP) is used in studying this phenomenon. Three severe haze episodes during the early 1990s are reviewed; August 1990, October 1991, and August-October 1994. The nature of these episodes, their possible causes, and their major features are discussed. Meteorological conditions associated with these episodes were analyzed. Results of the study indicate that stability and trapping of particles are the main factors affecting the pollution during haze periods. Maximum total suspended matter (TSP) was recorded in October 1991. The August-October 1994 episode was the most persistent and least affected by meteorological variables. Analysis of wind direction data showed that southerly and southwesterly winds coincided with the worst haze periods.

No abstract

This study quantified the effect of imploding old concrete grain silos in Aqaba, Jordan, on the eastern side of the Gulf of Aqaba, an arid region, on air quality by measuring the PM 10 concentrations before and after the implosion at four monitoring locations. The implosion of the silos forms part of a comprehensive plan to relocate and upgrade the Port of Aqaba, which is situated on the coast of the Red Sea, with the goal of freeing space for development and improving the infrastructure in the heart of the city. The demolition, which occurred at 11:00 a.m. (local time) on 13 January 2019, generated a massive cloud of dust that was transported to nearby areas. To characterize these emissions, descriptive statistics, graphical methods, inverse distance weighting interpolation, decision trees constructed with recursive partitioning, the Gaussian dispersion model, the modified box model, and regression analysis were applied. The PM 10 concentrations were in compliance with the Jordanian 24-h standard of 120 µg m-3 prior to the implosion but substantially increased (although still varied by distance from the demolition site) at all four stations afterward, with the maximum values (259-587 µg m-3) exceeding the pre-implosion ones by as much as 26 times. However, these high concentrations were short-lived, and the majority of the stations returned to background levels within 30-33 hours. According to our calculations on the implosion, the PM 10 emission rate was 17 ± 2 mg m-2 s-1 , which is equivalent to 215 ± 22 kg silo-1 , and the air mixing height was 613 ± 72 m, or approximately eight times the height of the silos.