Determination of rare earth elements in dust deposited on tree leaves from Greater Cairo using inductively coupled plasma mass spectrometry.

This work aims at monitoring the rare earth elements (REEs) and Th in dust deposited on tree leaves collected inside and outside Greater Cairo (GC), Egypt. Inductively coupled plasma mass spectrometry (ICP-MS) was employed. The concentration of REEs in the collected dust samples was found to be in the range from 1 to 60 µg g(-1). The highest concentration of REEs was found in dust samples collected outside GC, in the middle of the Nile Delta. This would refer to the availability of black sands, due to desert wind occurrence during the sample collection, and anthropogenic activities. The limits of detection of the REEs ranged from 0.02 ng g(-1) for Tm to 3 ng g(-1) for Yb. There was an obvious variation in the concentration of REEs inside and outside GC due to variations of natural and anthropogenic sources. Strong correlations among all the REEs were found.

Gas-particle concentration, distribution, and health risk assessment of polycyclic aromatic hydrocarbons at a traffic area of Giza, Egypt.

Atmospheric particulate and gaseous polycyclic aromatic hydrocarbons (PAHs) samples were collected from an urban area in Dokki (Giza) during the summer of 2007 and the winter of 2007-2008. The average concentrations of PAHs were 1,429.74 ng/m(3) in the particulate phase, 2,912.56 ng/m(3) in the gaseous phase, and 4,342.30 ng/m(3) in the particulate + gaseous phases during the period of study. Dokki has high level concentrations of PAH compounds compared with many polluted cities in the world. The concentrations of PAH compounds in the particulate and gaseous phases were higher in the winter and lower in the summer. Total concentrations of PAHs in the particulate phase and gaseous phase were 22.58% and 77.42% in summer and 36.97% and 63.03% in winter of the total (particulate + gaseous) concentrations of PAHs, respectively. The gaseous/particulate ratios of PAHs concentration were 3.43 in summer and 1.71 in winter. Significant negative correlation coefficients were found between the ambient temperature and concentrations of the total PAHs in the particulate and gaseous phases. The distribution of individual PAHs and different categories of PAHs based on aromatic ring number in the particulate and gaseous phases during the summer and winter were nearly similar, indicating similar emission sources of PAHs in both two seasons. Benzo(b)fluoranthene in the particulate phase and naphthalene in the gaseous phase were the most abundant compounds. Diagnostic concentration ratios of PAH compounds indicate that these compounds are emitted mainly from pyrogenic sources, mainly local vehicular exhaust emissions. Health risks associated with the inhalation of individual PAHs in particulate and gaseous phases were assessed on the basis of its benzo(a)pyrene equivalent concentration. Dibenzo(a,h)anthracene and benzo(a)pyrene in the particulate phase and benzo(a)pyrene and benzo(a)anthracene in the gaseous phase were the greatest contributors to the total health risks. The relative mean contributions of the total carcinogenic activity (concentrations) of all PAHs to the total concentrations of PAHs were 29.37% and 25.15% in the particulate phase and 0.76% and 0.92% in the gaseous phase during the summer and winter, respectively. These results suggest that PAHs in the particulate phase in the ambient air of Dokki may pose a potential health risk.

Study on some factors affecting survivability of airborne fungi.

The aim of the present study was to investigate the effect of some air pollutants and meteorological parameters on the survivability of airborne fungi. Fungi were collected by using a slit impactor sampler calibrated to draw 20 L/min, for 3 min. Nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), particulate matter (PM), relative humidity (RH %), temperature (T °C) and wind speed (WS) were also measured. Air samples were taken during the period from March 2006 to February 2007. Fungal concentrations ranged between 45 and 451 CFU/m(3) with an annual mean concentration of 216 CFU/m(3). The lowest fungal concentration was found in the summer, however the highest one was found in the autumn. NO(2,) SO(2) and PM averaged 83.66 µg/m(3), 67.01 µg/m(3), and 237.69 µg/m(3), respectively. T °C was positively and negatively correlated with Aspergillus (P = 0.000) and Penicillium (P = 0.007), respectively. RH% was positively correlated with total fungi (P = 0.001), Aspergillus (P = 0.002) and Cladosporium (P = 0.047). Multiple regression analysis showed that T °C and RH% were the most predicted variants. Non-significant correlations were found between fungal concentrations and air pollutants. Meteorological parameters were the critical factors affecting fungal survivability.

Diurnal distribution of airborne bacteria and fungi in the atmosphere of Helwan area, Egypt.

Airborne bacterial and fungal composition in an industrial town of Helwan, Egypt, was studied using a slit impactor sampler during the period from March 2006 to February 2007. Airborne bacterial concentrations were usually higher than fungi. Bacteria and fungi had similar diurnal variation patterns. Airborne microorganisms reached their concentration peaks in the evening and gradually decreased during the night time. The hourly concentration peaks of the bacteria and fungi appeared at 20:00h. A significant difference (P < or =0.05) was found between the hourly mean concentrations of airborne fungi in winter compared to other seasons. Fungi concentrations were significantly higher (P< or =0.05) on working weekdays than weekends. Aspergillus, Penicillium, Alternaria and Cladosporium were the most predominant airborne fungal genera. Aspergillus showed double peak patterns whereas Penicillium, Alternaria and Cladosporium showed one peak pattern. The diurnal variations of the bacteria and fungi could be divided into four periods: 1) the morning maximum concentration (6:00h-10:00h), 2) midday to afternoon pattern (10:00h-16:00h), 3) the evening concentration peak (18:00h-20:00h) and 4) the gradual decrease of night time concentration (22:00h-24:00h). Geographical location, human activity, growth cycle of organisms and meteorological factors were the main criteria controlling the temporal variations of the air microorganisms in the Wadi Hof area.

Diurnal, seasonal and weekdays-weekends variations of ground level ozone concentrations in an urban area in greater Cairo.

Ground level ozone (O3) concentration was monitored during the period of December 2004 to November 2005 in an urban area in Greater Cairo (Haram, Giza). During the winter and summer seasons, nitrogen dioxide (NO2) and nitric oxide(NO) concentrations and meteorological parameters were also measured. The mean values of O3 were 43.89, 65.30, 91.30 and 58.10 ppb in daytime and 29.69, 47.80, 64.00 and 42.70 ppb in whole day (daily) during the winter, spring, summer and autumn seasons, respectively. The diurnal cycles of O3 concentrations during the four seasons revealed a uni-modal peak in the mid-day time, with highest O3 levels in summer due to the local photochemical production. The diurnal variations in NO and NO2 concentrations during the winter and summer showed two daily peaks linked to traffic density. The highest levels of NOx were found in winter. Nearly, 75%, 100%, 34.78% and 52.63% of the mean daytime concentrations of O3 during spring,summer, autumn and the whole year, respectively, exceeded the Egyptian and European Union air quality standards (60 ppb) for daytime (8-h) O3 concentration. About, 41.14% and 10.39% of the daytime hours concentrations and 14.93% and 3.77% of the daily hour concentrations in summer and the whole year, respectively, exceeded the Egyptian standard (100 ppb) for maximum hourly O3 concentration, and photochemical smog is formed in the study area (Haram) during a periods represented by the same percentages. This was based on the fact that photochemical smog usually occurs when O3 concentration exceeds 100 ppb. The concentrations of O3 precursors (NO and NO2) in weekends were lower than those found in weekdays, whereas the O3 levels during the weekends were high compared with weekdays. This finding phenomenon is known as the "weekend effect". Significant positive correlation coefficients were found between O3 and temperature in both seasons and between O3 and relative humidity in summer season, indicating that high temperature and high relative humidity besides the intense solar radiation (in summer) are responsible for the formation of high O3 concentrations.

Atmospheric conversion of sulfur dioxide to particulate sulfate and nitrogen dioxide to particulate nitrate and gaseous nitric acid in an urban area.

Sulfur dioxide, nitrogen dioxide, particulate sulfate and nitrate, gaseous nitric acid, ozone and meteorological parameters (temperature and relative humidity) were measured during the winter season (1999-2000) and summer season (2000) in an urban area (Dokki, Giza, Egypt). The average particulate nitrate concentrations were 6.20 and 9.80 microg m(-3), while the average gaseous nitric acid concentrations were 1.14 and 6.70 microg m(-3) in the winter and summer seasons, respectively. The average sulfate concentrations were 15.32 microg m(-3) during the winter and 25.10 microg m(-3) during the summer season. The highest average concentration ratio of gaseous nitric acid to total nitrate was found during the summer season. Particulate sulfate and nitrate and gaseous nitric acid concentrations were relatively higher in the daytime than those in the nighttime. Sulfur conversion ratio (Fs) and nitrogen conversion ratio (Fn) defined in the text were calculated from the field measurement data. Sulfur conversion ratio (Fs) and nitrogen conversion ratio (Fn) in the summer were about 2.22 and 2.97 times higher than those in the winter season, respectively. Moreover, sulfur conversion ratio (Fs) and nitrogen conversion ratio (Fn) were higher in the daytime than those in the nighttime during the both seasons. The sulfur conversion ratio (Fs) increases with increasing ozone concentration and relative humidity. This indicates that the droplet phase reactions and gas phase reactions are important for the oxidation of SO2 to sulfate. Moreover, the nitrogen conversion ratio (Fn) increases with increasing ozone concentration, and the gas phase reactions are important and predominant for the oxidation of NO2 to nitrate.

Nitrous acid concentrations in homes and offices in residential areas in Greater Cairo.

Indoor and outdoor measurements of nitrous acid and nitrogen dioxide were conducted at four homes and two offices in residential areas in Greater Cairo during winter (2000-2001) and summer (2001) seasons. Indoor nitrogen dioxide concentrations were higher than outdoor levels at the four homes, whereas indoor concentrations of nitrogen dioxide were lower than outdoor levels at the two offices, during both seasons. Indoor nitrous acid concentrations were higher than outdoor levels at all homes and offices during the period of study. The mean indoor nitrous acid concentrations were 6.8 ppb and 3.67 ppb in the four homes, whereas they were 1.42 ppb and 1.24 ppb in the two offices, during the winter and summer seasons, respectively. Indoor/outdoor ratios of nitrous acid concentration were 6.94 in the winter and 5.03 in the summer for all of the homes. However, the ratios were 1.31 and 1.61 during the winter and summer seasons, respectively, for the two offices. Insignificant positive correlation coefficients were found between indoor and outdoor concentrations of nitrous acid at homes and offices. The maximum outdoor nitrous acid concentrations were recorded during the winter season. Significant positive correlation coefficients were found between nitrous acid and nitrogen dioxide and relative humidity in homes and offices. The ratios of nitrous acid to nitrogen dioxide concentrations ranged from 0.045 to 0.16, with a mean of 0.1, in the four homes, whereas the ratios ranged from 0.026 to 0.09, with a mean of 0.059, in the two offices.

Organic dust and gaseous contaminants at wood working shops.

Airborne dust bioaerosols, ammonia and formaldehyde levels were determined inside two different (ventilated and unventilated) wood working shops. Airborne dust was found at mean values of 4.3 and 3.01 mg m(-3). These levels were higher than that recommended by Egyptian environmental law [1 mg m(-3) indoor maximum allowable concentration (MAC) for hard wood]. The highest frequency of aerodynamic size distribution of airborne wood dust was detected at a diametre of 4.9 microm which was recorded during a machining operation. Total viable bacteria were recorded at a mean value of 10(4) colony-forming units (cfu) m(-3), whereas Gram-negative bacteria were found at very low counts (10(1) cfu m(-3)). Fungi levels were recorded at mean values of 10(3) and 10(2) cfu m(-3) in ventilated and unventilated shops, respectively. Penicillium, Aspergillus, Cladosporium and yeast species were dominant isolates. Moreover, actinomycetes were found at a mean value of 10(3) cfu m(-3) at both workshops. Ammonia was detected in relatively low concentrations (mean values of 457 and 623 microg m(-3)), whereas formaldehyde was found in relatively moderate concentrations (mean values of 0.42 and 0.64 ppm).

Evaluation of airborne lead in the welding working environment.

Manual and automatic welding machines (which use leaded alloys) are considered to be important sources of the emission of lead fumes into the general air of the working environment. Three workplaces at a television factory were selected for the present study, to determine the control class of the working unit. The concentrations of conventional measurements ("A" sampling points) were lower than the administrative control level (statutory standard of lead, 150 microg m(-3)), whereas the maximum concentration of 264.1 microg m(-3) ("B" sampling point) was higher at one working unit than the administrative control level. However, the control classes varied between class III (bad) and class I (good).

Indoor and outdoor formaldehyde concentrations in homes in residential areas in Greater Cairo.

Indoor and outdoor measurements of formaldehyde were conducted at seven flats located in residential areas in Greater Cairo, during spring and summer seasons 1999. The mean daytime formaldehyde concentrations in kitchens, bedrooms and living rooms were 89, 100 and 100 ppb, respectively, in the seven flats. Significant positive correlations were found between the concentrations of formaldehyde found in these three rooms. On the other hand, no significant differences were found between the mean formaldehyde concentrations in these three rooms. The maximum mean concentration of formaldehyde (147 ppb) was recorded in a new flat, while the minimum concentration (43 ppb) was observed in an old flat. The maximum hourly and daytime concentrations were 350 and 225 ppb, respectively. Air temperature, relative humidity and the age of the flat are factors affecting the emission and concentration of formaldehyde. The maximum indoor and outdoor formaldehyde concentrations were recorded during the summer season. During the spring, 38% of the samples indicated that the concentration of formaldehyde in the seven flats exceeded 0.1 ppm, the American Society of Heating, Refrigerating, and Air Conditioning Engineers' (ASHRAE) standard; in the summer, this figure increased to 53%.