This study investigated the spatial distribution and toxicity potential of gaseous criteria air pollutants in the ambient air around a typical haulage truck stop. ToxiRAE II Gas Monitors were used to monitor ambient concentrations of the criteria pollutants both for dry season and wet season. Five sampling points were considered, and a control sampling point was set at about 55 km away from the influence of activities of the truck stop. The results showed the dry season average 24-h concentrations of NO 2 with the range of 0.064-0.335 ppm while CO ranged between 0.919 and 4.911 ppm. During the wet season, the average concentrations of NO 2 ranged between 0.003 and 0.052 ppm, while CO concentration ranged between 0.000 and 4.798 ppm. The result showed average concentration of CO at all sampling points for both dry and wet season was below the Nigerian Federal Ministry of Environment (FEPA) national air quality standard of 10 ppm. However, average concentration of NO 2 at all sampling points during the dry season were above FEPA and World Bank air quality standards except sampling point D. The results also showed the toxicity potential which exceeded unity at some of the designated sampling points is of major concern especially among people with respiratory or heart disease. The study showed the haulage truck stop contributes greatly to the ambient gaseous criteria air pollutants.

Chemical characterization of Portland limestone cement products collected across the nine existing cement manufacturing plants in Nigeria was conducted using Energy Dispersive X-ray Fluorescence Spectrometer (EDXRF) with the aim of determining conformity with global and local standards and investigating likely variation in quality resulting from differences in the sources of major raw materials, especially limestone used in production. The cement samples are composed essentially of CaO, SiO2, Al2O3, Fe2O3, MgO, Na2O, K2O and SO3 while P2O5, MnO and TiO2 were present in trace amount. In addition to oxide compositions, the mineralogical components: Alite (C3S), Belite (C2S), Celite (C3A), and Ferrite (C4AF), and other cement quality control variables such as Lime Saturation Factor, Silica Modulus and Alumina Modulus of all the nine cement samples analyzed in this study are in agreement with the specifications for Portland limestone cement published by the Standard Organisation of Nigeria (SON), the American Society for Testing and Materials (ASTM), and the British Standards Institution (BSI). The nine cement products also have their compositions in close proportion indicating none of the products is superior in quality irrespective of manufacturer or production site, a common misconception in the Nigerian cement market.

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