Effect of cement production processes on dry atmospheric chemistry in South-South Nigeria

Abstract Cement industries contribute significantly to poor air quality globally. As cement production expands in Nigeria, so too does its environmental footprint. Despite the well-documented dangers of cement-related air pollution, there is a lack of comprehensive scientific evidence-based studies on monthly variations of air quality around cement plants in Southern Nigeria. There is a pertinent need for a systematic investigation into how cement production affects dry atmospheric chemistry and contributes to environmental degradation in the region; hence, the study evaluated the effect of cement production processes on ambient atmospheric chemistry at the Lafarge Holcim cement processing plant in Cross River, Southern Nigeria. Using mobile real-time air quality monitors (MX IBRID) , levels of carbon monoxide (CO), carbon dioxide (CO2), sulphur dioxide (SO2), nitrogen dioxide (NO2), volatile organic compound (VOC), hydrogen sulphide (H2S) and particulate matter (PM2.5, PM10) were taken from cement production sites: milling site, quarrying site and loading bay for a 12-month period (January to December, 2023). The results revealed that the milling site had the highest relative levels of dry atmospheric chemistry (NO2; 0.15 ± 0.01 ppm, SO2; 5.78 ± 0.008 ppm, VOCs; 8.41 ± 0.13 ppm, CO; 575.5 ± 722.5 ppm, PM10; 346.2 ± 128.4 μg/m3), and the quarrying site had the highest PM2.5 (31.6 ± 0.04 μg/m3). Comparison with different global standards showed significant exceedances in CO, SO2 and NO2, PM10 across the three sites with more than 35% increase relatively. The correlation matrix revealed a significant relationship among and between pollutants and meteorological parameters. Principal component analysis showed high positive and negative loadings of CO, CO2, SO2, NO2, VOC, H2S, PM2.5 and PM10 existing in clusters from different sources. The monthly air quality index report implicated PM10 and SO2 as major constituents of hazardous and very unhealthy air quality around the area. Key recommendations were made, among others, that the company must regularly conduct an environmental audit of all their processes so as to improve their environmental performance, adopt pollution reduction technologies such as the use of water spray, gas scrubbers, filters and alternative sources of fuel such as solar power. Environmental regulators must also brace up and issue sanctions, set restrictions and issue heavy fines when there is a breach of environmental responsibilities on the part of the company.