Ambient Air Quality Assessment of Orlu, Southeastern, Nigeria

Background and Objective: Ambient air quality assessment of Orlu was carried out with reference to four criteria air pollutants which include particulate matter (PM 10 ), nitrogen dioxide (NO 2 ), sulfur (iv) oxide (SO 2 ) and carbon monoxide (CO).The objective of the study was to determine the atmospheric concentration and to further assess the air quality level of Orlu.Methodology: Five locations were studied within the months of November, 2014-February, 2015 using mobile air quality monitoring devices.The sampling was carried out once a week in each of the five air monitoring locations, 3 times/day (morning, afternoon and evening) and 4 times a month for a period of 3 months.The measured air quality data were analyzed using one way ANOVA (p<0.05) while its spatial distribution was studied using the Box and Whiskers plots.Similarly, the influence of wind speed and wind direction on atmospheric dynamics was assessed with the aid of wind rose diagrams while air quality condition was determined by using air quality index technique (AQI).Results: The result of the study showed that the mean concentration of the air pollutants ranged as follows: PM 10 (3.40-11.53)mg mG 3 , NO 2 (0.20-0.70) ppm, SO 2 (0.17-0.75) ppm and CO (26.00-51.00)ppm.The observed variations of mean levels of the atmospheric pollutants are in the order: Umuna junction>Banana junction>Umuaka>Ogboko junction>Umuago Urualla.The mean level of PM 10 , NO 2 and CO in all the air quality monitoring locations exceeded the US NAAQS (US National Ambient Air Quality Standard) and Nigerian National ambient Air Quality Standards except the NO 2 concentration at Umuago Urualla, while SO 2 level was within Nigerian NAAQS limit but above US NAAQS.ANOVA (p<0.05)analysis revealed no significant difference in the mean concentrations of the measured air pollutants except NO 2 at Banana junction, PM 10 at Umuaka junction and Ogboko junction.Results of the AQI analysis ranged from 151-225 which implies unhealthy and very unhealthy atmosphere.The wind rose diagrams revealed that the wind speed and wind direction contributed significantly to the dispersion and transportation of the atmospheric pollutants.Conclusion: The findings of the present study suggests that anthropogenic activities in the area and environs are responsible for the observed air quality levels.Strict monitoring of the atmospheric conditions of the study area is, therefore, recommended in view of the adverse health implications.