Model Prediction of Pollution Standard Index for Carbon Monoxide: A Tool for Environmental Impact Assessment

A model for predicting pollution standard index (PSI) for Carbon monoxide is presented. The model is dependent on 8-hour mean traffic volume, wind speed and solar radiation. Field measurements of CO were carried out at two hour intervals for 5 days. The method adopted for developing the model involved sorting the field observations into 8-hour means and using the Excel (Microsoft office, 2015, regression tool) for development and calibration. Results show that the model yielded a goodness of fit, GF (R2) of 0.939 and when verified the model gave a GFof 0.834. Field observations show good/moderate PSI values for CO concentrations in the afternoon hours when the solar radiation was above 150 W/m2 and wind speed above 2m/s. It also showed unhealthy PSI values for CO concentrations in the evening/night hours when solar radiation falls below 150 W/m2 and wind speed below 2m/s. Design tables were developed from combining the developed model and Pasquil generated table for atmospheric stability. These tables were used to plan Choba junction and results showed that 700 vehicles per hour (8 hour mean) is a safe traffic volume that can operate in Choba junction without negatively impacting the environment. To achieve this we recommend that two bypasses should be created. One bypass should be for the travelers who are leaving town and the other for the UNIPORT staff who operate from Abuja campus. It is strongly recommended that the Federal Ministry of Environment adopts these developed tables as a compulsory tool for planning environmentally safe junctions in Nigeria.