I am sure that the publication of Effiong Ukorebi ETIM in February 2012, in African Journal of Environmental Science and Technology Vol. 6(2): 125-129. will suffice. The title is on Estimation of pollution load from an industrial estate, south-western Nigeria.
Just to know, sometimes you also develop the kind of index you want for your study. It actually would depend on what you think would amount to possible hazard especially when compared to statutory benchmarks
Pollution load or environmental load of a pollutant is dependent on the source of pollution. For eg. if you are interested in calculating the pollution load from coal power plants in a district, then first identify all such power plants, then calculate or obtain the emission rate (generally available in microgram per cubic meter) for each source. Convert this to Kg/Km3. Combine all sources for the net pollution load from all such industries in Kg/Km3. The pollution load is generally required to deduce the supportive capacity of the environment.
The total load is calculated as the sum of the daily loads that are obtained by multiplying the measured or estimated daily concentration by the total daily discharge.
The best way to estimate the pollution on global or synoptic scale is by using the satellites data and imagery. In this context, there are two important variables: concentration and optical air mass.