Regarding spatial trends, whilst seasonality of certain diseases will influence AA usage, fluctuating populations will also play a role here. Bath will have population fluctuations due to tourism and an active student population (equating to an estimated 7,250 and 5,800, respectively, additional to the calculated resident PE (table )). Whilst university students will typically be away over summer months (June-September), this is considered peak season for tourism. It is estimated that populations fluctuations in Bath will be around ±20%. Considering the high uncertainties associated with wastewater sampling, it is unlikely the effects of a variable population at this scale will have a visible and notable impact upon AA levels.