Abstract: Study objective: The objective of this study is to demonstrate the methodological shortcomings of currently available analytical methods for single-city time series data, one of the most commonly used ecological study designs in air pollution and respiratory disease research. Design and Methods: We analyse single city epidemiological time series of daily Chronic Obstructive Pulmonary Disease (COPD) (ICD codes 490-492, 494, 496) and daily asthma (ICD codes 493) hospital admissions in Melbourne, Australia from July 1989 to December …