The current investigation examined the relationships between ozone, wind direction and IER parameters in the Illawarra region. Moderate and high ozone concentrations in the region usually occurred under north-east to north-northeast winds. From plots of ozone concentration against time three distinct pattern types were identified, characterised mainly by differences in the rate and timing of increase and subsequent decrease in ozone concentration during the day. Smog produced (SP) and Extent of ozone production (E) both increased with time once winds turned onshore, indicating that aged photochemical smog was being transported into the Illawarra area from source regions to the north. Days with the lowest ozone concentrations were the least reactive and showed the least variability in photochemical reactivity. Conversely, high ozone concentrations were associated with both high reactivity and high variability in levels of reactivity.