Our Project
The diurnal variation of pollutants such as particles and carbon monoxide (CO) in urban environments typically follow the traffic density, with two peaks coinciding with the weekday morning and evening rush-hour periods. However, KOALA observations in the Brisbane CBD have demonstrated an anomalous diurnal variation with the CO peak in the evening being significantly higher than that in the morning. This imbalance was not observed for particle concentrations.
Here, we show that the imbalance is a direct result of the difference in CO emission factors from motor vehicles during warm and cold starts. Over 30,000 cars with warmed-up engines enter Brisbane city centre car parks every weekday morning. They all start their engines from cold and leave the city in the evening, producing the anomalously higher emissions of CO in the city centre. This pattern of air quality was confirmed with greater certainty by means of two KOALA sensors installed inside an underground car park on the QUT Campus. The figure below shows the contrast between the CO concentrations measured during the morning (AM) when cars with warmed up engines entered the car park, and in the evening (PM) when the same number of cars exited the car park with relatively cold engines. The pattern was not shown by a number of KOALAs located outside the city limits and in the suburbs.
These results were published in the journal Atmospheric Environment and may be found at https://doi.org/10.1016/j.atmosenv.2020.118035 Available online 24 October 2020. 1352-2310/© 2020 Elsevier Ltd. All rights reserved. (see below).
To the best of our knowledge, no previous study has drawn attention to this phenomenon and no explanation has been provided in the literature to-date.
Our Team
Project Leader
- Lidia Morawska, ILAQH, QUT
Investigators
- Rohan Jayaratne, ILAQH, QUT
- Phong Thai, UQ
- Bryce Christensen, ILAQH, QUT
- Xiaoting Liu, ILAQH, QUT
- Isak Zing, ILAQH, QUT
- Matthew Dunbabin, QUT
- Riki Lamont, QUT
- Laura Dawkins, Meteorological Office, Devon (UK)
- Lidwina Bertrand, CIBICI, (Argentina)
