| Date | PST concentration (mg∙m−3) | |
| Day | Night | |
| 1986 | 18.4 ± 4.6 | 32.1 ± 9.0 |
| September-October, 2002 | 15.6 ± 4.5 | 13.6 ± 4.8 |
| November-December, 2002 | 16.4 ± 4.4 | 19.9 ± 5.0 |
| September-October, 2003 | 23.6 ± 4.6 | 25.7 ± 5.5 |
| May-Jun, 2004 | 34.6 ± 7.0 | 38.9 ± 8.1 |