Table 2.
Ratios of pollutant concentration measured in a street canyon to that in a corresponding background location; climate classification is made according to Köppen–Geiger Climate Classification System [52]; PAHs is the abbreviation of polycyclic aromatic hydrocarbons, while Cr, Cu and Fe for chromium, copper and iron, respectively.
| City/climate | Measurement period | PM10 | PM10–2.5 | PM2.5 | BC | Cr, Cu and Fe | NOx | NO2 | NO | CO | VOCs | PAHs | Benzene | Reference |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Guangzhou/Warm temperate (Cwa) | Feb. 1–2, 2002 | 1.2 | – | – | – | – | – | – | – | 4.7 | – | – | 1.4 | [86] |
| Hong Kong/Warm temperate (Cwa) | Jan. 1 – Dec. 8, 2005 | – | 1.3 | 1.5 | – | – | – | – | – | – | – | – | – | [102] |
| 5 Dutch cities/Maritime temperate (Cfb) | 6-month beginning in Jun. 2008 | 1.2 | – | 1.2 | 1.9 | 2.0–3.0 | 1.8 | 1.5 | – | – | – | – | – | [31], [109] |
| Copenhagen/Maritime temperate (Cfb) | Jan.–Mar. 1992–1994 | – | – | – | 2.4 | – | – | – | – | – | – | 3.2–5.3 | – | [110] |
| Raleigh/Warm temperate (Cfa) | Aug. 11 – Sep. 20, 1988 | – | – | – | – | – | – | – | – | – | 1.7 | – | – | [111] |
| Los Angeles/Dry-summer (Csa) | Feb. 14, 20, Apr. 7, 16, 24, 2003 | – | – | – | – | – | – | 2.0 | 13.9 | 2.6 | – | – | – | [99] |