| Daily PM2.5 levels (μg/m3) | County | |||||
| Los Angeles | Orange | Riverside | San Bernardino | San Diego | Ventura | |
| Before fires | ||||||
| Dates | 01/10–23/10 | 01/10–23/10 | 01/10–20/10 | 01/10–20/10 | 01/10–24/10 | 01/10–22/10 |
| Concentration (SD) | 27.2 (12.4) | 23.3 (9.6) | 32.7 (14.7) | 35.7 (16.6) | 18.5 (6.7) | 18.4 (8.3) |
| During fires | ||||||
| Dates | 24/10–29/10 | 24/10–28/10 | 21/10–29/10 | 21/10–30/10 | 25/10–30/10 | 23/10–30/10 |
| Concentration (SD) | 54.1 (21) | 64.3 (26.5) | 42.1 (25.5) | 45.3 (28.7) | 76.1 (66.6) | 50.1 (50.5) |
| After fires | ||||||
| Dates | 30/10–15/11 | 29/10–15/11 | 30/10–15/11 | 31/10–15/11 | 31/10–15/11 | 31/10–15/11 |
| Concentration (SD) | 15.9 (5.5) | 15.5 (10.2) | 16.9 (8.6) | 18.4 (8.3) | 14.2 (7.2) | 12.9 (4.3) |
*PM2.5 concentrations are calculated with equal weighting per zip code.