Self-reported symptoms with onset after beginning current job*
| Conventional asphalt workers | CRM asphalt workers | All asphalt workers | Controls | P values† | P values‡ | |
| (no/yes, %) | (no/yes, %) | (no/yes, %) | (no/yes, %) | |||
| Wheezing | 84/12 (13) | 33/3 (8) | 117/15 (11) | 70/3 (4) | 0.15 | 0.12 |
| Shortness of breath | 94/2 (2) | 35/1 (3) | 129/3 (2) | 71/2 (3) | 0.99 | 0.99 |
| Cough | 80/16 (17) | 32/4 (11) | 112/20 (15) | 68/5 (7) | 0.19 | 0.12 |
| Eye symptoms (redness/secretion/swelling) | 72/24 (25) | 29/7 (19) | 101/31 (23) | 66/7 (10) | 0.029 | 0.014 |
| Nasal symptoms (runny nose/nasal congestion/sneezing) | 70/26 (27) | 29/7 (19) | 99/33 (25) | 59/14 (19) | 0.46 | 0.39 |
| Nasal bleeding | 88/8 (8) | 34/2 (6) | 122/10 (8) | 65/8 (11) | 0.68 | 0.44 |
*Defined as a negative response to the question ‘Did you have the symptom before you began working in your current job?’ on the off-season questionnaire, to which 96 conventional asphalt workers, 36 CRM asphalt workers and 73 controls responded.
†P values were derived from χ2 test or Fisher’s exact test by comparing three occupational groups.
‡P values from χ2 test or Fisher’s exact test by comparing between all asphalt workers and controls.