Table 4. Effect of diesel exhaust exposure, or perception of diesel exhaust exposure, on symptom or symptom cluster.

	Diesel Effect			Perception Effect
Symptom (Cluster)	Positive	OR	Woolf	Positive	OR	Woolf
Any Chest Symptom	27	1.7	0.58	12	27.5	0.06
Any Nose Symptom	50	1.3	0.64	28	4.7	0.03
Any Eye Symptom	43	1.5	0.48	25	3.6	0.13
Headache, Fatigue or Nausea	70	1.4	0.55	41	3.4	0.06

Positive = number of sessions, amongst column total, in which symptoms were reported as present

OR = differential odds-ratio: the ratio between the odds-ratio post-exposure and the odds-ratio pre- exposure (each of these odds-ratio measuring odds of given symptom cluster for DE exposure relative to FA exposure, or [for “perception effect”] for perceived DE exposure relative to perceived FA exposure). Note: for calculating the odds-ratio, 0.5 was added to each cell count, in order to avoid division by zero.

Woolf = the asymptotic Chi-Squared p-value reported by the Woolf test.