Table 2. Comparison of tobacco use on beaches by groups (intervention and comparison), before and after the intervention; smoke-free beaches project (Barcelona, 2021).

		Pre-intervention% (N)	Post-intervention% (N)	Difference(Post−Pre) %	PR(95% CI)
People witnessing smoking on the beach in the last fortnight	Comparison	86.2 (354)	74.1 (1669)	−12.1	1
	Intervention	87.2 (265)	49.7 (1447)	−37.5	0.7 (0.6 to 0.8)*
	P value†	0.91	<0.001
People observed smoking on the beach by the observation team	Comparison	2.3 (388)	9.9 (4008)	7.6	1
	Intervention	3.8 (266)	3 (2542)	−0.8	0.3 (0.3 to 0.4)‡
	P value†	0.28	<0.001

^*Robust Poisson regression with pre-post interaction adjusted by age, gender, smoking status, place of residence and socioeconomic level of Barcelona neighbourhood.

^†P value χ2.

^‡Crude robust Poisson regression.

PRprevalence ratio