(1) Background: Exposure to environmental tobacco smoke has decreased in recent years in Spain, due to the implementation of tobacco control policies. However, there is no regulation that protects against second-hand smoke (SHS) in outdoor environments. Our goal is to describe the smoking prohibition signage in public spaces and to characterize tobacco consumption in outdoor environments describing the SHS exposure in children. (2) Methods: A cross-sectional study using direct observation was carried out with a convenience sample (n = 179) that included hospitality venues with terraces, schools and healthcare facilities in the municipality of Sant Cugat del Vallès (Barcelona, Spain). The observations were made without notifying the owners by one single field researcher between April and June 2018. The variables were evaluated by signage and signs of tobacco consumption (ashtrays, cigarette butts and presence of smokers). (3) Results: Smoke-free zone signage outside public spaces was present in 30.7% of all venues, with only 50.9% correctness. When analysing terraces of hospitality venues, in 35.8% of them there were children present with 66.7% of tobacco consumption. (4) Conclusions: Our results show a low prevalence of antismoking signage, without an impact on tobacco consumption regardless of the presence of children.