Objective To describe workplace exposure to secondhand smoke (SHS) among different working populations in Shanghai; to identify any association between respiratory symptoms and SHS exposure in these workplaces.

Design Cross-sectional survey with a standardised questionnaire.

Setting 150 worksites (including restaurants, shopping malls, hotels, hospitals, schools, kindergartens).

Subjects 3530 workers.

Outcome measures Prevalence of workers with workplace exposure to SHS; average time of exposure to SHS per day; proportion of workers reporting any respiratory and sensory symptoms.

Results 13.3% of employees were covered by complete smoke-free policies. Restaurant employees had the highest level of exposure to SHS (67% exposed with 2.95±3.10 h of exposure on average per day) while kindergarten employees had the lowest level (0.5% exposed with 0.01±0.01 h of exposure per day). Compared with employees from kindergartens, non-smoking workers from restaurants and shopping malls reported a higher proportion of respiratory and sensory symptoms and were more likely to suffer from all eight respiratory and sensory symptoms (OR 1.8–8.9). The length of exposure to SHS each day was positively associated with all eight symptoms except runny nose.

Conclusions Workplace exposure to SHS is extensive in Shanghai and the implementation of the current municipal regulation does not provide adequate worker protection. There is an urgent need to establish 100% smoke-free legislation covering all workplaces and public places in Shanghai.