Environmental characteristics and physical activity: A cross-sectional study in Bulgaria's five largest cities

Urban characteristics can shape physical activity, but evidence regarding their joint role alongside individual perceptions remains limited. This study examined the combined associations of multiple environmental characteristics with physical activity across the five most populous cities in Bulgaria. A cross-sectional survey of 4640 adults was conducted in 2023. Physical activity across different intensity levels was measured with the short form of the International Physical Activity Questionnaire and linked to objective measures of neighborhood walkability, fine particulate matter, road traffic noise, area-level socioeconomic status (SES), and availability of greenspace and bluespace within 300 m and 1000 m buffers. Presence of a home garden was self-reported, along with perceived walkability, bikeability, greenspace, bluespace, and sociodemographic factors. Results showed that walkability, greenspace, area-level SES, home gardens, perceived bluespace, high/low perceived greenspace (vs. medium), and bikeability were positively associated with time spent in vigorous physical activity. Walkability, greenspace, perceived bluespace, low/high perceived greenspace, home gardens, and bluespace were positively associated with moderate-to-vigorous physical activity. Objective and perceived walkability, medium/high levels of greenspace, low/high area-level SES, and home gardens were positively associated with walking. Associations remained robust after accounting for air pollution and noise, which were unexpectedly positively associated with certain forms of physical activity. These findings appear meaningful from a preventive perspective and may provide arguments for improving urban design conducive to physical activity and urban planning initiatives.