Health burden and inequities of urban environmental stressors in Sofia, Bulgaria

Background

The number of studies on the health impacts of urban environmental stressors has been growing. However, research for South-Eastern Europe remains limited. We conducted a baseline Health Impact Assessment for Sofia, Bulgaria, focusing on air pollution, green space, road-traffic noise, and urban heat island (UHI) exposure aiming to promote discussions on sustainable, health-centric urban and transport planning policies.

Methods

The analysis was conducted at the neighbourhood level (n = 4969). The study population included 1,168,382 inhabitants, considering adults and children. Data were retrieved from Europe-wide and local exposure models, local censuses and surveys. We used comparative risk assessment methodology, comparing baseline with optimal scenarios for health, such as meeting World Health Organization (WHO) air quality and road-traffic noise guidelines, green space recommendations, and no UHI effect. We also examined exposure and health impact distributions by area-level socioeconomic status (SES). We approximated differences in baseline disease rates by SES using data from local surveys. The results were stratified by SES quartiles and analysed spatially using global and local bivariate Moran's I statistics, the latter to identify priority areas for intervention based on SES, environmental exposures, and health outcomes.

Results

All Sofia residents lived in neighbourhoods where particulate matter with diameter ≤2.5 μm (PM2.5) and nitrogen dioxide (NO2) levels exceeded the WHO air quality guidelines, with mean noise levels of 62.2 dB(A) Lday, 77 % lacking sufficient availability of green space, and an average summer UHI of 2.5 °C. The largest mortality burden was from PM2.5 exposure (1939 annual deaths (95 % CI: 1349–2571)), followed by NO2 (1172 annual deaths (444-2027)), road-traffic noise (902 annual deaths (556-1311)), insufficient green space (217 annual deaths (169–262)), and UHI (95 summer deaths (58–130)). PM2.5 contributed to 17–21 % of cardiovascular disease cases, while noise accounted for 5 % of Ischaemic Heart Disease and stroke cases. NO2, noise, and UHI exposures tended to be higher in higher SES areas, while PM2.5 tended to be lower. Spatial analysis revealed that central areas, with high-SES populations, and northern, north-eastern, and north-western areas, with lower-SES populations, all experience high exposure and health impacts.

Conclusions

The analysis showed a significant health burden from urban environmental stressors in Sofia, with an uneven distribution across SES groups. Health-promoting policy interventions should consider both environmental and socioeconomic factors to prioritize areas for action.