Environmental and Neighborhood Determinants of Psoriasis: A Systematic Review of Pollution, Built Environment, and Socioeconomic Vulnerability on Psoriasis.

Psoriasis is a chronic, immune-mediated skin disease with well-studied genetic and immunologic drivers. Substantial unexplained variability remains, however, in disease onset, severity, and treatment response. There is evidence that implicates the role of environmental and social determinants in these observed differences in psoriasis. We conducted a systematic review to synthesize the current evidence examining the relationship between external exposures, including air and chemical pollution, the built environment, and neighborhood characteristics, and their impact on psoriasis incidence, severity, and exacerbation. Our search in PubMed and Embase (on August 8, 2025 and October 15, 2025, respectively) identified 26 eligible studies. These included nine cohort studies, four ecological studies, and 12 case-control studies. Papers that assessed exposures of ambient air pollutants, chemical pollutants, neighborhood, built environment, income, education, and insurance status were included. The risk of bias for each study was evaluated using the Critical Appraisal Skills Programme (CASP) criteria. Across diverse patient populations and study designs, higher exposure to air pollutants, such as particulate matter and nitrogen oxides, and chemical pollutants, including per- and polyfluoroalkyl substances (PFAS), was associated with increased disease incidence and severity. These were found to contribute to an independently increased risk of psoriasis, even among individuals with a genetic susceptibility to the disease. Climate change associated events, such as wildfires, were linked to increased healthcare utilization for psoriasis. Deleterious neighborhood-level exposures and poor social determinants were also associated with greater psoriasis incidence and exacerbation. Our analysis of existing limitations highlights the need for longitudinal and mechanistic studies to elucidate these relationships, and for the development of standardized definitions for environmental exposures. These findings support a framework for psoriasis that considers environmental and social determinants alongside genetic contributors. Addressing these risk factors requires broader public health initiatives that mitigate exposure and expand healthcare access to at-risk communities.