Association between fine particulate matter (PM2.5) and atopic dermatitis—a systematic review

Particulate matter (PM2.5) is associated with numerous adverse outcomes due in part to its ability to enter systemic circulation. Though its impact on the respiratory and cardiovascular systems is well studied, focus is now being placed on additional organ systems that are also associated with significant morbidity. Thus, this systematic review aims to summarize the available data on the association between particulate matter (PM2.5) exposure and atopic dermatitis (AD); and to describe the likely pathophysiological links. A literature search was conducted using PubMed, ScienceDirect, and SCOPUS. Studies on the prevalence or incidence of atopic dermatitis as an outcome, with exposure to particulate matter (PM2.5) as a predictor were included. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The risk of bias in the selected studies was assessed using the QUADAS-2 tool. Eleven studies met the specified inclusion criteria. All found statistical significance of an increase in AD in some subgroups, though not all found significance in the general population. Outcomes measured included the number of visits to clinics and hospitals or changes in AD symptoms to determine if AD was worsened. Males, children, and the elderly were noted in multiple studies as having an increased risk for worsen AD. Environmental factors were also seen to modulate the effects of PM2.5 concentrations, specifically humidity levels due to seasonal changes and maintained indoor temperatures. PM2.5 was linked with a statistically and clinically significant increase in AD, with children, older people, and biological males at increased risk. This link is likely related to epidermal dysfunction, hormonal dysregulation, and heightened immune responses. These findings highlight the impact of air pollution exposure on skin disease morbidity and highlight the need for a high index of suspicion for environmental exposures when diagnosing and treating skin diseases.