Air Pollution as a Risk Factor for Intracerebral Hemorrhage

While hypertension remains the dominant global intracerebral hemorrhage risk factors (ICH), recent evidence highlights air pollution — particularly fine particulate matter (PM2.5) — as an emerging and independent contributor to ICH burden.

• Endothelial dysfunction: PM2.5 induces systemic oxidative stress and inflammation, weakening cerebral vasculature.
• Blood pressure elevation: Acute and chronic exposure can raise systolic BP, triggering hemorrhagic events.
• Pro-thrombotic state: Inflammatory cytokines promote vascular fragility and coagulation imbalance.
• Exacerbation of small vessel disease: Chronic pollution worsens cerebral microangiopathy, increasing hemorrhagic susceptibility.

• PM2.5 exposure correlates with higher ICH incidence and mortality.
• Stronger impact observed in low- and middle-income countries and urban settings.
• Socioeconomic disparities modulate exposure and outcomes.
• Longitudinal data confirm environmental exposure as a modifiable stroke risk.

Wu E. et al. (2025) Ambient versus household PM2.5 exposure and socioeconomic disparities in intracerebral hemorrhage burden: A 32-year global analysis (1990–2021) Front Public Health. 2025;13:1615934. doi:10.3389/fpubh.2025.1615934

• Global study modeling ICH burden linked to ambient vs household PM2.5.
• Ambient PM2.5 associated with greater burden in high-income countries.
• Household air pollution more relevant in low-income settings.
• Projection: ICH burden from PM2.5 will continue rising through 2050.

• Air quality control should be part of stroke prevention strategies.
• High-risk populations (e.g., elderly hypertensives in polluted areas) require targeted interventions.
• Environmental policy should incorporate cerebrovascular health outcomes.

• Air pollution should be considered in ICH risk stratification.
• Clinicians may advise high-risk patients on pollution avoidance during peaks.
• Future risk models may integrate environmental exposure metrics.

In a ecological trend analysis with global burden modeling Wu et al. from the Xinjiang Medical University, Ürümqi; University of A Coruña, published in Frontiers in Public Health to evaluate the global burden of PM2.5-attributable intracerebral hemorrhage (ICH) from 1990–2021, analyze trends by exposure source ambient PM2.5 (APMP) vs. household [HAP]), and project disparities through 2050 stratified by Socio-demographic Index (SDI). PM2.5 exposure—particularly household-related in low Socio-demographic Index regions—continues to drive significant intracerebral hemorrhage mortality and morbidity despite global reductions in age-standardized rates. Disparities persist, with low SDI areas experiencing a 24.7-fold higher Age-Standardized Mortality Rate (ASMR )than high SDI regions. Projections indicate a resurgence in PM2.5-related ICH burden by 2050, emphasizing the need for tailored public health interventions targeting APMP and HAP, especially in Asia and Sub-Saharan Africa ¹⁾

Critical Review:

While commendable in scale and data synthesis, the study leans heavily on GBD-derived estimates with inherent limitations in data completeness, exposure modeling accuracy, and attribution logic. The ecological design limits causal inference, and the projections to 2050 are based on statistical models without incorporating policy or behavioral change scenarios. Stratification by SDI is informative but overly coarse for actionable policy translation.

The study's primary novelty—disentangling APMP vs. HAP contributions—is valuable, but it relies on indirect estimations rather than direct exposure measurements or cohort validations. The assumption of uniform exposure-response relationships across regions may oversimplify biologic and demographic nuances. Moreover, the clinical implications for neurosurgeons are abstract: while population health trends are important, no direct relevance to surgical practice or ICH management is explored.

Final Verdict:

A solid global epidemiological effort that contributes to understanding environmental risk stratification in ICH, but offers limited clinical utility and relies heavily on modeled data without validation. Its strength lies in illuminating socioeconomic and demographic disparities rather than providing actionable insights for neurosurgical care.

Takeaway for the Practicing Neurosurgeon:

Recognize the global health inequities in ICH risk attributable to air pollution—especially household PM2.5 in low-resource settings—but this does not alter current surgical management paradigms.

Bottom Line: Important from a public health standpoint; marginal direct relevance to neurosurgical practice.

Rating: 5.0 / 10

Publication Date: June 18, 2025

Spontaneous intracerebral hemorrhage (sICH) has a high mortality rate. Research has demonstrated that the occurrence of sICH is related to air pollution. This study used big data analysis to explore the impact of air pollution on the risk of sICH in patients of differing age and geographic location. 39,053 cases were included in this study; 14,041 in the Taipei region (Taipei City and New Taipei City), 5537 in Taoyuan City, 7654 in Taichung City, 4739 in Tainan City, and 7082 in Kaohsiung City. The results of correlation analysis indicated that there were two pollutants groups, the CO and NO₂ group and the PM2.5 and PM10 group. Furthermore, variations in the correlations of sICH with air pollutants were identified in different age groups. The co-factors of the influence of air pollutants in the different age groups were explored using regression analysis. This study integrated Taiwan National Health Insurance data and air pollution data to explore the risk factors of sICH using big data analytics. They found that PM2.5 and PM10 are very important risk factors for sICH, and age is an important modulating factor that allows air pollutants to influence the incidence of sICH ²⁾.