Quantifying Health Benefits of Stricter PM Standards: A Comparison of EU and WHO Annual Guidelines

Inhalation of particulate matter (PM) is associated with respiratory, cardiovascular, and systemic health effects. In 2019, global outdoor PM exposure caused over 4.2 million premature deaths, according to the World Health Organization (WHO, 2024). Reducing PM exposure is therefore essential. This study compares outdoor European Union (EU) air quality standards (Directive 2008/50/EC) with outdoor WHO guidelines, focusing on mean annual concentrations of PM₂.₅ and PM₁₀ and their associated health impacts (WHO, 2021). These impacts were quantified using Disability-Adjusted Life Years (DALYs) per 100,000 people. Findings show that EU standards for mean annual PM₂.₅ (20 µg/m³) and PM₁₀ (40 µg/m³) are substantially higher than WHO recommendations (5 µg/m³ and 15 µg/m³, respectively), resulting in significant health impacts. Estimated burdens under current EU standards are 1,390 (95% CI: 1,377–1,403) and 1,990 (95% CI: 1,978–2,003) DALYs per 100,000 people annually for PM₂.₅ and PM₁₀, compared to 350 (95% CI: 345–355) and 740 (95% CI: 735–745) DALYs under WHO guidelines. In March 2024, the EU proposed updating its standards to more closely align with WHO goals, including reducing PM₂.₅ to 10 µg/m³ by 2030, still double the WHO guideline. As outdoor PM significantly influences indoor concentrations through ventilation and infiltration, and people spend most of their time indoors, this study also evaluates the influence of outdoor concentration on indoor exposure via case studies of a hospital waiting room and a three-bedroom apartment. Results show that, in absence of strong indoor sources, outdoor PM concentrations significantly impact indoor air quality (IAQ) through ventilation and building infiltration, leading to indoor concentrations that nearly match those outdoors. These findings emphasize the critical need for strict outdoor air quality standards and effective ventilation strategies to maintain safe indoor environments. Overall, this analysis supports the substantial public health benefits of aligning EU standards with WHO guidelines to reduce the disease burden associated with PM exposure.