Comparison of Personal or Indoor PM Exposure Level to That of Outdoor: Over Four Seasons in Selected Urban, Industrial, and Rural Areas of South Korea: (K-IOP Study).

This study aimed to compare the distribution of indoor, outdoor, and personal PM (particulate matter ≤ 2.5 μm) hourly concentrations measured simultaneously among 81 nonsmoking elderly participants (65 years or older) living in urban, industrial, or rural areas over 4 seasons (2 weeks per season) from November 2021 to July 2022). PM measurements were conducted using low-cost sensors with quality control and quality assurance tests.