Air pollution has increasingly been recognized as a major healthcare concern. Air pollution, particularly fine particulate matter (≤ 2.5 μm in aerodynamic diameter [PM2.5]) has demonstrated an increase in adverse cardiovascular events. This study aimed to assess the cardiovascular response to personal exposure to different levels of PM2.5. This prospective cohort study enrolled healthy volunteers aged ≥ 18 years with no cardiovascular disease. Study subjects carried personal exposure monitor of PM2.5, digital thermo-hygrometer for temperature and humidity, 24-h blood pressure monitor, and continuous electrocardiogram monitor. Measurements were repeated twice with an interval of 6-12 months. Statistical models consisted of generalized estimation equations to various repeated measures of each subject. A total of 22 subjects were enrolled in this study between July 2018 and January 2019. Measurement was performed twice in all participants, and a total of 36 data were collected except for insufficient data collection. The mean age of the study population was 41.6 years, and 95% of the subjects were females. No study subjects had hypertension or other cardiovascular diseases. The average systolic blood pressure increased with higher PM2.5 levels with marginal significance (0.22 mmHg [95% confidential intervals - 0.04 to 0.48 mmHg] per 10 μg/m3 of PM2.5). All parameters for heart rate variability significantly decreased with a higher level of PM2.5. In this study, we measured individual personal exposure to PM2.5 by using a portable device. We found that 24-h exposure to high levels of PM2.5 was associated with a significant decrease in heart rate variability, suggesting impaired autonomous nervous function.