For the past 20 years, particulate matter (PM) pollution has been a national concern in South Korea. In particular, indoor PM concentrations may contribute significantly to human exposure. Elementary school students spend a lot of time in classrooms. Thus, PM in the classroom is one of important factors affecting the health of students. Therefore, South Korea is currently actively conducting various regulations and researches to reduce the concentration of particulate matter in elementary school classrooms. In this study, the concentration of PM and its influencing factors (such as occupants, room type, measurement height, aging of building, ventilation, presence of air purifiers, and indoor and outdoor environmental factors) in classrooms of elementary schools were investigated. Furthermore, measures and future study directions to diminish PM levels in classrooms were discussed. For this, approximately 160 peer-reviewed articles were reviewed. As a result, many studies showed that concentrations of PM in classrooms exceeded the recommended level by the World Health Organization (WHO). In particular, students living in Asia and Europe may be more exposed to PM in classrooms compared to other regions. On the other hand, the concentration of PM and PM2.5/PM10 ratio in classrooms are greatly affected by various indoor and outdoor influencing factors. Through this study, we intend to contribute to the establishment of related policies by understanding the factors that affect PM in elementary school classrooms.