Analysis of fine particulate matter blocking effect by air curtain at school entrance through experimental measurement

Fine particulate matter is classified as a first-class carcinogen and is receiving global attention. In particular, particulate matter (PM2.5, and PM10) are more fatal in students at a growing age while their respiratory system develops than in ordinary adults. During school hours, the main entrance is often left open for the convenience of students and staff. In this situation, the inflow of PM2.5 through the main entrance increases significantly. Thus, air curtains are widely used at the main entrance to block the inflow of PM2.5. However, few experimental studies have examined the effect of blocking PM2.5 through such air curtains. This study analyzed the effectiveness of reducing PM2.5 inflow by installing an air curtain at the main entrance of a school. The efficiency in blocking PM2.5 was determined by analyzing the average I/O ratio of PM2.5 at the respiratory height through experimental measurements. The average I/O ratio of PM2.5 in the school entrance was 0.84 before the installation of the air curtain, which was reduced to 0.46 after installing the air curtain. The blockage efficiency of the air curtain was 42%. This study quantitatively confirms that air curtains effectively reduce the inflow of PM2.5 in schools.