Determination of the Influence of Fuel Switching Regulation on the Sulfur Dioxide Content of Air in a Port Area Using DID Model

Figure 6

SO₂ concentrations during periods of ship movement in or out of the dock versus periods of no movement of ship(s) in or out of the dock expressed in percentage terms. For each month (March, April, or May), SO₂ concentrations were divided into three categories: SO₂ concentrations at both monitoring points greater than 5 µg/m³ (both >5), SO₂ concentrations greater than 5 µg/m³ at only one monitoring station (one >5), SO₂ concentrations less than 5 µg/m³ at both stations (both <5).