Using the Quarterly Compound Fractional Grey Model to Predict the Air Quality in 22 Cities of China

<table class="table-group" id="tab5"><tr><td><table class="table"><tr><td class="thead-hr" colspan="3"><hr/></td></tr><tr class="thead"><td class="align_left">Pollutants</td><td class="align_center">Level 1 (unit: <i>μ</i>g/m<sup>3</sup>)</td><td class="align_center">Level 2 (unit: <i>μ</i>g/m<sup>3</sup>)</td></tr><tr><td class="thead-hr" colspan="3"><hr/></td></tr><tr><td class="align_left">PM<sub>2.5</sub></td><td class="align_center">15</td><td class="align_center">35</td></tr><tr><td class="align_left">PM<sub>10</sub></td><td class="align_center">40</td><td class="align_center">70</td></tr><tr><td class="align_left">SO<sub>2</sub></td><td class="align_center">20</td><td class="align_center">60</td></tr><tr><td class="align_left">NO<sub>2</sub></td><td class="align_center">40</td><td class="align_center">40</td></tr><tr class="table-tr"><td colspan="3"><hr class="tbody-hr"/></td></tr></table></td></tr></table>

<div>Quality levels and corresponding concentration limits of PM<sub>2.5</sub>, PM<sub>10</sub>, SO<sub>2</sub>, and NO<sub>2</sub>.</div>

Journal of Mathematics

tab5

Table 5

Table 5: Using the Quarterly Compound Fractional Grey Model to Predict the Air Quality in 22 Cities of China 