“…Correlation with COx Sources Wind speed Negative [45], [38], [39], [49], [43], [40], [37], [47], [41], [44], [46], and [42] Spaces The outdoor PM level influences indoor PM concentration, which will be advantageous if the outdoor level is lower than the indoor and will be detrimental if the outdoor level is higher than indoor [42]. This detrimental effect happen in other studies showing that longer opening times worsened indoor air by increasing PM levels, this due to high concentration of outdoor PM levels [39] [48].…”