對環境大氣（空氣）中(zhong)污染物濃度的表示方法有兩種：

1、質(zhi)(zhi)量(liang)(liang)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)表(biao)(biao)示法：每立方(fang)米空氣(qi)(qi)中(zhong)所含(han)污(wu)(wu)染(ran)物(wu)的質(zhi)(zhi)量(liang)(liang)數，即mg/m32、體(ti)(ti)(ti)(ti)積(ji)(ji)(ji)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)表(biao)(biao)示法：一百(bai)萬體(ti)(ti)(ti)(ti)積(ji)(ji)(ji)的空氣(qi)(qi)中(zhong)所含(han)污(wu)(wu)染(ran)物(wu)的體(ti)(ti)(ti)(ti)積(ji)(ji)(ji)數，即ppm 大部分氣(qi)(qi)體(ti)(ti)(ti)(ti)檢測儀器(qi)測得的氣(qi)(qi)體(ti)(ti)(ti)(ti)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)都(dou)(dou)是(shi)體(ti)(ti)(ti)(ti)積(ji)(ji)(ji)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)（ppm）。而(er)按我(wo)國規定，特(te)別是(shi)環(huan)保部門(men)，則要求氣(qi)(qi)體(ti)(ti)(ti)(ti)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)以質(zhi)(zhi)量(liang)(liang)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)的單(dan)(dan)位(wei)(wei)（如(ru)：mg/m3）表(biao)(biao)示，我(wo)們國家的標準規范(fan)也都(dou)(dou)是(shi)采用質(zhi)(zhi)量(liang)(liang)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)單(dan)(dan)位(wei)(wei)（如(ru)：mg/m3）表(biao)(biao)示。 這(zhe)兩種氣(qi)(qi)體(ti)(ti)(ti)(ti)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)單(dan)(dan)位(wei)(wei)mg/m3與(yu)ppm有何(he)關系呢(ni)？其(qi)間如(ru)何(he)換(huan)算(suan)(suan)？ 使(shi)用質(zhi)(zhi)量(liang)(liang)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)單(dan)(dan)位(wei)(wei)（mg/m3）作為(wei)空氣(qi)(qi)污(wu)(wu)染(ran)物(wu)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)的表(biao)(biao)示方(fang)法，可以方(fang)便(bian)計算(suan)(suan)出(chu)污(wu)(wu)染(ran)物(wu)的真正量(liang)(liang)。但(dan)質(zhi)(zhi)量(liang)(liang)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)與(yu)檢測氣(qi)(qi)體(ti)(ti)(ti)(ti)的溫(wen)度(du)(du)(du)(du)、壓(ya)力(li)(li)環(huan)境(jing)條(tiao)(tiao)件有關，其(qi)數值(zhi)(zhi)會隨著溫(wen)度(du)(du)(du)(du)、氣(qi)(qi)壓(ya)等(deng)環(huan)境(jing)條(tiao)(tiao)件的變化而(er)不(bu)同；實(shi)際測量(liang)(liang)時需要同時測定氣(qi)(qi)體(ti)(ti)(ti)(ti)的溫(wen)度(du)(du)(du)(du)和大氣(qi)(qi)壓(ya)力(li)(li)。而(er)在(zai)使(shi)用ppm作為(wei)描述污(wu)(wu)染(ran)物(wu)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)時，由于采取(qu)的是(shi)體(ti)(ti)(ti)(ti)積(ji)(ji)(ji)比，不(bu)會出(chu)現這(zhe)個問題。 濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)單(dan)(dan)位(wei)(wei)ppm與(yu)mg/m3的換(huan)算(suan)(suan)：按下式(shi)計算(suan)(suan)： 質(zhi)(zhi)量(liang)(liang)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)mg/m3=M氣(qi)(qi)體(ti)(ti)(ti)(ti)分子(zi)量(liang)(liang)/22.4*ppm數值(zhi)(zhi)*[273/（273+T氣(qi)(qi)體(ti)(ti)(ti)(ti)溫(wen)度(du)(du)(du)(du)）]*（Ba壓(ya)力(li)(li)/101325）M為(wei)氣(qi)(qi)體(ti)(ti)(ti)(ti)分子(zi)量(liang)(liang)，ppm為(wei)測定的體(ti)(ti)(ti)(ti)積(ji)(ji)(ji)濃(nong)(nong)(nong)(nong)(nong)度(du)(du)(du)(du)值(zhi)(zhi)，T為(wei)溫(wen)度(du)(du)(du)(du)、Ba為(wei)壓(ya)力(li)(li)，如(ru)果濕度(du)(du)(du)(du)很大時，例(li)如(ru)在(zai)100%相對濕度(du)(du)(du)(du)下，還需另外一項(xiang)。

氣(qi)(qi)體分(fen)子(zi)(zi)量？從哪得(de)來？別急！我們有(you)個氣(qi)(qi)體分(fen)子(zi)(zi)量的(de)(de)計(ji)算(suan)軟件(jian)呢—只要你把該氣(qi)(qi)體的(de)(de)分(fen)子(zi)(zi)式一輸入(ru)，馬(ma)上(shang)就得(de)到其氣(qi)(qi)體分(fen)子(zi)(zi)量！神(shen)吧！下載氣(qi)(qi)體分(fen)子(zi)(zi)量計(ji)算(suan)軟件(jian)： —本軟件(jian)支持所化(hua)(hua)學領(ling)域可能會(hui)出現的(de)(de)化(hua)(hua)學式，支持含(han)有(you)中、小括(kuo)號的(de)(de)化(hua)(hua)學式（可嵌套），支持有(you)機化(hua)(hua)合物中單鍵、雙鍵、叁(san)鍵符號的(de)(de)輸入(ru)，支持含(han)有(you)非整(zheng)數的(de)(de)系數與角標(biao)的(de)(de)化(hua)(hua)學式，支持含(han)有(you)同(tong)位(wei)素(su)符號的(de)(de)化(hua)(hua)學式，等等。計(ji)算(suan)結果將給出式量、最簡(jian)式、元素(su)含(han)量統計(ji)。[常見(jian)氣(qi)(qi)體分(fen)子(zi)(zi)量： 甲醛HCHO為(wei)30.0260,苯C6H6為(wei)78.1118,氨NH3為(wei)17.0306