Assessing atmospheric pollution in a petrochemical industrial district using a lichen-air quality index (LiAQI)

Physiological processes within the thalli of lichens respond differently to accumulated pollutants. The chemical and physiological responses of lichens to atmospheric pollution from a petrochemical industrial complex were used to develop a lichen-air quality index (LiAQI). Thalli of the lichen Parmotrema tinctorum collected from an unpolluted area were transplanted to eight monitoring sites in the surrounding area of the Map Ta Phut industrial estate, two sites in an agricultural zone and a control site in a national park. Thirty chemical substances and eight physiological parameters were measured and analyzed. These data were then used to calculate the LiAQI of each monitoring site. The LiAQI values suggested that three industrial sites within 3-5 km of the main industrial area had poor air quality, three sites at a distance of 4-7 km had moderate air quality and two sites at a distance of 8-9 km had good air quality. Both agricultural sites at a distance of 35-55 km had very good air quality when compared with the control site. Air quality was found to improve with greater distance from the industrial center. The LiAQI developed from lichens was effective at detecting atmospheric pollution.