Contrary to popular belief that trees fight pollution, several species of plants including cashew, tamarind, guava, mango, custard apple, gulmohar, banyan, sapota and jackfruit, are falling prey to heavy air pollution in the industrial city of Visakhapatnam. Researchers from the departments of chemistry, and environmental studies, GITAM University, Visakh-apatnam, have found that many plant species have been experiencing “physiological changes” due to heavy air pollutants before exhibiting visible damage to leaves. The content of chlorophyll has come down in many trees affecting the delicate process of converting carbondioxide into oxygen. It has also affected food preparation by the trees, and thus reduction in their fruit yield and growth. Of the 29 trees studied, only six fell under the “moderately tolerant” to air pollutants category. None of these are tolerant to chemicals present in the air. Only those trees that are tolerant to heavy air pollutants are capable of fighting pollution in industrial belts, and reducing its impact on human beings, animals and other plants. The research was conducted separately by N. Srinivas and others from department of environment studies, and A. Sunil Dadhich and team from the department of chemistry. Peepal, jujube, amla, cassia, lemon and neem are moderately tolerant to pollution. A majority of trees fall in the sensitive category. This means growing these trees in industrial belts and highly polluted areas will do more harm than good to the environment. “Trees can be used as both passive biomonitors and bio-mitigators in the urban industrial environment to indicate the environmental quality and to ameliorate the pollution levels. Air pollutants can directly affect plants via leaves. The level of injury is high in sensitive species and low in tolerant ones,” the researchers said. The teams studied the content of chlorophyll and ascorbic acid, relative humidity, pH and air pollution tolerance index (APTI) of trees selected.