To help asthmatics in Chennai
doctors treating asthma and allergies in Chennai now have a new tool to help them treat their patients. The city is the latest to have a pollen calendar. Researchers from Chennai-based Asthma & Allergy Research Centre, Raju Hospitals Private Limited and the University of Madras, recently carried out a survey of commonly present pollen grains in the air to prepare the map. "The map will help determine the type of pollen grains that are likely to have caused asthma," says V Raju, director of Raju Hospitals.
The air quality was monitored over a 12-month period (January-December, 2001). The group installed traps at five different locations -- Anna Nagar, Gandhi Mandapam, Royapettah, Villivakkam and Washermanpet -- to catch the pollen grains. Altogether 53 pollen types were recorded.
"Three factors were considered while preparing the map -- percentage of the pollen, capability of the pollen to cause allergy and buoyancy that controls its spread from one area to another," says N K Udaya Prakash, a consultant aerobiologist, who has worked on this project.
Maximum types of pollen grains were found in the southern part of the city, which has many trees. Pollen grains of Feronia elephantum, an exotic plant, were found in abundance. The concentration of pollen grains of different plants varied during the test period. Pollen grains of plants such as Cassia siamea, Cocos nucifera, Parthenium hysterophorus, Prosopis juliflor a and grasses were found throughout the year.
The group is currently involved in testing the allergy-causing proteins of the pollen grains to see the degree to which they can cause allergies. Till now, around 13 pollen types including those from Azadirachta indica (neem), Carica papaya (papaya), Cocos nucifera (coconut), Eucalyptus tereticornis (eucalyptus), Feronia elephantumn (wood apple), Parthenium hysterophorus (congress grass) and Ricinus communis (castor) have been tested. The study subjects were exposed to the allergy-causing protein. Congress grass was found to cause maximum allergy (17.4 per cent) followed by Casuarina (13 per cent).
"The map will help the patients take preventive measures during the period when they are likely to become allergic to a particular pollen. It would also help the doctor prescribe the most appropriate medication," says A B Singh, scientist at the Institute of Genomic and Integrative Biology, New Delhi. He feels that as the pollen grains keep changing according to the kind of plants that are introduced in a particular area, there is a need to continue updating the pollen maps. "Moreover, there is need for the authorities to be selective regarding the plants that are planted in an area," he suggests.
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