New Delhi, Sep 21 (IANS): Pollen grains, whose levels are known to become higher during spring and fall, are among the main causes for serious allergic reactions and asthma attacks among the people in Delhi, said a new study on Wednesday.

The study, published in the Indian Journal of Allergy, Asthma, and Immunology, says not only vehicular pollution, but pollen in the atmosphere is also responsible for triggering respiratory allergy in more than 30 per cent of the population.

"Contrary to popular belief, not vehicular, it is the pollen grains, fungal spores, dust mites, insect debris and animal epithelial that include major causative agents," said the study conducted by the National Centre of Respiratory Allergy Asthma and Immunology, Vallabhbhai Patel Chest Institute.

"While pollens were already recognised as an important allergen, the study helped in understanding its detailed effects on respiratory systems," said Raj Kumar, Head, Department of Pulmonary Medicine, Vallabhbhai Patel Chest Institute.

"With a goal to determine the correlation between the pollen count variations with the weather conditions, the study presented comprehensive insights on how the rise in pollens in spring increases the patient count in winters as well."