'March epidemic' of asthma

Subhra Priyadarshini

doi:10.1038/nindia.2012.36 Published online 14 March 2012

Seasonal spurts in asthma cases have been reported from across the world. Researchers in the Indian megacity of Kolkata have now found evidence to nail a 'March epidemic' of asthma. They found that asthma-related hospital admissions (ARHA) went up significantly in the months of March and September. A similar trend in countries such as US, Australia and Canada has earlier been nick-named the 'September epidemic' after the month when ARHA peaks there.

In Kolkata, more than 40% of the annual asthma-related hospitalisation was found to be during these two months over seven consecutive years.

"Consistency of this seasonal pattern, along with the amplitude of the peaks in relation to the rest of the yearly cycle, suggests the presence of one or more consistent factor(s) influencing asthma exacerbation," says lead researcher Debajyoti Ghosh, currently working at the Allergy & Rheumatology University of Cincinnati College of Medicine in Ohio, US.

In general, asthma symptoms can be exacerbated by high allergen and pollutant load oin the atmosphere. However, the key factors vary from place to place.

"Kolkata represents a densely populated environment with high concentrations of air-pollutants and rich tropical/sub-tropical vegetation. We recorded the numbers of allergenic pollen grains and fungal spores that were present in per liter of ambient air per day," Ghosh told Nature India.

The team comprising researchers from Sree Chaitanya College, West Bengal; University of Pennsylvania School of Medicine, USA; and Kolkata-based Indian Statistical Institute, Institute of Child Health and Bose Institute studied concentrations of gaseous and particulate air pollutants. They also looked at the daily numbers of asthma-related hospitalization cases.

Statistical modeling of the data showed that apart from natural exposure of grass/weed pollen, respirable particulate matter pollutants were strongly associated to Asthma-related hospital admissions in the mega-city.


  1. Ghosh, D. et al. Asthma-related hospital admissions in an Indian megacity: role of ambient aeroallergens and inorganic pollutants. Allergy 65, 791-804 (2010) | PubMed |