Effect of airborne Alternaria conidia, ozone exposure, PM10 and weather on emergency visits for asthma in school-age children in Kolkata city, India

Alternaria is one of the important allergenic fungal spores having special role in childhood asthma. Aerodynamic particle of < 10 mu m diameter (PM10) and ozone exacerbate respiratory conditions including asthma. There is no documentation determining the role of airborne concentration of Alternaria conidia, pollutants like PM10 and ozone and weather on school-age (5-18 years) children causing life-threatening episodes requiring emergency hospitalization for asthma in the megacity of Kolkata, Eastern India. We examined the relationship of daily hospitalization for asthma in school-age children and daily concentration of outdoor Alternaria conidia, ozone, PM10 and weather parameters in the atmosphere of Kolkata during 2010 using nonparametric generalized additive model (GAM). After a baseline survey (2008-2009), asthma hospitalization data for school-age children (based on case history and symptom-medication) were collected from two important city hospitals near study area in 2010. Daily Alternaria concentration was recorded using Burkard volumetric sampler. Its allergenic potential was confirmed by skin reactivity. Ozone and PM10 concentration data were collected from West Bengal Pollution Control Board. The daily time series analyses of data were performed using GAM. There are two peak seasons of asthma hospitalization, one in spring-early summer (end of March to mid April) and other in autumn (mid September-October). In GAM analyses, Alternaria conidia, ozone and PM10 were found to be significant both in spline and LOcal regrESSion smoothing method. Airborne Alternaria conidia, ozone and PM10 in the city of Kolkata are found to have effect on school-age children with asthma and appear responsible for severe attacks leading to hospitalization.