Airborne rice pollen and pollen allergen in an agricultural field: aerobiological and immunochemical evidence

Abstract

Grass pollens are well known among the health hazardous bioaerosols causing respiratory allergy. Being an important member of the grass family, the rice plants contribute a huge pollen load in agricultural fields during flowering. This results in a seasonal trigger of hay fever and respiratory allergy in the field workers and people living in the vicinity. Studies on the monitoring of airborne rice pollen and the intensity of the released allergen in agricultural fields are largely lacking. The aims of the present study were: (1) daily and hourly monitoring of airborne rice pollen in an agricultural field during the flowering period of plants in a winter crop season by using the Burkard 7-Day Volumetric Sampler and (2) the measurement of hourly airborne allergen intensity in the field in a peak rice pollen period by the double-antibody and chemiluminescence techniques to find out its relationship with the airborne rice pollen concentration. The monthly average concentration of rice pollen was 95 pollen m(-3) and the range of daily average pollen concentration was 0 to 386 pollen m(-3). A bimodal diurnal periodicity showed that the airborne rice pollen concentrations remained high at two different times of the day: between 08:00 h to 12:00 h and 14:00 h to 16:00 h. Deposition of airborne rice pollen allergen showed darker intensities on the immunostained tapes from the Burkard Sampler at the same two positions corresponding to higher pollen counts. These observations provided direct evidence of the allergenicity of airborne rice pollen in field conditions.