A relational analysis of acute wheezing and air pollution

Abstract

Objective To correlate hospital attendance for wheezing treated with nebulizer therapy with pollutant levels recorded in ambient air in Colombo. Setting Emergency treatment unit (ETU) of the Lady Ridgeway Hospital, Colombo. Design A prospective observational case control study. Method Attendance at the ETU for nebulizer therapy was recorded daily for 12 months. ETU attendance for conditions other than wheezing served as controls. The case and control attendance rates were correlated with daily maximum and minimum one hour average levels of sulfur dioxide and oxides of nitrogen in ambient air as measured by the continuous pollution monitor situated in the Fort, Colombo. Results 30,932 children needed nebulizer therapy in the ETU (median daily attendance 85) during the period of 12 months. The control population was 10,100 children (median daily attendance 28). The pattern of pollutant levels and attendance rates for wheezing showed a correlation on a time series. Conclusion Air pollution levels in Colombo correlated significantly with hospital attendance rates for wheezing needing emergency treatment. The highest recorded levels of sulfur dioxide and oxides of nitrogen in ambient air showed a significant correlation with the highest hospital attendance rates, and the lowest pollutant levels with the lowest hospital attendance rates. We conclude that vehicle related pollutants in ambient air in Colombo are affecting the respiratory health of children. _________________________________________ Senior Lecturer in Paediatrics, Faculty of Medicine, Colombo, 2 Scientist, Environmental Division, National Building Research Organization, Colombo, 3 Medical Officer, Lady Ridgeway Hospital, Colombo, 4 Project Assistant, Environmental Division, National Building Research Organisation, Colombo. Introduction Epidemiological data shows a significant increase in childhood asthma throughout the world, in the past three decades 1,2,3,4 . This sharp rise in incidence and prevalence of acute wheezing is believed to be environmental and not genetic in aetiology 5 . Air pollution has been documented to contribute to respiratory disease and wheezing in children and is a public health concern in many cities 6,7,8,9,10,11 . Automotive emissions are considered the major source of air pollution in urban areas 11 . In Sri Lanka, respiratory diseases are the leading cause of hospitalisation in children and the second commonest cause at all ages 12 . The numbers of children needing bronchodilator therapy at the Lady Ridgeway Hospital, Colombo is increasing each year. There has been a steep incline in the vehicle population in Sri Lanka over the last 25 years. The traffic in Colombo grows by 5% each year and it is estimated that 50% or more of the total vehicle fleet of Sri Lanka plies in the Colombo metropolitan area 13 . The exposure of the city dwelling child to automotive air pollution needs attention. We investigated for an association between hospital attendance for episodes of severe wheezing and air pollutant levels in the city.