Effects of ambient air pollution on emergency room visits of children for acute respiratory symptoms
Authors: Yadav Rashmi , Nagori Aditya , Mukherjee Aparna , Singh Varinder , Lodha Rakesh , Kabra Sushil Kumar ,   Air pollution study group
Published: November 2020

Background

Data on the relation between the increase in ambient air pollution and acute respiratory illness in children are scarce. The present study aimed to explore the association between daily ambient air pollution and daily emergency room (ER) visits due to acute respiratory symptoms in children of Delhi.

Methods

In this epidemiological study, the daily counts of ER visits (ERV) of children (≤15 years) having acute respiratory symptoms from 1stJune 2017 to 28thFebruary 2019 were obtained from two general hospitals of Delhi. Simultaneously, data on daily average concentrations of particulate matter (PM10and PM2.5), nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), and ozone (O3), and weather variables were provided by Delhi Pollution Control Committee from their four continuous ambient air quality monitoring stations. We used K-means clustering with time-series approach to derive pollutant-derived clusters and the study period was categorized into high, moderate and low air pollution days. The combined effect of these air pollutants on acute respiratory ERV was assessed. Multi-pollutant generalized additive models (GAM) with Poisson link function was used to estimate the 0-6 day lagged change in daily ER visits with the change in multiple pollutants levels, adjusting for weather variables, days of the week and public holidays.

Results

In 21 months, 132,029 children were screened at the ER of the participating hospitals. Of these 19,320 (14.6%) were eligible, and 19120 were enrolled with complete data collection. The study period could be divided into 3 pollutant-derived clusters with high (Cluster 1, 150 days), moderate (Cluster 2, 204 days) low (Cluster 3, 284 days) levels of air pollution. There was a 28.7% and 21% increase in ERV among children respectively, on high and moderate level pollution days (Cluster 1 and 2) compared to low pollution days (Cluster 3) on the same day of exposure to air pollutants. Similar results were found when the exposure to ambient air pollution of previous 1-6 days were taken into account. GAM analysis showed that the association of the acute respiratory ER visits with every 10 unit change of PM10,NO2, O3,CO and SO2remained significant after adjusting for multi-pollutant and confounding variables effects. In contrast, no effect was seen for PM2.5. The ERVs for acute respiratory symptoms rose with increase in pollutants and the trends showed a percentage change (95% CI) 1.07% (0.32, 1.83) increase in ERVs for an increase of 10 micrograms per cubic meter of NO2at previous day 1, 36.89% (12.24,66.95) for 10 milligrams per cubic meter of CO at previous day 3, and 12.77% (9.51, 16.12) for 10 micrograms per cubic meter of SO2at same day while decrease of −0.18% (−0.32, - 0.03) for 10 micrograms per cubic meter of PM10at same day, and −4.16 % (−5.18, −3.13) for O3at previous day 3.

Conclusion

An increase in the daily ER visits of children for acute respiratory symptoms was seen for 1-6 days after increase in daily ambient air pollution levels in Delhi.