The study Dr Manas Ray headed was conducted between December 2002 and August 2005. It divided sample areas into different homogeneous strata based on air pollution level. Then sampling was done from each stratum randomly.
WHO WERE COMPARED
11,628 from Delhi
Children aged 4-17 from 36 schools; 7,757 (66.7%) boys and 3,871 (33.3%) girls
4,536 from elsewhere
Control group of children from 17 schools of rural Uttarakhand and West Bengal
The 36 Delhi schools, including government and private, were located within a 3 km radius of the air quality monitoring stations of Central Pollution Control Board and National Environmental Engineering Research Institute. They represented “every section of the people with comparable representations of children from low, medium and high socio-economic status”.
In the control arm, the 4,536 children were chosen from rural areas where the level of ambient air pollution was “much less for the absence of air polluting industries and a lower number of motor vehicles were enrolled. Two of the schools were in Khirsu and Kotdwar in Pauri-Garhwal district of Uttarakhand, and 15 were in Cooch Behar, South Dinajpur, Maldah, North and South 24-Parganas, and West Medinipur districts of West Bengal.
To determine the prevalence of respiratory symptoms, the study used a structured respiratory symptomlogy questionnaire based on international standards. The questions addressed symptoms such as attacks of shortness of breath, wheezing, dry or wet cough and chest tightness and included upper and lower respiratory symptoms. Associated symptoms like headaches, irritation in the eyes, nausea, palpitation and fatigue too were included.
Current asthma was prevalent in 4.6 per cent children of Delhi against 2.5 per cent of the controls. The instance of physician-diagnosed asthma, too, was two times more in Delhi. About 15 per cent of Delhi’s children had frequent eye irritation compared with only 4 per cent in the controls. Again, Delhi’s children had significantly higher prevalence of frequent headache, nausea, palpitation and fatigue.
5,718 Delhi children vs 2,270 in control, age 9-17
The results showed reduction of lung function in 43.5 per cent schoolchildren of Delhi compared with 25.7 per cent in the control group. Delhi’s children had a higher prevalence of restrictive, obstructive as well as combined (both restrictive and obstructive) type of lung functions deficits.
Besides higher prevalence, the magnitude of lung function impairment was much higher in Delhi. For example, 7.3 per cent schoolchildren of Delhi had severe lung function deficits compared with 2.2 per cent children in the control group. The prevalence of lung function reduction was highest during winter when the particulate pollution level was highest, and lowest in monsoon when the air is cleanest.
150 Delhi children vs 250 of the controls, age 13-15
Cells in Delhi’s children compared to those in control group
3.1 times higher
Alveloar macrophages in sputum
4 times higher
Neutrophils 42.2 30.6
Eosinzophils 3.2% 1.7%
In the sputum analysis study, the higher number of neutrophils in Delhi children, the study said, may suggest a greater prevalence of pulmonary infection and inflammation in the city. The higher percentage of eosinophils “indicates a greater prevalence of airway allergy”. Alveloar macrophages in sputum signify “greater exposure to particulate pollution”. Iron-laden macrophages indicate “covert pulmonary haemorrhage”.
1,082 Delhi kids vs 726 in control
HYPERTENSION was 6.2% more prevalent in Delhi compared with 2.1% in control.
2,630 of Delhi vs 1,645 from control, age 9-14
In attention deficit hyperactivity disorder (ADHD) screening., none of these children had a history of neurological problems such as epilepsy, autism, mental retardation, or sensory deficits, the study said, citing reports taken from parents and class teachers. Delhi’s children had 2.5 times higher ADHD prevalence than the controls.