Exposure to nitrogen dioxide (NO2), even for a short duration, between zero and seven days, leads to an increase in the number of emergency room visits by 53 per cent, according to a large study by AIIMS, Delhi. This is alarming because an increase in the levels of the more familiar pollutant PM 2.5 pushed up the patient load by 19.5 per cent in comparison. The study also found that the admissions were more among those suffering from other co-morbidities rather than just respiratory illnesses. About 68.2 per cent of people with other co-morbidities, who came in with respiratory symptoms, needed hospitalisation compared to 20.3 per cent with existing respiratory diseases. Though the study did not record other co-morbidities, experts say people with diabetes, hypertension and heart disease are at risk. NO2 levels are controllable as the gaseous pollutant is released when fossil fuels like petrol and diesel are burnt and are linked mainly to traffic. It is known to increase inflammation in the lungs, reduce lung function and increase wheezing and coughing. The particulate matter, on the other hand, is generated mainly due to construction activities and crop burning. “The particles lead to swelling and irritation in the respiratory system and are associated more with wheezing and coughing," says Dr SK Kabra, corresponding author of the paper. “This shows there is a need to curb pollution levels in the city as even short-term exposure leads to negative health consequences,” says Dr Karan Madan, one of the authors of the study and additional professor of respiratory medicine at AIIMS. “Whenever there is an increase in pollution levels, like now, there is an increase in the number of people coming in with symptoms such as difficulty breathing, wheezing and coughing,” he says. A majority of patients reported difficulty in breathing (95 per cent) and cough (74 per cent) as per the study. And, the symptoms lasted around three days. Those with other co-morbidities are more likely to need admission because pollution does not impact the respiratory system alone, it affects all organ systems. When a person has breathing difficulty, they need to breathe in more times to ensure adequate supply of oxygen to the body. When an adequate amount of oxygen does not reach the body on time, the heart has to pump more to keep up. “A person with an existing heart condition is, therefore, more likely to need more support to be stabilised," says Dr Kabra. He advises people living in crowded areas of Delhi, especially places like ITO and ISBT with high traffic congestion, to ensure that their windows facing the road remain closed. Not only that, there is an increase in the number of existing patients coming into AIIMS clinics with worsening and persistent symptoms when pollution levels increase in Delhi, according to Dr Madan. One of the interesting findings of the study was that the number of emergency visits went down by 26.1 per cent when the levels of carbon monoxide (CO) increased. While CO can be toxic in high quantities, the paper says that short term exposure to lower levels can actually reduce the inflammation caused by other pollutants. The study is based on the data of 69,400 patients who were brought to the AIIMS emergency department between June 2017 and February 2019. Of them, 13.3 per cent or 9,243 patients had respiratory symptoms. After factoring for whether the patients had these symptoms for less than two weeks and whether they were residents of Delhi for which pollution data was available, the data of 2,669 patients was compiled. While you may not be able to reduce pollution levels, Dr Madan suggests ways in which you can reduce your exposure. “People should try and stay indoors as much as possible when the pollution levels are high. They should especially avoid strenuous activities on high pollution days,” he says. As for people living with conditions like asthma and chronic obstructive pulmonary disease (COPD) – a group of lung diseases that make it difficult to breathe – Dr Madan suggests that they consult their doctor when the pollution levels start increasing. “They might need to increase their inhaler doses to prevent worsening of symptoms during the winters,” he says. As part of preventive routines, air purifiers may be more effective than masks. “The regular surgical masks do not really prevent small pollutants from entering our body. And, the N95 masks that can are very difficult to keep on for long durations. They are also more expensive,” adds Dr Madan. Air purifiers, on the other hand, may be useful for those who live with conditions like asthma and experience deteriorating symptoms every season. “It will not work in an open setting where the windows or doors are constantly replacing the air. But in an enclosed room, it may be helpful,” he says.
