Hyderabad: Children living in urban areas are at increased risk of asthma attacks due to a rise in the level of pollutants in the air. Significantly, most viral respiratory infections are considered responsible for asthma, but a recent study published in the Lancet Planetary Health, reveals that non-viral factors such as pollutants in the air in urban areas, especially ozone and other fine particles, are increasing the risk of triggering asthma attacks in children. The study analyzed the association between air pollution and all-cause asthma attacks.
The study suggests that high pollution levels in the air, especially ozone and other particulate matter, can trigger asthma attacks and impair lung function, especially in children living in urban localities. These particles can also cause degradation of the lungs, even if their concentration or amounts in the air are below national air quality standards.
Dr Alan Dodger, professor of Paediatrics and Head of the Department of Pulmonology at New York Medical College and one of the researchers, says that viral infections associated with asthma are very common in children. He says that the most severe cases of asthma are attributed to Upper Respiratory Tract Infections (URIs) or colds, which increase the number of cases of viral infections and asthma every year, especially during winter.
In areas with higher levels of air pollution, severe asthma attacks are more common during the winter season. This research has revealed that high levels of air pollution worsen both, viral and non-viral-associated asthma attacks. But, individual exposure to air pollutants may differ for people living in the same localities.
In the study, the researchers first examined the association between asthma severity in children and adolescents living in certain urban areas of the US and air pollutant levels in their cities. They also analyzed data from some older observational studies and the gene expression profiles of the participants, to understand the underlying molecular mechanism and molecular basis of viral and non-viral asthma exacerbation.
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For this study, the authors used MUPPITS1 (Mechanisms Underlying Asthma Exacerbations Prevented and Persistent With Immune-Based Therapy) participants and their data. Significantly, MUPPITS1 included data from 208 children aged 6 to 17 who had acute-prone asthma from living in low-income neighbourhoods in nine cities in the United States.
In this study, data on lung function and nasal samples were collected from the time of onset of symptoms of respiratory illness in these participants to investigate the differences in general studies and gene expression. The researchers also used nasal samples to determine whether the respiratory illness was caused by a viral infection or a non-viral factor. In this research, the participants were also classified based on whether they had an asthma attack during the infection or not.
In addition, the researchers also used data on the air quality index and concentrations of individual pollutants collected by the Environmental Protection Agency (EPA) to examine the amount of pollution in the geographic area of study participants. In addition to MUPPITS1, the research also used data from another study of 419 individuals aged 6 to 20 living in low-income households in eight major US cities.
Based on the data from participants in the MUPPITS1 study, it was found that participants with non-viral asthma exacerbations had higher air quality index values before and nine days after symptom onset than those with viral asthma exacerbations. In addition, air quality index values were negatively correlated with lung function in participants with non-viral asthma exacerbations. The gene expression was observed in both, viral and non-viral causes of asthma in the research.
In another study, a similar association was observed between the air quality index and the prevalence of non-viral asthma. Data from both these studies revealed that ozone and fine particulate matter (PM2.5) concentrations were higher in the residential areas of children with non-viral asthma attacks.
In this study, the researchers have also said that more in-depth investigation is needed on this topic. Since the number of subjects in this study was small and data related to air pollution was used from monitors, more studies should be conducted on this topic with more data and better spatial air pollution resolution for more accurate and clear information.
