Silent Lung Risk: 4 Percent of Indian Teens Show Asymptomatic Bronchial Hyperresponsiveness, APEAL Study Finds

The study was part of the APEAL (Air Pollution Exposure on Adolescents' Lungs) project, which involved 4,141 adolescents aged 11 to 14 years from Mysuru, Bengaluru, Mumbai, and Delhi. All participants had no history of asthma symptoms or any prior diagnosis of chronic respiratory disease, making the presence of BHR in this population particularly significant. Researchers used standardized pulmonary function testing to detect BHR, defined as a post-bronchodilator increase in FEV1 (forced expiratory volume in one second) of at least 12% and 200 mL.

The study presented the following key findings:

• 4.0% of adolescents met the criteria for asymptomatic BHR.
• Prevalence varied by city: Mumbai (5.6%), Delhi (4.5%), Bengaluru (4.2%), and Mysuru (2.3%).
• Younger adolescents were more susceptible (odds ratio [OR] = 1.48).
• PM2.5 exposure was a strong risk factor: exposure between 64.1–124.8 µg/m³ increased BHR risk by 83% (OR = 1.83), and levels above 124.8 µg/m³ more than doubled the risk (OR = 2.56).
• Underweight adolescents were at greater risk of severe airflow limitation.
• Interestingly, being overweight appeared to have a protective effect, although obesity showed a similar trend, it was not statistically significant due to fewer participants in that category.

According to the authors, the results highlight the limitations of symptom-based asthma screening, which can miss early airway changes in children who appear healthy. They advocate for routine lung function testing in schools, especially in pollution-heavy urban centers to enable early identification and prevention of chronic respiratory diseases.

Despite some limitations—such as its single-time assessment and city-specific sampling differences—the study's multicentric approach and use of international protocols, such as BOLD and GAN, lend credibility to its findings. The authors urge the need for long-term monitoring of affected individuals and targeted public health strategies.

Dr. Mahesh and his team concluded, “The APEAL study highlights a silent epidemic of early airway changes in Indian adolescents, calling for a shift in asthma detection strategies to include objective lung testing, especially in high-risk urban settings.”

Reference:

Mahesh, P. A., Ullah, M. K., Greeshma, M. V., Patil, S., Samdarshi, P., Veerabhadraiah, H., Khayum, A., Agrawal, T., Phuleria, H. C., Wellenius, G., Nori-Sarma, A., Ponnuraj, L., Kagalavadi Mahadevaswamy, S. K., Mayigaiah, S. C., Thimmulappa, R. K., & Mohan, A. Prevalence of Asymptomatic Bronchial Hyperresponsiveness in Indian Adolescents: Insights From the APEAL Study. Clinical & Experimental Allergy. https://doi.org/10.1111/cea.70110