Q.Assertion (A) : More and more children in metro cities of India suffer from allergies and asthma due to sensitivity to the environment. Reason (R) : Modern day lifestyle and a protected environment in early life has resulted in lowering the immunity.

Concept: Hygiene hypothesis and immune system development

The hygiene hypothesis explains that reduced exposure to microbes and pathogens during early childhood—common in urban, sanitized environments—limits the maturation of the immune system. When children grow up in overly protected settings with minimal microbial challenge, their immune systems fail to develop proper regulatory mechanisms. …

The Hygiene Hypothesis and Urban Health Trends

The question asks you to evaluate two linked statements about childhood health in Indian cities. Understanding this requires familiarity with a well-established concept in immunology: the hygiene hypothesis.

Our immune system develops through exposure. When young children encounter diverse microbes—bacteria, viruses, parasites—their immune systems learn to distinguish real threats from harmless substances. In overly sanitized environments, this training is incomplete. The immune system, lacking proper "education," begins overreacting to benign triggers like pollen, dust mites, or pet dander. This misdirected response manifests as allergies and asthma.

Metro cities in India present a perfect storm: air pollution, enclosed air-conditioned spaces, reduced outdoor play, excessive use of antibacterial products, and smaller family sizes (fewer infections shared among siblings). Children grow up in what immunologists call a "protected environment"—paradoxically making them more vulnerable.

Evaluating Each Statement

1. Assertion (A) is factually correct.

   Epidemiological data from Indian metros (Delhi, Mumbai, Bangalore) show a documented rise in childhood allergic rhinitis, asthma, and atopic dermatitis over the past two decades. The prevalence has increased from roughly 10–15% to 20–30% in urban populations, while rural rates remain lower. This is an observed, measurable trend.

2. Reason (R) is also correct.

   Modern lifestyle factors—smaller living spaces, reduced microbial exposure, dietary changes, increased antibiotic use—have been shown to suppress early immune system development. The "protected environment" mentioned is not protective in a beneficial sense; it deprives the immune system of the challenges it needs to mature properly. This lowering of immunity is more accurately described as immune dysregulation: the system becomes hyperactive against the wrong targets. …