In the metropolitan cities of India, many children are suffering from allergy/asthma. What are the main causes of this problem? Give some symptoms of allergic reactions.

Explanation

### Step-by-Step Solution:

1. **Understanding the Problem**:
- In metropolitan cities of India, many children are suffering from allergies and asthma. Asthma is a type of allergy, specifically known as bronchial asthma, which involves inflammation of the bronchioles in the lungs.

2. **Definition of Allergy**:
- An allergy is a hypersensitive reaction of the immune system to foreign particles, which are recognized as antigens or allergens. When these allergens enter the body, the immune cells become hypersensitized and trigger an inflammatory response.

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