A person shows strong unusual hypersensitive reaction when exposed to certain substance present in air.
Mention the term used for these substances.

Explanation

To answer the question regarding the term used for substances that cause strong unusual hypersensitive reactions in a person when exposed to them, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**: The question describes a person who shows a strong unusual hypersensitive reaction when exposed to certain substances in the air. This indicates that the immune system is reacting strongly to something that is typically harmless.

2. **Identifying the Condition**: The type of reaction described is known as an "allergic reaction." An allergic reaction is a hypersensitive response of the immune system to foreign substances.

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