What are the effects of `NO_x`

Explanation

### Step-by-Step Solution:

1. **Definition of NOx**:
- NOx refers to nitrogen oxides, which are a group of gases that include nitrogen dioxide (NO2) and nitric oxide (NO). These gases are primarily produced from vehicle emissions, industrial processes, and burning fossil fuels.

2. **Effects on Human Health**:
- **Respiratory Issues**: Breathing in NOx can lead to various respiratory problems. It can irritate the airways in the human respiratory system, leading to conditions such as asthma and bronchitis.
- **Reduced Lung Function**: Chronic exposure to NOx can result in long-term damage to lung function, making it difficult for individuals to breathe properly.
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