Coughing and throat/chest irritation: High levels of ozone can irritate your respiratory system. Generally, these types of mild symptoms only last for a few hours after you've been exposed to smog. However, ozone can continue to harm your lungs even after symptoms disappear.
Worsening asthma symptoms: If you suffer from asthma, being exposed to high levels of ozone from smog can trigger asthma attacks.
Difficulty breathing and lung damage: Because of ozone's effect on lung function, smog can make it feel difficult to breathe deeply, especially during exercise. Research has shown that ozone exposure can also damage the lining of your lungs.