Anxiety
You may breathe harder when you’re scared or worried. It’s usually not a big deal, but it can be serious if you already have lung problems like COPD. Sudden stress, like a car accident, could trigger an attack if you have asthma. Even if you’re otherwise healthy, anxiety might cause you to breathe fast enough to get lightheaded and pass out.
Carbon Monoxide
It’s a colorless, odorless gas that can come from furnaces, fireplaces, water heaters, dryers, and car fumes. If it isn’t sent out the right way, it can build up in the air, and you could breathe too much of it. That makes it hard for your red blood cells to send oxygen through your body. You may be short of breath, dizzy, confused, weak, and nauseated. Your vision could blur, and you could pass out. It could be life-threatening.