Diksha, you bring up an interesting point. Did you find scientific evidence on this? I’d be interested to read the articles. From what I’ve read, running with a mask does increase the amount of CO2 you inhale (from the air you exhale), but not in dangerous amounts as the CO2 particles still go through the mask and out the sides, and it does not outweigh the amount of O2 you breathe in. Here’s an example of an article I found: https://hartfordhealthcare.org/about-us/news-press/news-detail?articleid=26712&publicId=395

I think the idea of not running too close to people is nice in theory but hard to maintain in urban or suburban areas, especially in summertime when many people are out and about. Thus, I would still recommend wearing a mask with the added caveat that if no one is around you, you can pull it down, but as soon as you see someone else in sight, pull it up. :)