Even if they were affected by any measurable amount, the photons move so much faster than the air that it's an absolutely negligible difference incapable of being measured. It's like 1 trillion divided by 1 trillion and 1 equaling approximately 1. The outcome is unaffected by the extra 1. It's a non-factor. I'm trying to explain this for the future not-smart-people but I think I'm just making it much worse.