Changes to atmosphere with gas release?

[deleted-564347]

Assuming normal atmospheric conditions at sea level, if you were to release a gaseous product, how would it impact the makeup of the atmosphere?

Would it displace the oxygen and nitrogen percentages equally, or would it displace more or less of one or the other?

Example: you have a methane gas release into the atmosphere. How would that release impact the readings if you were to sample the atmosphere?

Thanks in Advance!

[MadelineB]

The Science Buddies forums are for students in grades K-12 who are doing science projects. Your profile shows that you registered as an adult. There are other websites on the internet where your questions would be more appropriate. Thank you.