If you want to refer to trash or waste in Spanish, there are a few more polite ways to phrase it. Instead of using 'garbage', you can say 'às desechos' (the garbage) or 'ôrganos' (waste). Alternatively, you could use 'Échos a tirar' (things to throw away), Échos para tirar (Things to get rid of), o simplemente decir 'dejar caer los desechos' or 'tirar los desechos'. Another way is saying 'lo que no necesito' (what I don't need). To say garbage in a more casual tone, you can use 'basura', but be careful with the connotation it might have. The phrase to throw away something politely could also be 'dejarme algo' or 'dejar caer algo'. To communicate your neighbor's concern, you could say that he thinks people should be more responsible with their trash and encourage others to do the same.