Answer:
Volunteering is a perfect opportunity to gain certain work experience which can significantly influence one's future. When we help others, it increases our self-esteem and makes us satisfied. Whether one is going to volunteer in his/her own community or in a national group depends on his/her preferences.
It could be argued that it is better to volunteer for an environmental group in your community. First of all, volunteering in one's own community is time-saving, because you do not have to travel to work every day. A person has more free time for the other activities that he/she wants to participate in. Moreover, it is quite fulfilling to do something useful for your own community and since you spend a lot of your time there, you are likely to notice the changes in the environment and results of your work.