For CentOS and other Red Hat distros, add the umask setting to /etc/sysconfig/httpd and restart apache.
[root ~]$ echo "umask 002" >> /etc/sysconfig/httpd [root ~]$ service httpd restart
More info: Apache2 umask | MDLog:/sysadmin
For Debian and Ubuntu systems, you would similarly edit /etc/apache2/envvars.