{
    local %ENV = %ENV;
    
    ## make your additions (deletions, changes) here;
    $ENV{FOO} = 'BAR';

    my $pid = open my $pipe, '-|', '/path/to/the/executable', @args or die ...;

    sleep $someTime;

    kill KILL, $pid;
}
## the changes to %ENV are undone once you reach here