I know, select * is not a good idea; It was just an example to get the point across. Well, anyway after checking the docs, I found out how to do it. With bind variable it actually improve performance bec. the sql sythax doesn't have to be reparse. Well here's how:

$sth_detections = $dbh->prepare("$QUERY2") || die $DBI::errstr;
for ...
my $city = $city[$i];
my $station = $station[$i]; 

$sth_detections->bind_param(":city", $city);
$sth_detections->bind_param(":station", $station);
$sth_detections->execute;
@row = $sth_detections->fetchrow;
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