Sorry answered my own question. Just a note this is only available in Kingston and Jakarta and it's not in previous versions.

if (hashGr.next()){
timestamp = hashGr.getValue('hash'); //get last calculated timestamp
var inProgress = new GlideDateTime();
var secondsBack = gs.getProperty("evt_mgmt.alert_rule_delay", "5");
var gt = new GlideTime(1000 * secondsBack);
inProgress.subtract(gt);
var openStates = ["Open", "Reopen", "Flapping"];
var recentAlerts = new GlideRecord('em_alert');
recentAlerts.addQuery('sys_updated_on', '>=', timestamp);
recentAlerts.addQuery('sys_updated_on', '<=', inProgress);
recentAlerts.addQuery('state', 'IN', openStates);
recentAlerts.query();

This is from the scheduled job so it is indeed global. If you want to make it more flexible you will have to do what I said but if it's for all sources then you should be set to use this.