Syngenta is located along Leeds Road, Huddersfield. As a large chemical factory they are regulated under legislation called Control Of Major Accident Hazards. They test their warning sirens annually and this year's test takes place on Monday 6 June between 10am and midday.

The siren is planned to be sounded at 11:00, and the usual cycle is 5 minutes on, 5 minutes off, then 30 seconds on again. If all is well that should be all you will hear. If they have any issues that require maintenance and then a further test, this is usually done on low volume. They reserve the right to test on full volume again if necessary.

During the 5 minutes and following 30 seconds that the siren is sounding, it is a wailing, air raid siren-like noise; and it will very much depend on the wind direction on the day as to which areas might hear it. Last year it was as far as Mirfield, the year before it went deep into the Holme valley.