Polestar has had to divert the production of weekend newspaper magazine supplements to its other plants after the explosion at one of Greaves boiler houses, which caused two members of staff to be taken to hospital to be treated for shock.

Polestar Greaves commercial director John Stevenson said they received no physical injuries and were discharged after about an hour.

North Yorkshire Fire and Rescue Service and a team from Polestar are investigating the cause of the blast at the 200m2 building.

Around 300,000 copies of the Times Saturday magazine, which has a print run of 850,000, have to be produced at Polestar Varnicoat and bound by Polestar Purnell. Copies of the Times Sunday supplement and the Express Saturday magazine produced at Greaves are unaffected. All of the plants customers have been informed, however, that there may be more serious displacement of commercial work.

Polestar Greaves managing director Lindsay Atkinson said it was lucky that no one was seriously hurt. It will be a few days before we know what happened. The boiler room houses the main supply of heat, steam and gas for the company, all of which could be contributory factors.

A spokeswoman for North Yorkshire Fire and Rescue Service said two appliances were initially sent to the incident at 16.25, followed by another two and an Incident Response Unit equipped with airbags, thermal imaging, and specialist cutting equipment. A spokeswoman said the boiler house contained an amount of toluene and acid.

But a spokeswoman for Polestar said it was unlikely that toluene would have been in the boiler house, although that the company was keeping an open mind.

Two of Greaves three boilers are functioning and a temporary one will be brought in until permanent repairs are made. Greaves four gravure presses and its solvent recovery plant are operational. Around 98.5% of the solvent toluene used in Greaves printing inks is recovered.

(*) Polestar has concluded its acquisition of the e-commerce division of httprint, revealed in PrintWeek last week. Tim Smith, formerly European sales and marketing director of httprint, rejoins Polestar as director of a new category that encompasses the acquired operations, the groups existing software business, Whitefriars, and 4c, its print management arm.