The Housing Department will spend $68 million to add a single screw to windows in 53 housing estates to make them safer. This was among plans announced yesterday to reduce the risk of windows falling - as at least six more plummeted from buildings across the city. Yesterday's incidents brought to 25 the number of cases this month. One person was injured: the driver of a car struck by a window in Square Street, Central, at about 6pm. The window shattered the windscreen and the driver suffered cuts to his hand. The Housing Department will set up 20 technical teams to inspect aluminium windows at all estates. Letters urging tenants to pay extra care to aluminium windows will be sent to 680,000 households. The Buildings Department will also send letters to 1.3 million private households in the next two weeks to remind residents to pay more attention to the maintenance of aluminium windows. The department has also met private housing management companies to discuss details of possible seminars to educate residents about aluminium window frames. Director Wu Moon-hoi said the department and the Housing, Planning and Lands Bureau were also studying the possibility of introducing a compulsory inspection of aluminium window frames in private housing. The Housing Department's $68 million project will be carried out in 140,000 'Harmony-style' public flats built before 2000. It is expected to take nine months. Deputy Director of Housing (estate management) Lau Kai-hung said that until 2000 only two steel screws were used when installing aluminium windows. After that, a Housing Department guideline was issued requiring three. Mr Lau denied the department had been slow to react, despite recording 88 cases of windows falling off estate flats between 2000 and 2004. In the first six months this year, 14 cases were reported. '[Using two screws] met the requirement set by the Buildings Department at that time. The Buildings Department only drafted a new guideline detailing the three-screw requirement this March,' he said. Mr Lau promised window problems would be fixed within 48 hours of the department receiving a report. The Housing Society launched a Building Management and Maintenance Scheme on February 1. The free inspection programme is open to the public but priority is given to buildings over 20 years old and with a rateable value of $66,000 for urban flats and $50,000 for apartments in the New Territories. But the scheme does not include the cost of changing windows.