I refer to the report headlined, 'Procedure for dumping batteries rubbished' (South China Morning Post, May 3), which requires clarification. We responded immediately to the request from Mark Halliwell for information on disposal of batteries. We received his phone inquiry on April 21 and provided verbal and written information on the same day. We indicated that waste batteries are classified as chemical waste, waste producers should be registered, and they should employ licensed waste collectors for disposal at licensed facilities. The final disposal point is the Southeast New Territories (SENT) landfill. For lead-acid type batteries, the acid should be removed first and treated separately at a licensed facility such as the Chemical Waste Treatment Centre on Tsing Yi. Disposal of chemical waste at the SENT landfill is carried out in a controlled manner. There are complex physical, chemical and bacterial changes taking place during degradation of the large quantities of municipal waste in the landfill, that have the combined effect of eliminating most of the small quantities of toxic material released from the chemical waste. The landfill also has an impermeable lining system which retains and collects liquid leached from the waste. This leachate is treated to stringent standards before discharge. Of course, recycling of waste is preferable to disposal. However, the extent of recycling of batteries in the SAR is not well developed. We hope in the longer term to encourage the development of environmentally-acceptable recycling and also the manufacturing of more environmentally-friendly batteries that can be recharged and reused, last longer and contain less toxic components. The best method for individual car owners to dispose of their car batteries is to leave them with the car repair shops who provide new batteries. Most of these shops use proper disposal routes. R. C. ROOTHAM Principal Environmental Protection Officer Waste and Water Management for Director of Environmental Protection