PUBLISHED : Thursday, 24 January, 2002, 12:00am
UPDATED : Thursday, 24 January, 2002, 12:00am

IF YOU LIVE near a Caltex petrol station you may increasingly have noticed taxis pulling up to have that oval-shaped particulate filter on their exhausts removed and cleaned. They should be doing it every two days and public light buses (PLB) every day.

At least they should be if they are following the guidelines laid down by the Polytechnic University for the efficient operation of the particulate traps it devised and which are now being sold through the newly listed Eco-Tek Holdings, one of only two approved distributors of such devices and the clear market leader.

The PolyU's tests clearly showed that emission reductions quickly fell below the trap's rated 30 per cent if the cleaning schedule was any less frequent and that this would also introduce the risk of spontaneous soot regeneration. In other words, we would get the soot right back in our lungs.

It is all very clearly laid out. Bring the vehicle in, un-clip the back portion of the trap (probably best not done with bare fingers if the engine has not cooled), pull out the wire mesh, put in a bucket of cleaning solution, swish it about, take it out again, clip it back inside the trap (perhaps cooler now) and Bob's your uncle.

Nuisance though it may be to busy taxi or PLB drivers, we shall just have to assume they are all doing it right on schedule. I am not about to do a tally with every Caltex station every night. Are you?

But at least it is a simple device and a cheap one, too. It costs us only HK$1,300 for each installation (yes, we the taxpayers pick up the bill, not the fleet operators) - goodness knows what the price would have been if we had instead adopted some of the particulate traps mentioned in a 1998 study done for the Environmental Protection Department.

It is all very well that tests on these more sophisticated devices cited figures in the 80 per cent and even the 90 per cent range for particulate reduction but they would undoubtedly have cost a good deal more than HK$1,300 apiece. Which is more important?

However, there are questions to raise about this HK$1,300 figure. In a paper to the Legislative Council in May 2000 the Environment and Food Bureau said that the cost of the PolyU's trap including installation was 'around' HK$1,200.

Turn to a PolyU report in July 2000, however, and you read that 'the cost of the particulate trap depends on business factors, which cannot be assessed during the trial programme. Despite this, a rough indication is that, if mass produced, the direct cost is about HK$300 per trap.' So, how can the bureau tell Legco in May that the cost is HK$1,200 when the PolyU, which did the work, says in July that it doesn't know what it will be but estimates HK$300? This HK$300 figure seems to have been closest to the mark, by the way.

Eco-Tek, which now has the rights to the trap, reported HK$12.6 million in gross profits on turnover of HK$16.9 million for the nine months to July 31, 2001. This is a 74.8 per cent profit margin.

So, I am frankly puzzled when the Director of Environmental Protection, Robert Law, in a letter to the editor published on Tuesday ('Suggestions of sinister dealings are completely groundless') objects to my earlier criticism of this profit margin on the grounds that is the result of a 'normal transparent government tendering exercise'.

His department was involved with the development of this trap from the beginning and in fact helped fund its trials. It is all there in the document record - a HK$1,200 estimate to Legco but a HK$300 estimate from the PolyU and Eco-Tek now enjoys the difference.

Yes, Mr Law, I have my doubts about this tender and I think there are some legitimate questions to pose here.