He also tries to confuse correlation with causation by saying that cancer, mental illness and use of these bulbs have increased in line. Perhaps all three are linked to increasing urbanisation over the course of the study?

Dr Hanson accuses the lighting industry of obstructing public education on the health dangers, but then admits they are providing detailed clean-up and disposal instructions.

Finally, he wants access to "healthy, toxin-free incandescent lights", but every incandescent bulb I've bought had blobs of solder, that's lead-tin solder, on the base. Also, if he's powering his incandescent bulbs from a coal-powered power station, he might like to consider the mercury emitted by the power station.

I'm sorry, Dr Hanson, unless you've got some real, scientific data to back up your claims, your letter looks like an unjustified, Luddite attack against new technology.

I refer to the letter by David Lai ("Immigration boss should disclose goals", February 3), concerning his comments on the Immigration Department seeking funds for an upgrade of its checkpoint facilities.

Hong Kong is one on the most popular international trade and tourism hubs in the region, with heavy passenger traffic and visitor throughputs at its control points.

From 2007 to 2011, the number of visitors increased at an average annual rate of 10.76 per cent.

In 2012, visitor numbers further increased by 15.94 per cent to 48.615 million. Over the same five-year period, local resident throughput also recorded an average annual growth of 1.12 per cent.

In anticipation of further growth of passenger traffic at control points and to cope with the limits, including handling capacity, of the existing control point systems we need to implement a new control point system at an estimated cost of HK$912.2 million under our commitment to provide efficient and effective services at control points.

We secured support of our proposal of implementing a new control point system from the panel on security of the Legislative Council on December 4, and obtained approval of the funding request from Lecgo's Finance Committee on February 8.

The new system aims to maintain uninterrupted and quality clearance services to continual growth of passenger traffic in the coming years and to enable our introducing new immigration initiatives including self-service departure for visitors through e-channels.

Apart from integrating, upgrading or replacing the hardware and software of the existing control point systems, the project will also cover the upgrading of some 430 existing e-channels, and deploying more than 100 new e-channels at various control points, enhancing biometric authentication, automating business processes and upgrading system architecture to cater for future business needs and the commissioning of new control points.

Out of the provision, of HK$912.2 million, it is estimated that the acquisition of hardware, software and implementation services will incur a major proportion of expenditure.

The new system is scheduled to be implemented by phases from the end of 2015.

I hope that your correspondent finds this information helpful.

With the World Wildlife Foundation's Earth Hour City Challenge coming up, I perceive matters as "a given" when it comes to earth's future.

I'm convinced that earth's populace will eventually find the planet at the most crucial juncture - perhaps since the extinction of the dinosaurs - involving the entire quality of our existence.

Either we will make a 90-degree turn in one direction, favouring an absolute priority of economic and job growth, especially involving natural resources; or we turn 90 degrees in the opposite direction, resulting in a potential world with the emphasis on having only the necessities of life, safeguarding peace and against needless illness and suffering.

Perhaps I'm just too cynical, but from what I've observed from collective humanity's seriously flawed (to put it mildly) nature, we likely won't turn in the correct direction and in time.

To find an affordable house, a pressure group, to which legislative councillor Chan Yuen-han belongs, has suggested converting shipping containers into homes and placing them in empty spaces below flyovers ("Campaign to bridge housing gap", February 15).

The action is feasible. The tension of land supply could be reduced. Young people especially are hunting for affordable housing. Unfortunately for them, even subdivided units are unaffordable.

They could have their own little world in a converted shipping container beneath a flyover. The containers would have built-in toilets - much better than sharing a toilet in a subdivided unit. And the occupants would have only to open their front door to reach the street.

The only fly in the ointment is the noise problem - large, noisy trucks would wake people living inside the containers from their sweet dreams.

Even so, the government should consider the potential of the spaces to solve urgent accommodation problems.

I refer to the letter by Renata Lopez ("Discordant note struck in Mok interview", February 24), on cover piece on my daughter Karen Mok ("What Karen did next", January 27).

Please allow me to clarify a misunderstanding.

When Karen was studying in London, Lea Salonga was already starring in . Karen auditioned - not for the original cast - but only in 1991 for a place in the chorus.

She was successful, chosen to join the training class of this West End musical when the Hong Kong offer came and which she took. (We would have wanted her home anyway.)

Like a lot of people, in our minds Lea Salonga is "Miss Saigon", there is no other. In fact our entire family cheered for this Filipino singing sensation when she was selected from Asia for this lead role.

This particular interview was about Karen's new album; in other interviews she paid tribute to her present jazz album team, of course, and to those she had worked with over the years in Greater China and elsewhere.

Indeed, those who have met Karen, even for the first time, are impressed by her warmth, kindness, sincerity, positive attitude, immense generosity and respect for all - nature, animals and man.

I am writing in response to the article ('Tobacco tax hike can lead to reduction in number of smokers', February 18). I disagree with your correspondents and I am glad there was no increase in the tobacco tax in the budget.

Most smokers in Hong Kong are addicted to tobacco. Of these, a portion are poor and elderly. They will pay a lot for cigarettes, which are one of their few pleasures.

Our government has hiked tax on tobacco many times without a significant decrease in the number of smokers as a result. This shows such increases are an inefficient way to dissuade people from smoking, yet will increase the burden on poor, elderly smokers.

I believe our government should try to teach Hong Kong people not to smoke. It should increase the resources and facilities available to educate people about the bad effects of smoking.

At the same time, the administration should give more resources to our medical practitioners so that they can help smokers to quit the habit.

In short, a tobacco tax hike is not the best way to stop people from smoking. We must educate them instead of just imposing a higher tobacco tax.