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10 November 2007

Some Clean Air Ideas for HK Email 2 Plan B

From: Robert HO
Sent: Tuesday, October 23, 2007 3:35 PM
Subject: Idea: To Bubble Polluted Air Through Liquid Tank To Emerge Cleaner


Office of the Chief Executive
Hong Kong Special Administrative Region
People's Republic of China

5/F, Central Government Offices, Main Wing,
Lower Albert Road,
Hong Kong
Telephone : (852) 2878 3300
Fax : (852) 2509 0577
E-mail :

Dear Mr Donald Tsang,

1. I have previously emailed you on 18 Jun 05 on my idea of Govt By
Referendum [attached].

2. I have also emailed you on 12 Oct 07 on my idea of using jet engines to
blow away the bad air from the worst polluted and most peopled parts of
Hongkong. In this regard, I have had a short exchange of emails with your
Air Science Group but they did not consider the idea "workable" [attached].

3. Today, I would like to interest you in my Plan B, which also aims to
clear the air over Hongkong. It is an alternative to Plan A or it can be
used together with Plan A for even greater effect.

4. Background to the strategy in Plans A and B: When there is air
pollution over a city such as Hongkong or Beijing, you can ameliorate the
air pollution 2 ways -- either you legislate to PREVENT air pollution or
you try to CURE the air After it has been polluted. To PREVENT air
pollution, you can legislate to force polluting factories to relocate far
away or even to another country or province. Also, to PREVENT air
pollution, you can legislate cleaner exhaust from all or most vehicles. Or
you can ban all or some vehicles from designated areas of high pollution.
All these PREVENTION measures carry a very high economic cost and even a
social and political cost. I will not dwell on these PREVENTION measures
as I am sure you have already done them or are trying to do them.

5. Instead, I have chosen to try the CURE strategy. That is, to clean the
air after it has already been polluted. I know that much of Hongkong's bad
air is NOT created in Hongkong but wafts over from the Pearl River Delta.
So there is little you can do about PREVENTION in the Delta. Which means
you can only try the CURE. My Plans A and B are both CUREs.

6. The jet engine idea is direct and quick. It involves only a small
number of people and depts. The dept in charge simply buys an engine or
borrows 1, on its own. Tests it and monitors and studies the results. If
successful, then this dept would simply get down to the business of
implementing it in the most polluted areas WITH THE MOST PEOPLE. All done
by the Hongkong Govt with little need to involve too many people. Thus, it
is simple and everything is done with only a few layers of people and

7. For Plan B, which is to clean the air after it has been polluted, we
would need to involve slightly more people and companies; we would need to
[probably] legislate and to train and equip Govt officers to monitor all
the apparatus through regular checks, mostly to ensure effectiveness.

8. It is also a simple idea. Basically, it is to bubble the polluted air
through a LIQUID so that the air that emerges from the TANK is cleaner [not
necessarily completely clean]. Depending on the liquid and the size of the
bubbles [as tiny as possible] and the height through which the bubbles are
bubbled up [the tank to be as tall as possible] to emerge as cleaner air,
most of the particles and chemicals that make up bad air would be either
dissolved, trapped or removed by the Liquid, leaving much cleaner air which
is then pumped towards the street level, fitter for human breathing than
the bad air that goes into the tank.

9. So, to put it in words, you would need a small electric motor, which is
very cheap nowadays, to pump air [polluted air] into a tank of Liquid,
spraying the air into millions of tiny bubbles, the tinier the better, at
the bottom of the Liquid, to allow these millions of tiny bubbles to bubble
UP to the top of the Liquid, then emerge through another pipe or flexible
rubber hose at the top of the tank into the open air, preferably piped
towards the side of the rooftop so that this cleaner air, weighed down by
the moisture picked up from the liquid in the tank, will drift downwards to
street level.

10. So, to put it in a word diagram, the whole apparatus consists of the
electric motor, which pumps air through a fixed or flexible rubber hose,
the hose ending at the bottom of the liquid, where the air is sprayed into
millions of tiny air bubbles. These air bubbles will then float up to the
top of the liquid, in the process, dissolving some of the pollutant
chemicals and trapping some of the polluting particles or particulate
matter, to emerge at the top of the tank above the liquid surface, then
continue by pipe or flexible hose to the side of the rooftop so that the
cleaner air can be discharged downwards towards the street level, this
gravity-assisted downward air flow helped by the moisture the bubble-air
picked up through the bubbling process in the tank. You may even add an
air filter at the air outlet part of the system to further remove
particulate matter although changing the air filter will be quite a bit of
work, depending on how bad the air is and how tiny the filter holes.

11. This whole apparatus need not be big. The motor is small. The hoses
small and flexible, so easy to run along the floor to the tank and beyond.
The tank itself needs to be tall but not wide, so it will take up a minimum
footprint. That's all. [It would be better if the air intake hose is far
away from the air outlet hose so that we draw the worst polluted air --
possibly even from a dangling hose midway down the building; while the air
outlet hose should preferably dangle to be as near street level as possible
to best benefit those at ground level].

12. What Liquids would do the best job of dissolving the harmful chemicals
and trap the particles? Here, I don't know. Your team will have to
experiment with different Liquids. If water is used, then changing the
water is as simple as changing the water in an ornamental fish tank. The
water can simply be drained away onto the rooftop like rainwater and there
will be no pollution downstream of your roof drainage system. If seawater
is used, the seawater may corrode some metal pipes but that is not a big
problem if the system is flushed with tap water afterwards. If tap water
is used but with a simple household chemical like detergent added, it will
also not be very polluting since detergents are routinely flushed away
through the systems every day. I would suggest that your experiments begin
with tap water with added household chemicals like detergents, salt
[seawater], dishwashing liquids, etc, since these are the easiest and
cheapest to buy and put into the tank. Specialty chemicals may also be
used but beware of causing pollution when these liquid-chemicals are
flushed away -- probably not more than once a year].

13. After your experiments have confirmed which liquid solutions work best
in cleaning the air and which do the least harm to the environment and
sewer systems, then it will be time to proceed to the next step. Which is
to map out which rooftops need to install this air cleaning system. I
presume that your depts already know which areas are worst affected by air
pollution and which of these have the most people, so you will have to draw
up a list of rooftops [and their building owners] to force them to install
such a system at their expense [very cheap, actually, less than 1 month's
rent for 1 small office]. Politically, you will need to organise the mass
media to help in your "Clear The Air" Campaign. After you have identified
all the building owners and their rooftops for such installations, you will
need to interest about a few dozen companies to build prototypes for sale
to these building owners for installation on their rooftops, as mandated by
the Hongkong Govt. Green groups and environmental organisations should be
roped into this effort. They will not refuse because they have been
agitating for years and this time, when the Hongkong Govt presents them a
real opportunity to do something about it, they will gladly join in the
cause and maybe throw in a few ideas as well. Thus, the Hongkong Govt will
be seen as DOING SOMETHING about the problem. Which should help its image
and bolster its reputation. If this works, the expertise gained can then
quickly be brought to Beijing in time to clean the air there for the
Olympics in August 2008.

14. Thus, administratively, first, experiment to test the feasibility of
the idea. A Proof of Concept test. Test how big the whole apparatus must
be, how long it must run -- probably it has to keep running 24/7, I would
imagine -- the airflow though the system and how much cleaner the air is
that emerges.

15. Then, identify all the building owners who must install such a system.
This number will be the total size of the market for such systems. The
bigger the market, the more eager will be the companies to build good,
working systems to sell to them.

16. Privately, the Hongkong Govt would share the results and data from its
initial experiments and welcome companies to develop better, permanent
systems. When these companies are ready with their systems, then notify
all the building owners already identified to install such systems to
contact these companies to buy their systems. A list of such companies,
and their systems, should be made available to all the affected building

17. In your publicity programme, emphasise that this "Clear the Air"
campaign is not only for the good of the people on the streets, but also in
the entire vicinity of such installations. That is, a building owner who
installs a good and effective system is not only cleaning the air for
Hongkongers in general, but also the air in HIS vicinity, which appeals to
the self-interest of all people and therefore more effective. Thus, there
is a patriotic element or social good element in this programme. This
alone, should be a big plus for the Hongkong Govt. Even those building
owners or home owners not identified for compulsory installations can be
encouraged to install such a system, hence the importance of having several
models of such systems, from small to large, industrial sizes.

18. You may need to legislate or pass new by-laws to require identified
building owners to install and maintain such systems. Then, you only need
inspectors to check on such installations once in a while, a routine
procedure. It will not be a lot of work. These inspections would need to
test the effectiveness of such installations, such as the air throughput,
the quality of air before and after passing through the installation, etc.
Plus general tests of the air pollution over these selected areas to
determine how effective is the overall impact.

19. As with all rooftop installations, care will have to be taken to
ensure stability during typhoons and strong winds and rain. The liquid
should not attract mosquito breeding and should not be harmful. The
emerged air should also not smell bad or too distinctly obvious since some
people may be sensitive or may not like strong scents.

20. There may be a need to install multiple systems if 1 system is not
enough. This is probably preferable to installing a huge, industrial size
installation. Several smaller systems would be easier to manage, maintain
and install. Since the rooftops are big, several systems are not a
problem. The height of buildings is also not much of a problem in this
Plan B because the air intake hose and the air outlet hose can be dangled
right down to the very bottom of the buildng if required. So the air can
literally be drawn from the streets from among the vehicular pollution and
similarly, the air outlet can also reach down to the street to expel
cleaner air.

Looking forward to cleaner air when I next visit Hongkong,
Robert HO
28 Bukit Batok Street 52
#20-03 Guilin View
Singapore 659248
Tel: [65] 68989553
HP: [65] 90127417
23 Oct 07 1534


Major Air Pollutants in Hong Kong

Sulphur Dioxide (SO2) SOLUBLE IN WATER
Sulphur dioxide is a colourless, reactive gas that is odourless at low concentrations but has a pungent smell at very high concentrations. It is emitted primarily during the combustion of fossil fuels and the processing of sulphur-containing ores. The major sources of sulphur dioxide are fossil fuel-burning power plants, (generating electricity) and industrial boilers. Another source of sulphur dioxide is vehicular exhaust emissions.

The many chemical species of the oxides of nitrogen are collectively termed as nitrogen oxides (NOx). This group of gases usually enters the air as a result of combustion processes which involve high temperatures, such as those produced by power plants and vehicular engines.

Nitric oxide is the main NOx emitted during combustion and it can be converted into nitrogen dioxide.

Nitrogen dioxide (NO2) INSOLUBLE IN WATER
Nitrogen dioxide is a corrosive and highly oxidising light brown gas which has a characteristic pungent smell at high concentrations. It is the reaction of nitrogen dioxide with reactive organic substances, such as Volatile Organic Compounds (VOCs), in the presence of sunlight that produces ozone (see information on 'Ozone and Photochemical Oxidants)'. Nitrogen dioxide is, therefore, an important part of urban haze or photochemical smog.

Carbon Monoxide (CO) is a colourless, odourless and tasteless gas which is a by-product from the incomplete combustion of any fuel which contains carbon. Industrial processes contribute to CO pollution concentrations, but the principle source of CO in most urban areas, such as Hong Kong, is the automobile.

Ozone and Photochemical Oxidants OZONE SOLUBLE IN WATER, VERY REACTIVE
Ozone is not a pollutant directly emitted into the air from particular activities characteristic of urban or industrial areas, and can, therefore, be referred to as a secondary pollutant. Ozone and other photochemical oxidants (such as peroxyacyl nitrates and aldehydes) are formed by the action of ultra-violet (UV) light from the sun on nitrogen oxides (a process called photolysis). Its production and concentration is dependent on the presence of primary pollutants as well as ultra-violet light. In the presence of volatile organic compounds, high concentrations of ozone are formed.

This type of pollution first gained attention during the 1940's as Los Angeles smog. Now this smog is described in terms of its photochemical oxidant composition, which includes ozone and is termed 'photochemical smog'.

Respirable Suspended Particulates
RSP are the proportion of total suspended particulates with a size smaller than 10 micrometres and they have the ability to penetrate deeply into the lungs. Depending on their source and the existing meteorological conditions, RSP can be made up of a number of different constituents.

Particulates constituents
There are a number of chemicals that may form part of RSP. Two important constituents are lead and aromatic hydrocarbons.

Health Effects of Air Pollutants

Health Effects of Sulphur Dioxide
Exposure to elevated level of sulphur dioxide can cause impairment of respiratory function, aggravation of existing respiratory disease (especially bronchitis) and cardiovascular disease. In sensitive individuals, the lung function changes may be accompanied by perceptible symptoms such as wheezing, shortness of breath, and coughing. Sulphur dioxide may also lead to increased mortality, especially if elevated levels of suspended particles are also present. Major subgroups of the population that are most sensitive to sulphur dioxide include asthmatics and individuals with cardiovascular disease or chronic lung disease (such as bronchitis or emphysema) as well as children and the elderly.

Health Effects of Nitrogen Dioxide (NO2)
Nitrogen dioxide (NO2) can irritate the lungs and lower resistance to respiratory infection such as influenza. Individuals with respiratory problems, such as asthma, are more susceptible to the effects. In young children, nitrogen dioxide may also impair lung development. Studies suggest that chronic exposure to nitrogen dioxide may lead to structural changes in the lungs, however, specific levels and exposure duration likely to cause such effects have not yet been determined.

Health Effects of Carbon Monoxide
Inhaled CO enters the blood stream and binds preferentially to haemoglobin (the substance that carries oxygen to the cells), thereby replacing oxygen. It results in reducing the amount of oxygen which is delivered to body organs and tissues. The percentage of haemoglobin inactivated by CO depends on the amount of air breathed in, the concentration of CO in air and the duration of exposure. In a healthy person, elevated CO concentration exposure is associated with visual impairment, reduced work capacity, reduced mental function and poor learning ability. Persons suffering from heart and circulatory problems, fetuses, young infants, pregnant women and elderly people are likely to be more susceptible to the effects of CO.

Health Effects of Photochemical Oxidants
Ozone toxicity occurs in a continuum in which higher concentrations, longer exposure duration's and greater activity levels during exposure cause greater effects. Ozone has the greatest impact on the respiratory system, where it irritates the mucous membranes of the nose, throat and airways. Symptoms associated with exposure include cough, chest pain, and throat and eye irritation. Ozone can also increase susceptibility to respiratory infection. Acute adverse effects may impair normal functioning of the lungs and induce respiratory inflammation. Healthy individuals who exercise heavily for brief periods (1 to 2 hours) may experience respiratory symptoms at levels exceeding the Hong Kong Air Quality Objective of 240 microgrammes per cubic metre. They may also experience these symptoms at a lower concentration for longer exposure (6 to 8 hours) during moderate exercise. Individuals with sensitive respiratory systems (such as with asthma or respiratory disease) are more susceptible to the effects of ozone.

Health Effects of Total and Respirable Suspended Particulates
The health consequences of atmospheric suspended particulates depend on their ability to penetrate and deposit in the respiratory system. The respirable suspended particulates (RSP), i.e., particles with a diameter of 10 micrometres or less, which are able to reach and deposit deep in the lung, are most likely to be responsible for adverse health effects. The observed human health effects of RSP include breathing and respiratory symptoms (such as shortness of breath, coughing and wheezing), aggravation of existing respiratory disease and damage to lung tissues. Groups that appear to be most sensitive to the effects of RSP include individuals with chronic lung and heart disease, individuals with influenza, asthma, elderly people and children.

Health Effects of Lead
Lead is a toxic heavy metal which can be found in total or respirable suspended particulates. Lead particles from vehicular exhausts which are of a size smaller than 10 micrometres can affect both adults and children, but small children (and foetuses) are at greatest risk because of their smaller size, breathing patterns and the metabolism of lead in their bodies. The effects of lead exposure include damage to the nervous system, red blood cells, kidneys and potential increases in high blood pressure. Other health effects may result in decreased co-ordination and mental abilities. The effects of lead exposure can be treated and reversed, providing treatment is timely and lasts the entire course of therapy. If no treatment is given, permanent brain damage can result.

(Source: EPD, HKSAR Gov't)

RH 19 Nov 2010:

1. Today, it is time to revisit an old idea of 23 Oct 2007. Generally, it is good never to discard an idea completely but to revisit it now and then to see if various factors such as technical feasibility, price, social and political pressures, worsening conditions or the opposite -- improved conditions, changes in legislation, international practices, publicity and awareness, new inventions and product developments, etc, have so changed the factors leading to the earlier rejection of the idea, which may by now, due to the changed factors, make the idea now feasible when it was not so before. The idea of 23 Oct 2007 is here:

2. Just doing a cursory search on typing the search term "air purifiers", I found my idea already manufactured in the form of a little battery-operated system requiring only 3 AAA batteries:

3. In total, there are 9,839 results for "air purifiers" of which the air purifier in para 2 above is just only 1 example, which may or may not work as well as the others. It is beyond my effort to study all these thousands of air purifiers, some of which are powerful enough to clean the air in an entire home while others clean the air in just 1 room, or around a desktop, in the case of desktop air purifiers. The methods used vary from HEPA [] filters to eletrostatic methods and even ionisation and ozonisation. Some trap particles as small as 1 micron, which already makes the air very clean. HEPA filters remove at least 99.97% of airborne particles as small as 0.3 microns in diameter. Some air purifiers require practically no maintenance while others need a cleaning or change of filter now and then.

4. The below is a good but brief and incomplete discussion on air purifiers but discussing only the effectiveness and drawbacks for a typical American home, which is very, very, different from what we are trying to achieve, which is to reduce air pollution in a typical city like Hongkong or Beijing. But do read this anyway:

5. Another viewpoint to read, but again, from an American-home point of view, which is different from what we are trying to do. The article is obviously a sales push for the more expensive air purifiers although this store also sells air purifiers below US$50. Here is the price range of air purifiers carried by this US store, but note that if you buy from China, it will cost probably at least 50% less:
Air Purifiers Under $50,
Air Purifiers $50 to $100,
Air Purifiers $100 to $200,
Air Purifiers $200 to $300,
Air Purifiers $300 to $400,
Air Purifiers $400 to $500,
Air Purifiers $500 to $600,
Air Purifiers over $600.
Article at:

6. Since, in the intervening years from 23 Oct 2007 to now, so many companies have designed and are making air purifiers, there has never been a better time to revisit my idea, only this time, instead of a DIY water-filtration tank on the rooftop of every block, we can now subsidise the purchase of approved air purifiers for every Hongkong or Beijing home. If we can get 70% of all homes in a city affected by air pollution to use air purifiers, not only will these homes [extend this subsidy to offices, too] enjoy cleaner air, but the cleaned air will also leak out of the homes into the air in the city, thus cleaning the air in the city as well. It is a numbers game, meaning the more air purifiers a city is operating, the cleaner the city air will be, since no room in a home or a home vs the outside air, is hermetically sealed, so, with the air constantly intermingling and leaking to and from the home to the outside, by cleaning the air inside all homes, we will also clean the air in the city, too.

7. Thus, if enough homes buy an air purifier or even 2 or 3 or 4, depending on the budget, number of rooms, the needs of the home, the govt publicity campaign, public education and most importantly, the amount of govt subsidy, the air pollution in any city can be reduced. This works best for dense cities with mostly high-rise blocks, and works less well in cities that are spread out, with mostly standalone houses.

8. An additional benefit is that air purifiers also clean out or filter out germs like bird flu germs and other harmful viruses and bacteria. So, having air purifiers in 70% of all homes in a city can reduce the spread of bird flu and other germs. The healthcare costs savings from this alone can pay for the entire monies spent for the subsidies although it is hard to estimate how much healthcare costs savings you have made from a bird flu epidemic that did not happen, that is, that has been prevented by air purifiers!

9. What govts like the Hongkong govt can do is to quickly test and evaluate all the purifiers offered on or submitted by manufacturers hoping to have their models approved -- which can lead to huge sales since Hongkong alone has >2.2m households. If this mass purchase and use of air purifiers is successful, the far bigger world market will be a seller's fantasy come true. If the idea works, further research & development, product development and better models, will really take off.

10. Note that, speaking generally, with cities becoming more and more crowded, with people jostling elbow to elbow in public transport, shops, malls, public places, offices, cinemas, practically everywhere, this puts everyone at risk from everyone else, whether the other person is carrying a flu germ or smoking a cigarette. This overcrowding cannot be prevented but we can reduce at least one of the effects of overcrowding, which is the bad air caused by Man's needs for polluting cars, buses, factories, etc. Since we cannot banish these sources of pollution, reducing the resultant pollution by a massive city-wide use of effective air purifiers is a good solution.

11. This means that not just homes, but offices, cinemas, shopping malls, govt offices, etc, should all operate air purifiers, only bigger and better ones, since these have more money than most homes, as well as operating bigger premises. Again, some subsidy will help the adoption. Maybe given as tax incentives, grants, co-pay schemes, etc. To encourage widespread adoption, all those public spaces operators will be allowed to display a decal or poster proclaiming "We're helping to clear the air" or something like that. Thus, these operators will be able to publicise their civic-mindedness and at the same time, inform their customers and patrons that the air within these premises are being cleaned for their better comfort and health.

12. The Hongkong govt need not be seen to be fully behind this idea, if it does not want to, in case the idea flops. It can encourage representations, petitions, feedback from the Green Groups in Hongkong. Listen to their representations, then 'agree' to subsidise the mass purchases of approved air purifiers. The testing and evaluation of the air purifiers can even be done by the Green Groups, who can outsource it to any local or international expert organisations. So, the Hongkong govt need not be seen to be fully backing the idea, if it does not want to.

13. As to how much subsidy to give, this is entirely an executive decision, balancing the possible gain in reduced air pollution vs the costs, vs alternative uses of the money foregone. Billionaires and rich companies may also want to help fund these purchases, meaning that in the end, it may cost the Hongkong govt very little, maybe no cost at all.

14. There is another salutary effect of this idea, which is that air pollution becomes not just a problem for the govt to solve, but that every household can do something on its own. This is an important civic development. That every household can help reduce air pollution, starting from its own home. For this kind of civic development in citizens, this may be the most important effect of the air purifiers in the end. Good Luck and Success!

15. Previous ideas:
Some Clean Air Ideas for HK Email 1 Plan A (1)
Some Clean Air Ideas for HK Email 2 Plan B (1)
Some Clean Air Ideas for HK Email 3 Plan C (1)
Some Clean Air Ideas for HK Email 4 Plan D (1)

[[[[[[[[[[ My wife, an accountant now a manager in an MNC drawing a 5-figure salary, can now confirm that I write the Truth in all these. ]]]]]]]]]]