The air we breathe

It's a grim fact that for more than a decade Hong Kong's air quality has been getting worse. The great leap forward in the Chinese economy may be good for high rollers, but for those down on the street, it has meant a noticeable decline in air quality amid public concern that not enough is being done.

Like most of society's ills, solving air quality problems is not straightforward. The finger is commonly pointed at the power plants and factories of Shenzhen and Guangzhou, but there are also causes closer to home that are to blame, as well as factors we can't control, such as the weather.

Hong Kong is one of the most densely populated cities in the world. Where you live, how densely packed the buildings are around you and how they are built will all affect the quality of the air you breathe.

Our narrow roads and tall wall-like buildings create what is called the 'street canyon effect', in which pollution high in the air is trapped in the spaces between buildings.

When this is combined with vehicle emissions from the street, the air pollution near the ground becomes that much greater than that in the air above the buildings.

Given that we can't all relocate to the New Territories and there's a limit to how much we can affect the air quality outside, many people are asking what they can to do to improve the air they and their family breathe at home.

Top of the list would be to stop smoking indoors. Other considerations are to clean air conditioners and their filters each week, refrain from burning incense or make sure your home is well-ventilated when you do, and try to limit smoky cooking.

In terms of air quality, kitchens tend to be the most polluted room of the house, but as many flats are open-plan, it can be hard to limit the airflow.

The answer could be to install an air purifier in your home.

Wong King-chung, manager of Fabri-Technic Engineering and Trading Company, which sells the IQAir air purifying machine, used in more than 95 per cent of Hong Kong hospitals, offers a free home assessment, which is a useful starting point.

'Most people don't understand what air pollution levels are inside their home,' Mr Wong says. 'They don't know how high the carbon dioxide level is or what the particulate level is.'

Mr Wong says customers should check the machine they buy does what the salesperson says it does, as there are few regulations to ensure that purifiers really work.

Installing the IQAir machine can reassure people that while at home, the airborne pollutants breathed aren't at the same choking level as those on the street.