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Helene Franchineau

A father who feared pollution was damaging the health of his two young children and mistrusted the official statistics has built a free iPhone application to monitor air quality.

Tech-savvy entrepreneur Andrew Leyden arrived in Hong Kong two years ago and like many, wondered how bad the pollution actually was. 

The 45-year-old American, who has two sons Connor, five, and Parker, three, said: 'I built this app out of curiosity. I wanted to know whether it was safe for my kids to go play outside.

'I looked at Hong Kong's Air Pollution Index (API), but I did not really know what it meant. That's when I decided to do a little maths.'

Leyden started looking seriously into Hong Kong's API a year ago, but only started building the app over Christmas. He asked a friend for help when it came to the serious coding.

The Hong Kong Air Pollution app was submitted to Apple on February 19 and a week later it was ready to download from the online App store. Despite a quiet launch, it has already had about 1,000 downloads.

The application locates the user's position and matches it with one of Hong Kong's 14 monitoring stations. 

The user then chooses which pollution standards to measure the readings by - those set by Hong Kong, France, Australia, the US, Britain or the World Health Organisation. Each monitoring station is shown with a coloured flag according to the overall seriousness of the pollution there (red for high, green for good etc).

If the user is located in Causeway Bay, for instance, there will be a small paragraph on the official recommendation from the Environmental Protection Department and the current reading of each pollutant that is part of the API (nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide and respiratory suspended particulate, known as PM10).

For instance, on Friday at 11am, Causeway Bay's pollution level was considered 'high' by local standards and the EPD's message read: 'Acute health effects are not expected but chronic effects may be observed if one is persistently exposed to such levels.' 

Under the Australian readings, it read: 'For people unusually sensitive to air pollution, plan strenuous outdoor activities when air quality is better.' 

Pollution levels can be considered mediocre for Hong Kong but good in the US, or hazardous in Australia. 

On Wednesday March 14, the Causeway Bay station was flagged red according to Hong Kong standards, with an overall reading of 91 ('high'). It was 'above the maximum limit' for the World Health Organ-isation (with a reading of 161); in Australian terms the air quality rated 'very poor' (again with a 161 reading).

'It was overall a very educational experience for me,' said Leyden. 'It is eye-opening to see the differences between countries.' 

For example, under Hong Kong's current Air Quality Objectives, the standard for PM10 is 180 micrograms per cubic metre per day. For the World Health Organisation it is 50. 

Leyden, who lives in Mid-Levels, made extensive use of social media, such as Twitter and Google Plus, to get help from Hongkongers when it came to fine-tuning the app. 

'People were very responsive,' he said. 'Some parents would come up and tell me that they had always wondered whether they should let their children go out and play,' he said. 

'Sometimes, that answer is: no, they should not.'

Air quality groups, including the Clean Air Network (CAN), helped him on the pollution standards. 

Yuling Jia, education and research manager for CAN, said the air pollution app was the first measuring the pollution level based on different countries' readings. 

She accused the government of withholding information on pollution levels. But the EPD said the API was updated on an hourly basis on its website and people could also access it by telephone at 2827 8541. 

Leyden would like to see more people start monitoring their environment to get a broader picture, instead of only seeing what is going on in the busiest parts of the city. 

The EPD said there was no plan to set up an air quality monitoring station on the south side of Hong Kong island, or in other areas where there is less development, as 'the air quality should be better'.

An update of the app is to be released soon and Leyden is meanwhile preparing an Android version.

Leyden says he uses his application more often than the weather forecast. 'In the end, pollution is the key thing we consider to decide how long we are going to stay in Hong Kong,' he said.

20% 

Pollution levels at three roadside monitor stations were 'very high' for this amount of time last year and were 10 times worse than in 2005



App shows you how bad the air really is