Catherine Leung Lai-chu tears open an envelope and empties the coins inside onto a biscuit tin lid. After more than a decade of practice, she needs only seconds to identify the various currencies and put them into different tins on a table.
Leung, 60, has been a volunteer for Unicef's Change for Good programme since 1998, and is considered one of the 'seniors' in identifying currencies.
The programme appeals for donations on flights, encouraging travellers to give money they no longer need to Unicef. Eight airlines in the world help collect donations on their flights, among them Cathay Pacific.
The airline helped raise nearly HK$12 million last year, a record amount, and more than HK$100 million since the project was launched two decades ago.
The money is sorted by volunteers three times a week at the Unicef headquarters in Happy Valley.
Dozens of tins labelled with the names of different countries are spread out on a table with about 10 volunteers working at a time to sort out the money.
Sometimes when they come across a particularly big donation a big cheer goes up. Apart from money, the envelopes can also include other items such as sweets, buttons, gold coins and rings. Once they even found a Bible in a collection bag.