He is well beyond the retirement age, but Mr Chee Chat San still carries out his job with pride.

As a Changi Service Ambassador, Mr Chee turns up at the airport every Monday in his neatly-pressed uniform to give directions and offer help to travellers during his four-hour shifts.

He has been doing this for the last four years without pay - at least not in the monetary sense.

Mr Chee, 78, is part of RSVP Singapore, a non-profit organisation for senior volunteers.

The National Senior Volunteer Month (NSVM), a campaign by the organisation to raise awareness about senior volunteerism, will be launched officially by President Tony Tan Keng Yam tomorrow at Toa Payoh HDB Hub.

In May, The Straits Times reported that volunteerism among people aged 65 and above slid from 17 per cent in 2012 to 9 per cent last year, according to the latest Individual Giving Survey by the National Volunteer and Philanthropy Centre (NVPC).

This is a trend that Mr Edmund Song, executive director of RSVP Singapore, hopes to improve.

He says: "We hope to show that senior volunteerism is not an onerous task and to provide opportunities for seniors to volunteer in the private and social services sectors."

Mr Song believes that senior volunteerism is beneficial to a greying population here. He adds: "Longevity can be celebrated when the person living longer is leading a fulfilling life. We want to make that happen by helping seniors to continue giving back to society."

This is the impetus that drives Mr Chee, one of the 300 regular senior volunteers at RSVP Singapore.

He says: "Every day is a bonus, and I make full use of it to repay society and do a little something for my fellow human beings."

Besides helping out at the airport, the retired radio surveyor has been volunteering as a guide in the emergency department at Khoo Teck Puat Hospital (KTPH) every Tuesday for the last three years.

There, Mr Chee, who speaks English, Mandarin and some Chinese dialects, helps patients with registration and, sometimes, translation.

Mr Chee, who is a divorcee, works as a church caretaker and lives on the grounds of the church in Upper Serangoon Road.

His altruism goes beyond our shores. Last month, the genial man spent a week volunteering at an orphanage near Manila run by a Singaporean.

He took with him about $250 worth of toys, stationery and musical instruments, which he bought from a thrift store, for the children in the Philippines.

He did the same for an orphanage in Myanmar last year.

"I'm not rich but I can spend less, save up and help others," says Mr Chee, who was RSVP Singapore's Volunteer of the Year in 2014.

His gestures are not always appreciated, though. He sometimes gets brushed aside rudely by travellers who mistake him for a taxi tout at the airport.

"I don't get offended. It's our duty and job to help afterall," he says.

" No one will hire me at my age. But I think I can still be of value to others, so I'll continue volunteering as long as I can walk."