Residents living on the third storey of a Toa Payoh block thought things would get better after their hoarder neighbour died last month.
But the stench from his flat, which they have put up with for more than 10 years, has remained.
This is because the mess in his flat cannot be cleaned up until his next-of-kin can be located.
The dead man, who was in his 50s, lived alone and mostly kept to himself.
A concerned neighbour called the police after noticing that he had not been seen for a week.
His decomposing body was later discovered in his squalid three-room flat at Block 195 Kim Keat Avenue on Nov 18. Also found in the flat were several cats.
When The New Paper went there last Friday afternoon, there was a new lock on the gate of the flat but the door was ajar.
Nearly a month after the man's death, the stink remains. Cockroaches and flies can constantly be seen around the flat.
Housewife Sarah Osnay, 56, who lives four units away from the flat, said she uses up four cans of insecticide a month, spraying the corridor outside her flat every day.
She said: "It's much worse at night because the wind blows the smell in the direction of our flat.
"(At night), the cockroaches come out of the flat and the cleaner would have to sweep them away the next morning. Sometimes my husband wakes up in the middle of the night to spray insecticide."
Another housewife, Madam Siti Hasan, 32, who lives next to the unit, keeps her door and windows shut at all times.
The mother of two children, aged five and seven, is distressed by the pests.
She said: "We've been putting up with the smell for eight years since we moved in, but the smell gets worse every day.
"Our family is suffering. My kids have sensitive nose problems because the air-con has to be turned on very often."
Last Wednesday, three volunteers from the Cat Welfare Society (CWS) were the first people to enter the flat since the body was removed last month.
They had received an e-mail from a neighbour alerting them to the cats in the unit last Monday.
One of the CWS volunteers, Ms Elaine Yap, 33, said they spent a harrowing two hours rescuing seven cats in the flat.
The volunteers had to clear bags of trash before they could even enter the flat.
Ms Yap said: "We brought masks and gloves, and tied plastic bags around our shoes.
"We had to step outside to take a break several times because of the smell. We felt nauseous and had headaches."
The CWS is now taking care of the cats, which were malnourished and had sores on their bodies.
When contacted, a Bishan-Toa Payoh Town Council spokesman said: "Tenancy matters come under the purview of HDB. The town council manages the common areas of the estate."