The council interviewed 1,105 subdivided flat tenants between April and October last year.

Some 16 percent of respondents said their health was "poor," while more than 95 percent logged a lower-than-average score in the mental health self-assessment.

The poll also found that members of single-parent families are more exposed to health risks, as they only average six hours of sleep a day. Only 16 percent of them had received health checks in the past three years.

Additionally, 16 percent of them ate canned foods and instant noodles for lunch and dinner for more than five days per week, while 60 percent did not consume vegetables daily.

The council cited the case of 59-year-old night-shift driver Lee, who rents a 100-square-foot subdivided flat at HK$4,200 a month.

Lee, who has been waiting for a public flat for eight years, said: "I don't want to open the window because it faces the patio and the air is bad there. I'd rather go to the park for fresh air."

Lee relies on takeaways and instant noodles for lunch and dinner and he rarely consumes vegetables and fruits.

"My flat is too small and cooking fumes damage my health," Lee said. "I don't want to eat takeaways but I have no choice."

Peace Wong Wo-ping, the council's chief officer on policy and advocacy, said: "Subdivided flat tenants displayed poor health conditions but they could not build healthy living habits. This made them the main focus of primary medical services.

"The government released the Primary Health-Care Blueprint recently but promoting the service to grassroots families and expanding its coverage remains a concern. The government should enhance the capability of district health centers."

The council advised the government to increase the number of community pharmacies, build "community spaces" for primary health care and social work in densely populated areas such as Sham Shui Po and Yau Ma Tei, as well as set up a fund to support community organizations to provide disease prevention services.