Indoor heat levels in Hong Kong’s subdivided flats and rooftop huts felt like a blistering 52.21 degrees Celsius (126 Fahrenheit) this summer, with 80 per cent of homemakers living in those homes reporting dizziness and headaches, according to a survey released on Sunday.

The study, conducted by CarbonCare InnoLab and the Concerning Subdivided Units Alliance, surveyed 86 households across nine districts from June 22 to July 12, with 78 living in subdivided flats or rooftop huts, among other inadequate housing units.

It measured “apparent temperatures” – referring to how hot people actually feel, taking humidity into account – which averaged 35.58 degrees during daytime, with the highest of 52.21 degrees recorded in a subdivided flat, the survey showed.

Average temperatures reached 29.93 degrees during the day and 29.42 degrees at night, both exceeding the Hong Kong Observatory’s threshold of 28 degrees for a “hot night”.

Homemakers, who made up 48 per cent of the households surveyed, were the most affected group, with about 83 per cent saying they often or always felt fatigued.

About 80 per cent of them reported at least one heat-related physical symptom including feeling very thirsty, dizzy and having a headache, while 69 per cent said the heat in their homes affected their mood, according to the study.

Across all respondents, 70 per cent said that their sleep quality had been affected, and 74 per cent reported heat-related discomfort.