Poor ventilation in new homes could lead to health problems for occupants, architecture experts have warned.
A lack of air vents or open windows leads to a build-up of pollutants and chemicals from furniture, flooring and plastics that is hard to detect, Glasgow School of Art's Mackintosh Environmental Architecture Research Unit (MEARU) said.
The unit claims most modern homes are being built to be airtight, which can cause problems for people with asthma and respiratory issues if they are not ventilated properly.
A public awareness film has been made by MEARU urging people to make sure they ventilate their homes.
Recommendations include keeping vents or windows open when cooking, showering and cleaning; drying laundry near an open window; and opening windows at night.
Professor Tim Sharpe, head of MEARU, said: "Poor indoor air quality, particularly in bedrooms, is hard for people to detect.
"There are clear links between poor ventilation and ill-health so people need to be aware of the build-up of CO2 and other pollutants in their homes and their potential impact on health.
"Modern homes are increasingly airtight and can also contain a great number of pollutants and chemicals, many of which can have serious health effects.
"It is clear from this research that buildings are simply not well ventilated and this could seriously impact on occupants' health, especially vulnerable people such as those with chronic obstructive pulmonary disease and asthma."
MEARU - which works between architectural design and scientific research - carried out a study of 200 modern homes and found "widespread evidence of poor ventilation, with bedrooms being a particular problem".
Prof Sharpe added: "In the past, some houses had plaques telling people to open their windows and public information films would offer similar advice.
"We hope that this film will help people to understand more about the need to ventilate and how best to ensure that they get the best possible indoor air quality so as to avoid problems of ill-health and the associated cost to our health system."
The Glasgow School of Art body worked with Hanover Housing Association during the study.
Development officer Kenneth Shepherd said: "It has been fascinating working with Professor Sharpe and the team at MEARU and receiving their conclusions has been very helpful.
"Going forward all our new residents will be provided with information on the best way of ensuring that they ventilate their homes properly."