THE COVID-19 pandemic has highlighted the importance of providing adequate ventilation for indoor spaces.

Indoor ventilation relates to the movement and distribution of air into and throughout a building. As more buildings are designed to increase energy efficiency, inadequate ventilation is increasingly becoming an important public health concern due to its correlation with the incidence of upper and lower respiratory tract infections, especially in vulnerable populations such as children and the elderly. When an individual sneezes, the plume can travel as far as eight metres, at 35 metres per second. This therefore means that when someone with a respiratory infection such as the seasonal flu sneezes, small particles containing viruses and bacteria are released. Aided by poor ventilation in a building, the concentration of contaminants in the air increases the risk for transmission of a respiratory illness to individuals occupying the said space.

Economic and social effects associated with poor ventilation in buildings

Adequate ventilation is determined based on the size and occupancy of a space. Where inadequate ventilation exists in buildings it has a direct impact on human capital and results in productivity loss, increased absenteeism, and creates a burden on the health-care system. Annually, in some countries approximately $2.9 billion is spent on over-the-counter drugs and another $400 million on prescription medicines for the relief of symptoms related to illnesses such as the common cold. Seventy-five per cent of those who get a respiratory illness also take a minimum of two to three days off to recuperate.

Signs of poor ventilation in a building

• Sick Building Syndrome in which symptoms of illnesses such as nausea, fatigue, shortness of breath, runny nose and itchy skin are triggered due to spending time in a particular building

• Windows and glass in a building appear frosted due to condensation

• Signs of mould growth can be seen on structural surfaces like walls and ceilings

• Strong odours in a building that do not dispel

• Heat build-up and high humidity in a space for prolonged periods that do not dissipate.

Ways to improve ventilation in buildings, hence minimising the spread and impact of infectious respiratory illnesses

Increase the introduction of outdoor air by:

• Opening windows and doors when weather and other conditions permit

• Using fans to increase the effectiveness of open windows

• Installing fans in a manner so that they do not blow air from one person to another.

When designing buildings, ensure that windows and doors are positioned correctly and are sized to equal a minimum of ten per cent of the floor area of a given space.

Avoid placing fans or designing air conditioning systems in a way that could potentially cause air to flow directly from a contaminated area to a clean area.

Ensure that ventilation systems such as hoods and other units work efficiently by providing and maintaining indoor air quality based on the occupancy level and the nature of the activity done within the space.

Develop and maintain preventive maintenance schedules for ventilation systems to ensure that units are cleaned, and that air filters and other parts are within their recommended service life.

Ensure that restrooms are vented in such a manner that exhaust fans and windows located within the space pull contaminated air outside of the building.

Reduce overcrowding in buildings such as classrooms so that air change per hour (ACH) is maintained at a minimum level of 4 ACH. Note that the more persons in a space, the more rapid the air exchange required.

Consider removing particles from the air through the installation of air purifying machines.

In non-residential settings, run ventilation and air conditioning systems at maximum outside airflow for two hours before and after the building is occupied. This allows for the air in the space to be refreshed before arrival of the occupants, and ensures as well the removal of contaminants from the air that might still remain after the use of the space.

Benefits of having adequate ventilation in buildings

During the months of October to March respiratory illnesses such as the common cold and influenza continue to have a tremendous negative impact on the populace of many countries. In 2019 published data associated with the incidence of respiratory illnesses in Jamaica demonstrated that six deaths were attributable to influenza; and while not categorically stating there was a direct link between indoor ventilation and the occurrence of these deaths, it is a known fact that where poor ventilation exist in indoor spaces, illnesses such as influenza and others of similar nature spread easily.

The flu virus, in particular, is considered to be highly contagious and survives for up to 24 hours in some environments. Rhinoviruses such as those which cause the common cold behave in a similar manner, lasting up to nine hours in the air after been released — especially in improperly ventilated spaces. Allergic asthma and other sick building illnesses are of no less importance in relation to the need for proper ventilation in buildings. Improving ventilation in buildings will therefore result in a decrease in the associated mortality and morbidity rates, decreased absenteeism due to sick days, decreased health-care costs, and increased human productivity..

Karlene Atkinson is a public health specialist and lecturer at the School of Public Health, University of Technology, Jamaica.