Advances that boost energy efficiency in buildings, such as high-tech insulation, synthetic materials and mechanical air-conditioning, have made buildings more airtight – with potential health consequences for occupants.
A new white paper from Condair explores how facility managers can tackle infectious aerosols. ‘Making buildings healthier: protecting against the spread of infection’ first outlines the significant impacts indoor air quality can have on health and productivity, including its link to the spread of respiratory infection via contact, droplets and airborne aerosols.
Viral respiratory infections are almost exclusively transmitted from person to person indoors, it says. When people in the industrialised world interact, work, sleep and travel in enclosed spaces for the majority of their lives, transmission becomes increasingly likely.
Bringing fresh air into enclosed settings is an effective method for boosting indoor air quality and removing viral aerosol particles. Condair lists the following methods:
- ventilation from windows
- mechanical ventilation by air-conditioning, and
Addressing air humidity is also a factor. When indoor air is heated in cooler months, outdoor air or air brought in mechanically will begin to dry out. The colder the outside air, the lower its capacity to absorb water and the drier it becomes. The air will then try to restore its equilibrium by attempting to become saturated by drawing moisture from materials and bodies present. Viruses prefer dry conditions. Humidification systems are instrumental and temperatures should not be overheated – 20 to 22° celsius is ideal.
“A low level of humidity is one of the reasons for the seasonal occurrence of flu outbreaks,” says Yale professor of molecular, cell and developmental biology Akiko Iwasaki . “The world would be a healthier place if the humidity of the air in all of our public buildings were to be kept at around 40 to 60 percent relative humidity.”
Natural light, choosing the right materials and planning the right layout, fixtures and fittings are other considerations that, when properly put into action, can help with indoor air quality.
Daylight is known for its health benefits and can boost productivity.The lack of sunlight we experience as we spend large portions of our lives indoors contributes to the seasonal occurrence of respiratory infections in the cooler months.
Sunlight provides defence against viral infections as its UV components stimulate our immune systems and enhance the formation and mobility of the cells that tackle viruses. Sunlight also reduces the period during which many pathogenic microorganisms can remain viable. UV-C light can be applied as a defence against pathogens, but is harmful to the eyes and skin and must not be used in rooms where people are present. It can be applied to air in ventilation ducts after extraction.
While it’s of urgent importance during a global pandemic, keeping things germ free and ultra-hygienic is harmful to our immune systems in the long run. Condair’s paper says healthy buildings should enable interaction with the ‘good’ microbes present in our environment. Choosing the right materials can play an important part in encouraging the right atmosphere.
Manufactured materials like steel, glass and plastics, which help with energy efficiency, insulation and creating an airtight shell, also have an impact on moisture levels and are non-porous. Good microbes cannot survive in the dry, nutrient free environments these create and with no competitors for water and nutrients, pathogenic, multi-resistant microorganisms can propagate unopposed. Natural materials like tiles, plaster, clay and wood are preferred as they offer a better environment for diverse communities of microbes. Condair recommends installing porous-free, smooth, synthetic materials only in surfaces that are frequently touched and therefore must be routinely cleaned – like handrails, door handles and taps.
Coverings like rugs and carpets can reduce the levels of fine particulates within a room, trap dust particles and prevent resuspension into the air.
Factors that govern the flow and congregation of occupants – like the layout and number of interconnected rooms, doorways and hallways – can affect the risk of transmission. Popular layouts that emphasise openness, transparency and spaciousness can facilitate teamwork and interaction, but can also increase the risk. Pathogen spread may be better contained by reducing the number of high-occupancy rooms and ensuring a mix between open and closed spaces.