Children and adults around the world every year suffer from respiratory infections ranging from the commonplace cold all’influenza up to more serious illnesses. Little has been done to limit the impact of these diseases, consider something inevitable. But not so – write in Science 39 scientists from all over the world experts in the transmission of pathogens by aerosol – because new scientific knowledge, building engineering and adequate public health policies can allow us to control the air quality, just as we managed to control that ofwater and of foods to limit the transmission of diseases. We need to lay the foundations to ensure that the air in our buildings is clean, with significantly fewer pathogens, just like the water coming out of our taps adds. Cath Noakes, Professor of Environmental Engineering at the University of Leeds.
The clear message: this long-standing delay, also due to the (incorrect) denial of the role of aerosol in the transmission of respiratory diseases, we are paying dearly with the Covid-19 pandemic, but the time has come for a change paradigm, thanks to advances in scientific knowledge, because the tools to ensure the safety of closed environments are there, just use them. The teacher Lidia Moravian air quality expert at Queensland University of Technology (Australia), she is leading an international appeal, calling for universal recognition that infections can be prevented improving internal ventilation systemsjust as in the 1800s, cities began organizing clean water supplies and centralizing sewage systems.
Just in these days, with great delay, first the World Health Organization, then more markedly the American CDCs have updated the guidelines on how the coronavirus is transmitted, underlining the central role of aerosol, infectious respiratory particles that can float for a long time in the air and the dangers of closed, poorly ventilated and crowded environments.
Already in May 1945 Williams Wells, an American scientist who first understood that tuberculosis could be transmitted through respiratory droplets, complained about The Scientific Monthly (later absorbed by Science) that the delay in sanitary ventilation during a period of rapid development of water purification, milk pasteurization and food control is a public health paradox.
In fact, most developed countries would not tolerate a risk of infection of more than 1 in 10 thousand for drinking water or food. Yet in these same countries, children are affected several times by respiratory tract infections each year, including the flu that causes death among the elderly population. Governments around the world have rightfully invested money in ensuring adequate sanitation and clean water for the past 150 years. The respiratory infections instead they are considered as one an essential part of daily life. The huge iceberg under the surface of the water has not been seen, or the gigantic consequences brought about by diseases transmitted through the air.
The Covid-19 pandemic has put us in front of a reality that is now under everyone’s eyes with unparalleled human, social and economic costs. Over the years the role of the air circulating inside buildings in the spread of viruses has been neglected. Vaccines produced in record time are seen as the salvation, but in reality they are only one of the protective measures, he comments Giorgio Buonanno, professor of environmental technical physics at the University of Cassino, one of the authors of the document – it is now clear that vaccines, with the arrival of variants and the sometimes occurrence of infections despite immunization, alone will not be enough to overcome the pandemic. THE vaccines, we know, do not protect 100%. We must therefore also control the quality of the air, the means through which Sars-CoV-2 spreads with adequate ventilation of enclosed spaces. The mix of vaccines and ventilation can really make us return to pre-Covid life. And adequately ventilating buildings will also protect us from future pandemics.
There are for criticized which must be taken into account. it is much more difficult to catch airborne infections compared to those brought by contaminated water or food origin. The contamination of food or water almost always comes from an easily identifiable place such as a well, an aqueduct, a food and the consequences on health are practically immediate (generally gastrointestinal problems occur). There is no incubation period as long as for Covid-19. Furthermore, studies on air transmission are much more difficult because the air everywhere and the flows inside buildings are complex and there are no standardized measurement systems.
For decades, architects and engineers have been involved in the thermal comfort, odor control, energy consumption, completely omitting air quality control to prevent infections. To get there – add the scientists – you need a cchange in the paradigm in which we see the transmission of respiratory infections, assuming that the manageable risk, the treatable problem, just like the control of food and water to ensure public health. Just a little bit more difficult.
For pathogens such as Sars-Cov-2 it must be evaluated the risk of infection taking into account the type of emission (breathing, talking, singing), the size of the room, the number of people present, the time spent, how much the infectious agent can be transmitted. The urbanized society spends 90% of its time indoors. This does not mean that every environment must become a biosecurity facility, but that new buildings should be designed with consideration the activities that take place inside: a gym where athletes train by breathing intensely will have different ventilation standards than a cinema where the audience stopped, relaxed and in silence. It may sound complicated but there are already flexible models that can be applied.
Much can also be done for existing buildings with ad hoc interventions. The key measure to limit the airborne transmission of infectious diseases (not only Covid, but also flu, measles, colds) isventilation, supported by the filtration and from air disinfestation. Per ventilation means a quantity of outside air or appropriately filtered recirculation air. In buildings, according to WHO guidelines, an acceptable indoor air quality must be guaranteed, with adequate ventilation rates to limit odors and carbon dioxide. There are no indications to mitigate the spread of viruses and bacteria in the internal spaces coming from the respiratory activity nor precise limits on exposure to pollutants. Raising the frequency of air changes in existing systems could already be a starting point. And where this is not possible for structural (or economic) reasons, it is possible to intervene with portable purifiers.
Building ventilation standards must provide for a marked improvement in ventilation, filtration and disinfection of the air, monitors that allow the public to observe the quality of the air in real time indoors, thus making people more aware of requiring safe environments, and process designers add.
clear that more ventilation requires higher energy consumption, for this reason it must be adapted to the request of the moment. A serious problem that certain measures cannot be easily taken during a pandemic and most buildings were not designed to limit respiratory infections (except in modern hospitals).
The paradigm shift we need is much deeper than simply “rethinking” the way we manage buildings and transportation. It requires a change in the way humanity thinks about the transmission of respiratory infections, starting from the way hygiene is explained in school, or from how medical students or all subjects, from public health to health, are trained. engineering that have to do with these issues conclude the scientists. Ventilate environments to mitigate the spread of diseases transmitted by aerosols possible, just become aware of it, says Buonanno.
The utility is not only in safeguarding health, it is also (paradoxically) one matter of costs. The infection costs far outweigh the initial infrastructure costs to contain them. In the United States alone, the annual cost (direct and indirect) of the flu was calculated at 11.2 billion dollars in 2018; for respiratory infections other than influenza in 40 billion dollars (year 2003). When the final economic cost of the current pandemic becomes available it will become even clearer how much we are paying for the inertia of not investing in mechanical ventilation. The initial expenses for these investments would be borne by others than who pays the health care costs, so there may be resistance to investing. But in any complex system, costs and benefits are never homogeneously distributed: it is inevitable that the investment of one generates savings for others, for this reason, the scientists suggest, any incentives should be well distributed.
The advantages of investing in improved air quality will reduce not only the transmission of infectious diseases but also absenteeism in the workplace due to allergic reactions or due to sick building syndrome (clinical manifestations that occur in a large number of occupants who spend several hours in a building equipped with mechanical ventilation without the introduction of fresh air from the outside). Any expense for ventilation changes can be offset by a reduction in lost productivity. In short, everyone has to gain: employers and the health system.
May 14, 2021 (change May 14, 2021 | 12:42)
© REPRODUCTION RESERVED