This chapter aims to assess the historical role of architecture and urbanism in the prevention and mitigation of pandemics and the place it may occupy in future international strategies. During COVID-19, the contemporary healthcare system response to pandemics showed its limits. There must be investigated a more interdisciplinary answer in which the role of the built environment in the One Health should be clarified. Since the 19th century, the built environment traditionally occupied a decisive role in mitigating pandemics. The war against tuberculosis led to the Hygiene movement which set the principles of the Modernist architectural and urban movement. With the discovery of antibiotics, the medicine emancipated from architecture. In the absence of health implications, the social and environmental counterreactions to the Modernist movement led to the Green Architecture, New Urbanism or Urban Village movements. After the last decades warnings about future pandemics, some of the present COVID-19 scientific findings have notable impact on the built environment design: pollution, green areas, urban population density or air quality control. Finally, the chapter analyses architectural and urban measures for preventing and mitigating future pandemics: air control, residential approaches, public spaces, green areas design, working, transportation and mixed neighborhoods.
- green buildings
- built environment
This chapter aims to reveal the role of architecture and urbanism in the prevention and mitigation of pandemics. Although since the 19th century the built environment traditionally had a decisive role in mitigating pandemics, such as tuberculosis, the emancipation of medicine, after the discovery of antibiotics, gradually excluded architecture and urbanism from the strategies against pandemics. In the context of COVID-19, there are relevant reasons for an interdisciplinary scientific approach of pandemics including the built environment and for a reevaluation of the future international strategies.
2. The limits of the contemporary healthcare system response to pandemics
In the second half of the 20th century, a complex set of measures was set in place that successfully fought against pandemics. Pharmaceutical interventions brought substances such as antibiotic drugs against tuberculosis or such as vaccine products against influenzas. In 1997, International Coordination Group (ICG) was established by the World Health Organization (WHO) “to manage and coordinate the provision of emergency vaccine supplies and antibiotics to countries ”. Unfortunately, although existing influenza vaccines are among the most effective protections and strategic stockpiles for several influenza types are gathered, they are ineffective against new strains. Developing and distributing a new vaccine takes several months, delaying the pharmaceutical response. As for antibiotics, WHO started, since the 1990s, to strengthen the surveillance of the drug resistance for the tuberculosis.
Lack of pharmaceutical means, non-pharmaceutical interventions “should be put in place, at the early stage of a pandemic ”. The foreseen interventions included hygiene, social distancing, using facemasks and schools’ closures. The non-pharmaceutical interventions were established as part of the international response interventions: anticipation, early detection, containment, control and mitigation as well as elimination or eradication. These measures were regulated, since 1969, by the International Health Regulations that aimed to “prevent, protect against, control and respond to the international spread of disease”. Events that might have international consequences were supposed to be promptly reported by the states to WHO for assessment.
The COVID-19 pandemic showed the limits of the existing healthcare system strategies. By the end of 2020, lack of adequate response, the pandemic led to a dramatic health impact, with more than 1.5 million deaths by December 2020 , to a huge social disruption and an economic result that brought to the biggest global recession since the 1930s Great Depression.
The COVID-19 pandemic brought into attention other
3. The One Health system response to pandemics and the role of the built environment
In the 1980s, after increased outbreaks of zoonoses, human healthcare system became aware of the benefits in approaching human and animal diseases together with the unifying concept of One Medicine . In the 1990s, due to the alteration of the ecosystems which led to new ways of diseases spread, the role of the environment in human health became relevant . During the decade of the 2000s, the unification was extended to the humans, animals and environment resulting the One Health system in the 2000’s [4, 5]. A broader spectrum of professions was brought together, gathering
The 2010 decade brought an increased awareness of the urbanization risks for pandemics. The approaches were quantitative and focused on the
Despite these advances in understanding the role of the built environment in human health, by the end of 2020 the was still not international strategy that included buildings and the built environment in the fighting against pandemics.
4. The historical role of the built environment in pandemics before the advent of antibiotics
Until the arrival of antibiotics in the middle of the 20th century, the main historical methods against bacterial pandemics were limiting the contacts between individuals through
In the case of leprosy, containment led to the appearance of the first dedicated architectural program, the leprosarium. The measure was common in Medieval Europe , although “less uniform and prescriptive ”.
Plagues were the deadliest pandemics. The 1346–1353 Black Death supposedly killed up to half of Europe’s population . They pushed to a diversification of measures aiming the limitation of contacts between individuals, such as isolation, quarantine, confinement, the use of plague mask and the introduction of the medical passport. They also led to dedicated constructions, such as the 27 km long, six feet tall, Plague Wall in the French Vaucluse mountains traced in 1721 [9, 10]. Since the 19th century, plagues impact diminished.
The tuberculosis, “the white plague”, took the relay, with a peak mortality rate in Western Europe in 1800 . Tuberculosis deaths counts for 45% between 1790 and 1796 in Bristol, 33.2% of deaths between 1751 and 1778 in Marseille  and for 25% of death between 1810 and 1815 in New York City . In 1900, it remained the third cause of mortality after cardiovascular diseases and influenza–pneumonia in the US .
In France, the backbone of the fight against tuberculosis was the
At the turn of the 20th century emerged the British
The turn of the 20th century brought the first
The hygiene measures led to a decline of tuberculosis and, at the turn of the 20th century, mortality was reduced at half in Paris between 1872–1900 and 1901–1925 periods .
The 19th century Hygiene movement marked the Interwar modernist architecture. Architect’s
One year later, in 1943, the discovery of the streptomycin antibiotic brought the first effective treatment for tuberculosis. The health strategies against bacterial pandemics no longer needed the support of architecture and urbanism.
5. Architecture and urbanism after the emancipation of medicine
As human health ceased to be an architectural and urban issue, Modernist movement, that promoted air, sun and light, was judged by social and environmental concerns determined by the functional segregation and the automobile-based traffic. In 1972 was symbolically declared the death of the modernist movement with the demolishment of a 1955 modernist US housing planned according to the principles of Le Corbusier .
The environmental counterreaction appeared in the late 1960s with the
The counterreaction to the social environment led in the US to the
6. Health engaged architecture and urbanism certifications
At the end of the 20th century were introduced building certification systems. At the architectural level, green building certifications of the 1990s concerned health issues, such as the 1990 Building Research Establishment’s Environmental Assessment Method (BREEAM) and the 1993 Leadership in Energy and Environmental Design (LEED). They relate to
More health-oriented certifications started in the 2010s with the 2012 Fitwel, a joint initiative led by the US Centers for Disease Control and Prevention (CDC) and General Services Administration (GSA), or WELL Building Standard from the International WELL Building Institute, launched in 2014.
At the urban scale, healthy cities topics are only generally addressed by initiatives such as the WHO European Healthy Cities Network or the Urban Low Emissions Development Strategy (Urban LEDS). As for the LEED for Neighborhood Development, it repeatedly addressed health as a main issue: preferred location within existing cities to
7. The last decades warnings about future pandemics
According to a 2008
During the last decades, there was such concern about the zoonotic diseases impact that the COVID-19 pandemic seems the precise illustration: “
8. COVID-19 scientific findings with impact on the built environment design
The inevitable came with the COVID-19 pandemic. It led to an important allocation of resources in scientifically addressing the pandemic. Although the most notorious studies concern vaccines and antivirals, other research directions regard non-pharmaceutical measures aimed to prevent or mitigate pandemics. As in the 19th century, the implementation of some of these findings needs a
Air pollution was already subject to studies that proved the effects on human health, such as respiratory diseases or lung cancer . The correlation between road traffic, pollution and health has been associated with heart disease mortality .
8.2 Green areas
Pre-pandemic studies already concluded not only that “the percentage of green space in people’s living environment has a positive association with the perceived general health ” but also “consistent negative association between urban green space exposure and mortality, heart rate, and violence, and positive association with attention, mood, and physical activity ”.
8.3 Urban population density
Studies carried over time aimed to determine the correlation between population density and pandemics. For the 1918 Spanish flu, in England and Wales, research found “30–40% higher rates in cities and towns compared with rural areas” but “no association between transmissibility, death rates and indicators of population density and residential crowding ”. A research on India stretches that districts with a lower density experienced lower rates of population loss . A US research revealed “the positive correlation between population density and influenza mortalities ” although another paper finds no significant correlation between population density and transmissibility measured by the reproductive number (R) . As for Japan, a paper concluded that “lower morbidity in the towns and cities is likely explained by effective preventive measures in urban areas .”
Other researchers investigated the correlation between population density and epidemics of tuberculosis or avian flu [46, 47, 48, 49]. Paper also discussed on the impact of urban form and land use on the transmission of vector-borne viruses .
Those conclusions must be correlated with studies that include income, education or health care systems [36, 59]. A study involving more variables was realized in Italy, showing that population density was not statistically significant but, instead, car and firm density were positively associated with higher fatality rates .
These researches are limited though by the ability of collecting geolocation data. In the US and in the EU, gathering spatial data about people movements was neither intended by the governments nor embraced by citizens’ free participation .
8.4 Air control
Respiratory route transmitted diseases can spread either by droplets or by aerosols (suspensions in air of finer particles). By 2020, “virtually all infectious disease dynamics models on influenza have thus far ignored aerosol-transmission ”.
Research conducted during the COVID-19 pandemic showed that aerosols could be one of the most dangerous way of transmission in the interior spaces. A paper concluded that “virus could be detected in aerosols up to 3 hours post aerosolization ”. The badly ventilated rooms present the highest risk as an article on a Wuhan Hospital shows that the highest virus concentration was found in the toilets .
A 2020 research shows that
Studies show also that recirculating the air without proper filtration presents a potential risk. According to the study of a closed restaurant in Guangzhou, published on 2 April 2020, “droplet transmission was prompted by air-conditioned ventilation” and therefore the virus might have traveled through the central HVAC system . The finding was confirmed by the April 2020 statement of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHARE) that “infectious aerosols can be disseminated through buildings by pathways that include air distribution systems and interzone airflows ”.
9. Architectural and urban measures in mitigating pandemics
During the COVID-19 pandemic, the established principles were opposed to contrary solutions:
the need for creating public spaces for encounters was replaced by social distancing
the dense city paradigm, as opposed to the urban sprawl, posed virus transmission problems
encouraging public transport was replaced by the individual transportation.
Based on the scientific findings during the COVID-19 pandemic and based on previous experiences, architecture and urbanism can provide solution with the design of the buildings and of the built environment:
interior spaces: air quality
residential: middle density and the intermediate housing
public spaces: the key for the social interaction
green areas: a perennial goal
working: downsizing and dispersion
shopping: proximity and downscaling
transportation: walking, bicycling, shared mobility and robo-taxies
city scale: mixed use neighborhoods
9.1 Interior spaces: air quality
In the interior spaces, the virus transmission can be reduced by air control through ventilation, humidifying and filtering.
A 2020 research shows that 3 air changes per hour, which is common in most countries legislation, “generated reductions in expected outbreak sizes that would normally only be possible with a substantial vaccination coverage of 50–60%, which is within the range of observed vaccination rates in school settings ”.
As for filtering, pre-pandemic experiments have been conducted since 1968 on the efficiency of HEPA filters that “showed an average reduction of 99.996% ” or in which “aerosol transmission of PRRSV occurred in 0 of the 10 HEPA-filtration replicates ”. During COVID-19 pandemic, HEPA filters were recommended in hospitals for air filtering in operating rooms or in the breathing circuit [68, 69]. Some papers recommend HEPA for filtering the recirculating air in closed rooms or vehicles [70, 71], although certain studies are reserved concerning the HEPA filters capacity of filtering submicron size particles .
Humidifying could play an important role as long as a 2013 research concluded that “maintaining indoor relative humidity >40% will significantly reduce the infectivity of aerosolized virus ”.
As in the 19th century, air control becomes a key measure in mitigating pandemics in 2020.
9.2 Residential: middle density and the intermediate housing
There seems to be a conflict between epidemiologic studies that suggest a lower people density and the environmental approach that recommends the increasing of the built density. The urban sprawl is considered to increase pollution, to cause the loss of a sense of community , global warming , higher transportation costs and create health effects due to the dependence on automobiles . It is addressed by professional organizations such as Architects’ Council of Europe, the American Institute of Architects and the American Planning Association, by agencies such as European Environment Agency or by national legislation, such as the French law for Solidarity and Urban Renewal.
On the other hand, lowering the people density is not only implied by studies carried over time that correlate population density and pandemics but also the public preference. Pre-pandemic surveys showed that 76% of French  and 80% of US Americans  would choose to live in single-family houses. The COVID-19 pandemic increased this desire. Teleworking and the reduced access to shops, “led to a reduced demand for housing in neighborhoods with high population density”, trend which strengthen after the market recovery in June 2020 .
A more detailed approach should also be based on studies carried over the virus transmission in the interior spaces. Small, confined and poorly ventilated spaces, such as stairs or elevators, must be carefully planned as they are the most susceptible for aerosol contamination .
Medium density environments are the mostly supposed to reach this goal. Both New Urbanism and Urban village movements promote medium density housing. There are urban and architectural approaches that stay in between the single family detached house and the block paradigm. The French Intermediate Housing concept addresses buildings with more than one superposed apartments and with private access to each apartments. The definition appears in a French 1973 decree: the social intermediate housing (
9.3 Public spaces: the key for the social interaction
One of the problems the COVID-19 pandemic created was the social disruption. The public space was put under scrutiny . In this matter, exterior public spaces could play a key role. The COVID-19 droplets transmission occurs up to 6 feet (2 meters). According to Edward T. Hall’s proxemics theories, the social distance far phase is in between 7 and 12 ft. (2.1–3.7 m) and the public distance is in between 12 and 25 ft. (3.7–7.6 m) for the close phase and more than 25 ft. (7.6 m) for the far phase. Therefore, far social and public contacts could be achieved in exterior spaces without transmission risks.
According to Jan Gehl’s theories, social contacts in public spaces are among the most important. They have the characteristic of being spontaneous because people interact as a result of necessary or optional activities. The space in between the buildings is ideal for conversation, greetings, children playing: “life between buildings as dimension of architecture, urban design and city planning to be carefully treated ”.
9.4 Green areas: a perennial goal
As recent scientific studies show, green areas can improve the response to pandemics. They were already present in the 1900s urban theories and they maintain their permanent importance.
9.5 Working: downsizing and dispersion
Architectural measures can be taken in the case of office buildings. Some approaches concern general building measures, such as air control by ventilation filtration and humidification. Other methods should lean on morphologic changes that consider access separation and office space distribution.
There is also question of the offices size and their urban distribution. During the COVID-19 pandemic, an Italian multicriterial research concluded that firm density, based on an over 250 employees firm index for each region, was positively associated with higher fatality rates .
The COVID-19 pandemic also accelerated the use of telecommuting (teleworking or working from home). In 2019, 5.5% of workers in the US already worked from home  and, in April 2020, already 20% of Americans were able to work from home and doing so . Estimations from 2020 are that “37 percent of U.S. jobs that can plausibly be performed at home account for 46 percent of all wages ”. Telecommuting has an indirect environment impact by reducing the greenhouse emissions, fuel and energy usage and network congestion [86, 87].
9.6 Shopping: proximity and downscaling
Apart air quality methods, different measures can be taken for shops. Reducing the size cold lead to a better ventilation and less potential contacts. Proximity shopping is also an environmental desideratum as it allows for less automobile transportation, lead to pedestrian cities, reduced pollution, less energy consumption and less environmental impacts. Recent study shows that “to achieve a balance between energy consumption, GHG [Greenhouse Gas] emissions and energy generation potential, a neighborhood should contain an optimal ratio of commercial to residential buildings of about 0.25 .”
The proximity and downscaling decision have long term social and environment motivations more than short term economic reasons. An example are hypermarkets, huge stores combing supermarkets to department stores. It is symptomatic how France, the country that first implemented hypermarkets with Carrefour, in 1963, prevented their implantation in cities ten years later, by the Royer law which regulated the creation of shops over 1500 m2 inside towns.
9.7 Transportation: walking, bicycling, shared mobility and robo-taxis
Before the pandemic there was already very strong evidence of aerosol transmission over long distances . Studies during 2020 showed substantial transmission in closed vehicles and suggest “future efforts at prevention and control must consider the potential for airborne spread of SARS-CoV-2, which is a highly transmissible pathogen in closed environments with air recirculation ”. At the beginning of 2020, studies drew a warning about public transportation showing that, for New York City, the subway system was the major disseminator of COVID-19 .
To keep the present transportation system there could be applied methods that reduce the viral transmission. Airborne virus spread in public transport can be reduced by installing HEPA filters and surface disinfection can be done by UV disinfection.
There is also question of changing the current transportation paradigm. Changes that may reduce the virus transmission in the transportation system already begun before the COVID-19 pandemic. Cities designed at the scale of walking or bicycle distances were proposed by the 1900s Garden City movement, the 1970s Intermediate Housing or 1980s New Urbanism and Urban Village movements.
Mobility sharing with bicycles can increase the efficiency of an urban public transport network  and has health benefits . Starting with the white bicycle and white path proposed by the Provo movement in Amsterdam, in 1965, the Vélib’ in Paris, launched in 2007 and reached the Chinese bike sharing system where the two largest operators, Ofo, launched in 2014, and Mobilke 2015, totalize over 50 million orders per day . Electric car sharing, on which UV disinfection could be applied, could be a pandemic and environmental solution too. It has a positive environmental approach by “reducing 29% of CO2 emissions and increasing 36% electric vehicle adoption, when compared to the business-as-usual scenario ”. Along with UV disinfection, robo-taxis (robo-cabs, self-driving taxis or driverless taxis) could be used. Experiment in Beijing with electric robo-taxis showed a good impact in lower energy consumption, zero tailpipe emissions, traffic decongestion and reduced health risks  while simulation in Milan “propose that introducing a robo-taxi fleet of 9500 vehicles, centered around mid-size 6 seaters, can solve traffic congestion and emission problems in Milan ”.
From the larger urban point of view, transportation is influenced not only by the means of transport but also by the overall cities’ organization.
9.8 City scale: mixed use neighborhoods
Reducing transportation while maintaining social contacts and the access to urban facilities is a key aspect in preventing and mitigating pandemics. Research done during the 2020 pandemic suggest that “connectivity matters more than density in the spread of the COVID-19 pandemic ”. The risks are represented by commuting, tourists and businesspeople. Studies emerged during pandemic concern health inequities derived from the urban development .
This desideratum can be reached by designing mixed use neighborhoods that could concentrate transportation on walking and bicycling. These neighborhoods are likely to lead to a medium density environments . They should combine living with working, leisure, education and public space encounters.
The concept is not new, as it is already present in Ebenezer Howard’s Garden City with self-contained mixed-use new towns and socially mixed population. It is also relevant for the US 1980s New Urbanism or for the European Urban Village.
There is a consistent scientific literature about the opportunities highlighted by COVID-19 pandemic in different domains. There is also an expressed confidence that “architecture and urbanism after the COVID-19 epidemic will never be the same ”. Some built environment related trends may be accelerated by the pandemic:
the recognition of the role of environmental impacts on zoonosis, such as deforestation and destroying natural habitats
an increased awareness of the public space importance
the architectural research on new medium density typologies
the acceleration of promoting mixed-use neighborhood and encouraging walking and bicycle transportation
accelerate advancements in transportation such as shared mobility and robo-taxis.
Healthcare shape our cities and vice versa.
Although fighting against pandemics was traditionally associated with the built environment, the 20th century pharmaceutical progress allowed medicine to emancipate from architecture and urbanism. As WHO stated in 2018, “Will history repeat itself? The answer must be: Yes, it will .” Last decades evolutions which culminated with the COVID-19 pandemic stretched the role of a new interdisciplinary strategy in both combating and mitigating future outbursts.
There is an important COVID-19 scientific literature concerning pollution, green areas role, urban population density or air control that can be addressed mainly through built environment measures. These measures include air control, residential measures, public spaces, green areas design, working, transportation and mixed neighborhoods.
The COVID-19 pandemic dramatic implications can be also perceived as an opportunity for setting up a more stable health and built environment systems. Scientific evidence is not enough and it should be doubled by public awareness and by political implication. Otherwise, it may end like