**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 **isolation, quarantine and confinement** (**lockdown**) and, from the 19th century, the architectural and urban measures concerning air quality and sunlight.

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 [6], although "less uniform and prescriptive [7]".

Plagues were the deadliest pandemics. The 1346–1353 Black Death supposedly killed up to half of Europe's population [8]. 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 [11]. Tuberculosis deaths counts for 45% between 1790 and 1796 in Bristol, 33.2% of deaths between 1751 and 1778 in Marseille [12] and for 25% of death between 1810 and 1815 in New York City [13]. In 1900, it remained the third cause of mortality after cardiovascular diseases and influenza–pneumonia in the US [14].

In France, the backbone of the fight against tuberculosis was the **Hygiene movement** in which public health was supposed to scientifically guide political decisions, architecture and urbanism. The movement started in the 1820s, continued with the creation of the Hygiene Commissions (1848) and of the Commission for Unhealthy Housing (1950) [15] and reached its peak in the urban renewal during the Haussmann period as Seine (Paris) prefect (1853–1870). The French capital applied the hygiene reform at the largest scale ever seen: **sewage, wastewater treatment, waste removal, air circulation inside and between buildings, sunlight**.

**Hygiene movement derived principles definitively marked architecture and urbanism.** The sunlight that kills bacteria imposed the sanatoriums as general architectural models, with vast windows stretching from one side to the other of the room and terraces for sun baths. Sunlight and ventilation at the 45th parallel north are the reason for imposing distances in between buildings greater than the building height.

At the turn of the 20th century emerged the British **Garden City movement**, started with the Ebenezer Howard's 1898 book, republished in 1902 as *Garden Cities of To-morrow*. In Germany and Switzerland appeared the *Lebensreform* (Life Reform) movement.

The turn of the 20th century brought the first *International Congresses on Tuberculosis*: Berlin (1899), London (1901), Paris (1905). The *First International Congress for Sanitation and Housing Health Safety* was held in Paris (1904). The congress report correlates population density and health. The European research of the French dr. Samuel Bernheim concludes that "The tuberculosis mortality is proportional to the housing density; the danger of infection is all the greater when the residents are more cramped in their housings [15]".

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 [12].

The 19th century Hygiene movement marked the Interwar modernist architecture. Architect's **Le Corbusier** *Five Points of a New Architecture* are derived from Hygiene movement theories. The **house on** *pilotis*, reinforced concrete columns raising the house from the ground, allows aeration. The **roof garden** is inspired by the sanatorium sunbath terraces. The **free plan** allows the liberation from being the "slave of the load-bearing walls". The **horizontal window**, "essential goal of the house", which "runs from one end to the other of the façade" is directly taken from the 19th century recommendations. The **free façade** in front of the columns is a "lightweight membrane made of isolating walls or windows". Modernist urbanism is synthesized by the Le Corbusier architect book *Athens Charter* (1933) and the Josep Lluís Sert architect *Can our cities survive?* (1942). Hygiene movement principles were employed, emphasizing lighting and sunlight, light-oriented buildings and air circulation inside and between buildings.

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 [16].

The environmental counterreaction appeared in the late 1960s with the **green architecture**, as a reaction to the suburban sprawl and to the energy crisis. Different approaches are green city, sustainable city, eco city, zero & low carbon cities, zero energy city, livable city, compact city, smart city or resilient city. They concern pollution, carbon emission, energy, water, waste management and recycling, green-space ratios, forests and agricultural land loss.

The counterreaction to the social environment led in the US to the **New Urbanism** movement, in the 1980s. It emphasized mixed-use neighborhood and encouraged walking and bicycle transportation [17]. At the same time emerged in Europe the **Urban Village** movement that also promotes mixed use zoning aiming for partial self-containment by combining working, leisure and living, leads to medium-density housing, encourages walking and bicycling as well as public space encounters.
