How much room you have in your house. The length of your commute. Your job and race.

These are some of the environmental and social factors that affect susceptibility to the novel coronavirus, and they’re working in concert to put Black residents in the nation’s capital at disproportionate risk of sickness and death, according to a new study by University of Maryland researchers.

Published last week in the journal Sustainable Cities and Society, the research paper by Ming Hu, assistant professor of architecture; Jennifer Roberts, assistant professor of kinesiology; Gesine Pryor M.Arch. ’21 and David Milner ’20 investigates links between the “built environment” of Washington, D.C., and social determinants of disease like health care access, poverty and racism. The study also uses statistical modeling to project where disease hotspots are likely to emerge in Washington, providing insight into potential protective responses.

“This pandemic has been exacerbated by so many aspects of how we live,” said Hu, the study’s first author. “You can’t just narrow it to an outbreak of infectious disease, and not consider the many things that influence who gets this disease and who dies when they get it.”

Across the city, the three wards with majority African American populations—5, 7 and 8—also lead in COVID-19 death counts, according to the city’s data. Black people account for about three-fourths of all D.C. fatalities from the disease, though they comprise only 44% of the city’s population; their median household income is around one-third of white residents’ income.

“When you have a group of people living with all these adverse social determinants of health and who are relatively impoverished, there are not many resources for them to deal with this new disease running rampant,” co-author Roberts said.

Based on an analysis of disease and housing data, the study found the No. 1 influencer on COVID-19 death rates was crowding in residences, which facilitates virus transmission. Although many of the neighborhoods inhabited by Black Washingtonians are classified as “mid- to low-density” areas by urban planning standards, Hu said, the modest single-family houses common in wards 7 and 8—with populations more than 90% African American—are often packed. The opposite condition prevails in many wealthier, whiter neighborhoods that have higher urban density but much less crowding, along with far-lower death counts.

Commute duration is another indicator for disease uncovered in the study. Residents of wards 7 and 8 endure the longest commutes in D.C., in part because nearly half of families don’t have cars, the study reported. Riding public transit in already poorly served “transit deserts” like wards 7 and 8—especially now that some lines have been suspended during the pandemic—can result in overcrowding. That puts residents in closer contact with more people who may have the disease, said Roberts, whose research focuses on the roles of public transit within built environments and its impact on health.

Another top risk factor was being a frontline worker: Wards 7 and 8 have above-average proportions of essential workers, with ZIP code 20020, which straddles the wards, having an approximately 50% higher rate of health care workers and double the rate of transportation, warehouse and utility workers compared to entire city.

Jobs and housing conditions work together to intensify risk.

“We saw such a large portion of frontline workers who are at risk each day, and it’s not like you come home to an empty house, or just your spouse,” Roberts said. “These may be multi-family or multi-generational households, and now you’re combining multiple pathways to exposure.”

Based on such variables, the study that was written before the current nationwide surge of COVID-19 cases predicted ZIP code 20020 in particular could turn into a potential hotspot for COVID-19 cases—a trend that is now playing out as the area’s Naylor-Hillcrest neighborhood has become one of the biggest centers of new infections in Washington.

“20020 is one of the hottest spots right now, and the trend line is going up,” Hu said.

The researchers say little can be done in the short term to reverse decades of segregation and underinvestment that help to elevate COVID-19’s death toll among Black people in the capital. However, emergency measures like temporary housing for essential workers or more frequent buses coming from certain neighborhoods could save vulnerable lives this winter, they said.

“We can’t predict when surges might happen, but we can say where they might happen, so officials can have resources and plans ready to help if these COVID-19 cases do spike up,” Roberts said.