Clean air as an experience good in urban China.

The surprise economic shutdown due to COVID-19 caused a sharp improvement in urban air quality in many previously heavily polluted Chinese cities. If clean air is a valued experience good, then this short-term reduction in pollution in spring 2020 could have persistent medium-term effects on reducing urban pollution levels as cities adopt new "blue sky" regulations to maintain recent pollution progress. We document that China's cross-city Environmental Kuznets Curve shifts as a function of a city's demand for clean air. We rank 144 cities in China based on their population's baseline sensitivity to air pollution and with respect to their recent air pollution gains due to the COVID shutdown. The largest experience good effect should take place for cities featuring a high pollution sensitive population and where air quality has sharply improved during the pandemic. The residents of these cities have increased their online discussions focused on environmental protection, and local officials are incorporating "green" industrial subsidies into post-COVID stimulus policies.

Air pollution lowers Chinese urbanites' expressed happiness on social media.

High levels of air pollution in China may contribute to the urban population's reported low level of happiness1-3. To test this claim, we have constructed a daily city-level expressed happiness metric based on the sentiment in the contents of 210 million geotagged tweets on the Chinese largest microblog platform Sina Weibo4-6, and studied its dynamics relative to daily local air quality index and PM2.5 concentrations (fine particulate matter with diameters equal or smaller than 2.5 µm, the most prominent air pollutant in Chinese cities). Using daily data for 144 Chinese cities in 2014, we document that, on average, a one standard deviation increase in the PM2.5 concentration (or Air Quality Index) is associated with a 0.043 (or 0.046) standard deviation decrease in the happiness index. People suffer more on weekends, holidays and days with extreme weather conditions. The expressed happiness of women and the residents of both the cleanest and dirtiest cities are more sensitive to air pollution. Social media data provides real-time feedback for China's government about rising quality of life concerns.

Data set from the Union Army samples to study locational choice and social networks.

We describe the publicly available data created by the NIA funded Early Indicators program project, often referred to as the Union Army data, and the subset of these data used in "Persistent Social Networks: Civil War Veterans Who Fought Together Co-Locate in Later Life" (Costa et al., Forthcoming) [1]. This data subset can be used for reproducibility and extensions and also illustrates how the original complex data derived from archival administrative records can be used.

Persistent Social Networks: Civil War Veterans Who Fought Together Co-Locate in Later Life.

We demonstrate the long reach of early social ties in the location decision of individuals and in their older age mortality risk using data on Union Army veterans of the US Civil War (1861-5). We estimate discrete choice migration models to quantify the trade-offs across locations faced by veterans. Veterans were more likely to move to a neighborhood or county where men from their same war company lived and were more likely to move to such areas than to areas where other veterans were located. Veterans also were less likely to move far from their origin and avoided urban immigrant areas and high mortality risk areas. They also avoided areas that opposed the Civil War. This co-location evidence highlights the existence of persistent social networks. Such social networks had long-term consequences: veterans living close to war-time comrades had a 6% lower probability of dying.

DEATH AND THE MEDIA: INFECTIOUS DISEASE REPORTING DURING THE HEALTH TRANSITION.

In the late 19th Century, cities in Western Europe and the United States suffered from high levels of infectious disease. Over a 40 year period, there was a dramatic decline in infectious disease deaths in cities. As such objective progress in urban quality of life took place, how did the media report this trend? At that time newspapers were the major source of information educating urban households about the risks they faced. By constructing a unique panel data base, we find that news reports were positively associated with government announced typhoid mortality counts and the size of this effect actually grew after the local governments made large investments in public water works to reduce typhoid rates. News coverage was more responsive to unexpected increases in death rates than to unexpected decreases in death rates.

Optimal real estate capital durability and localized climate change disaster risk.

The durability of the real estate capital stock could hinder climate change adaptation because past construction anchors the population in beautiful and productive but increasingly-risky coastal areas. However, coastal developers anticipate that their assets face increasing risk and this creates an incentive to seek adaptation strategies. This paper models climate change as a joint process of (1) increasingly destructive storms and (2) a risk of sea-level rise that submerges coastal property. We study how forward-looking developers and real estate investors respond to the new risks along a number of dimensions including their choices of location, capital durability, capital mobility (modular real estate), and maintenance of existing properties. The net effect of such investments is a more resilient urban population.

Declining Mortality Inequality within Cities during the Health Transition.

In the United States in the late 19th and early 20th century, large cities had extremely high death rates from infectious disease. Within major cities such as New York City and Philadelphia, there was significant variation at any point in time in the mortality rate across neighborhoods. Between 1900 and 1930 neighborhood mortality convergence took place in New York City and Philadelphia. We document these trends and discuss their consequences for neighborhood quality of life dynamics and the economic incidence of who gains from effective public health interventions.

China's bullet trains facilitate market integration and mitigate the cost of megacity growth.

Megacity growth in the developing world is fueled by a desire to access their large local labor markets. Growing megacities suffer from high levels of traffic congestion and pollution, which degrade local quality of life. Transportation technology that allows individuals to access the megacity without living within its boundaries offers potentially large social benefits, because individuals can enjoy the benefits of urban agglomeration while not paying megacity real estate rents and suffering from the city's social costs. This paper presents evidence supporting the claim that China's bullet trains are playing this role. The bullet train is regarded as one of the most significant technological breakthroughs in passenger transportation developed in the second half of the 20th century. Starting in 2007, China has introduced several new bullet trains that connect megacities such as Beijing, Shanghai, and Guangzhou with nearby cities. Through facilitating market integration, bullet trains will stimulate the development of second- and third-tier cities. By offering households and firms a larger menu of location alternatives, bullet trains help to protect the quality of life of the growing urban population. We document that this transport innovation is associated with rising real estate prices in the nearby secondary cities.

Economic conditions predict prevalence of West Nile virus.

Understanding the conditions underlying the proliferation of infectious diseases is crucial for mitigating future outbreaks. Since its arrival in North America in 1999, West Nile virus (WNV) has led to population-wide declines of bird species, morbidity and mortality of humans, and expenditures of millions of dollars on treatment and control. To understand the environmental conditions that best explain and predict WNV prevalence, we employed recently developed spatial modeling techniques in a recognized WNV hotspot, Orange County, California. Our models explained 85-95% of the variation of WNV prevalence in mosquito vectors, and WNV presence in secondary human hosts. Prevalence in both vectors and humans was best explained by economic variables, specifically per capita income, and by anthropogenic characteristics of the environment, particularly human population and neglected swimming pool density. While previous studies have shown associations between anthropogenic change and pathogen presence, results show that poorer economic conditions may act as a direct surrogate for environmental characteristics related to WNV prevalence. Low-income areas may be associated with higher prevalence for a number of reasons, including variations in property upkeep, microhabitat conditions conducive to viral amplification in both vectors and hosts, host community composition, and human behavioral responses related to differences in education or political participation. Results emphasize the importance and utility of including economic variables in mapping spatial risk assessments of disease.

Health, wartime stress, and unit cohesion: evidence from Union Army veterans.

We find that Union Army veterans of the American Civil War who faced greater wartime stress (as measured by higher battlefield mortality rates) experienced higher mortality rates at older ages, but that men who were from more cohesive companies were statistically significantly less likely to be affected by wartime stress. Our results hold for overall mortality, mortality from ischemic heart disease and stroke, and new diagnoses of arteriosclerosis. Our findings represent one of the first long-run health follow-ups of the interaction between stress and social networks in a human population in which both stress and social networks are arguably exogenous.