Research Hub

Objective: To evaluate the short term associations between nitrogen dioxide (NO2) and total, cardiovascular, and respiratory mortality across multiple countries/regions worldwide, using a uniform analytical protocol.

Design: Two stage, time series approach, with overdispersed generalised linear models and multilevel meta-analysis.

Setting: 398 cities in 22 low to high income countries/regions.

Main outcome measures: Daily deaths from total (62.8 million), cardiovascular (19.7 million), and respiratory (5.5 million) causes between 1973 and 2018.

Results On average, a 10 μg/m3 increase in NO2 concentration on lag 1 day (previous day) was associated with 0.46% (95% confidence interval 0.36% to 0.57%), 0.37% (0.22% to 0.51%), and 0.47% (0.21% to 0.72%) increases in total, cardiovascular, and respiratory mortality, respectively. These associations remained robust after adjusting for co-pollutants (particulate matter with aerodynamic diameter ≤10 μm or ≤2.5 μm (PM10 and PM2.5, respectively), ozone, sulfur dioxide, and carbon monoxide). The pooled concentration-response curves for all three causes were almost linear without discernible thresholds. The proportion of deaths attributable to NO2 concentration above the counterfactual zero level was 1.23% (95% confidence interval 0.96% to 1.51%) across the 398 cities.

Conclusions This multilocation study provides key evidence on the independent and linear associations between short term exposure to NO2 and increased risk of total, cardiovascular, and respiratory mortality, suggesting that health benefits would be achieved by tightening the guidelines and regulatory limits of NO2.

Published Mar 24, 2021

Meng X, Liu C, Chen R, Sera F, Vicedo-Cabrera A M, Milojevic A et al. Short term associations of ambient nitrogen dioxide with daily total, cardiovascular, and respiratory mortality: multilocation analysis in 398 cities BMJ 2021; 372 :n534 doi:10.1136/bmj.n534

Fine particulate air pollution (PM2.5) exposures are linked with Alzheimer's and Parkinson's diseases (AD,PD). AD and PD neuropathological hallmarks are documented in children and young adults exposed lifelong to Metropolitan Mexico City air pollution; together with high frontal metal concentrations (especially iron)–rich nanoparticles (NP), matching air pollution combustion- and friction-derived particles. Here, we identify aberrant hyperphosphorylated tau, ɑ synuclein and TDP-43 in the brainstem of 186 Mexico City 27.29 ± 11.8y old residents. Critically, substantia nigrae (SN) pathology seen in mitochondria, endoplasmic reticulum and neuromelanin (NM) is co-associated with the abundant presence of exogenous, Fe-, Al- and Ti-rich NPs.The SN exhibits early and progressive neurovascular unit damage and mitochondria and NM are associated with metal-rich NPs including exogenous engineered Ti-rich nanorods, also identified in neuroenteric neurons. Such reactive, cytotoxic and magnetic NPs may act as catalysts for reactive oxygen species formation, altered cell signaling, and protein misfolding, aggregation and fibril formation. Hence, pervasive, airborne and environmental, metal-rich and magnetic nanoparticles may be a common denominator for quadruple misfolded protein neurodegenerative pathologies affecting urbanites from earliest childhood. The substantia nigrae is a very early target and the gastrointestinal tract (and the neuroenteric system) key brainstem portals. The ultimate neural damage and neuropathology (Alzheimer's, Parkinson's and TDP-43 pathology included) could depend on NP characteristics and the differential access and targets achieved via their portals of entry. Thus where you live, what air pollutants you are exposed to, what you are inhaling and swallowing from the air you breathe,what you eat, how you travel, and your occupational longlife history are key. Control of NP sources becomes critical.

Published Dec 1, 2020

Calderón-Garcidueñas, L., González-Maciel, A., Reynoso-Robles, R., Hammond, J., Kulesza, R., Lachmann, I., Torres-Jardón, R., Mukherjee, P. S., & Maher, B. A. (2020). Quadruple abnormal protein aggregates in brainstem pathology and exogenous metal-rich magnetic nanoparticles (and engineered Ti-rich nanorods). The substantia nigrae is a very early target in young urbanites and the gastrointestinal tract a key brainstem portal. Environmental Research, 191, 110139. https://doi.org/10.1016/J.ENVRES.2020.110139

Electricity generation is a large contributor to fine particulate matter (PM2.5) air pollution. However, the demographic distribution of the resulting exposure is largely unknown. We estimate exposures to and health impacts of PM2.5 from electricity generation in the US, for each of the seven Regional Transmission Organizations (RTOs), for each US state, by income and by race. We find that average exposures are the highest for blacks, followed by non-Latino whites. Exposures for remaining groups (e.g., Asians, Native Americans, Latinos) are somewhat lower. Disparities by race/ethnicity are observed for each income category, indicating that the racial/ethnic differences hold even after accounting for differences in income. Levels of disparity differ by state and RTO. Exposures are higher for lower-income than for higher-income, but disparities are larger by race than by income. Geographically, we observe large differences between where electricity is generated and where people experience the resulting PM2.5 health consequences; some states are net exporters of health impacts, other are net importers. For 36 US states, most of the health impacts are attributable to emissions in other states. Most of the total impacts are attributable to coal rather than other fuels.

Published Nov 20, 2020

Maninder P. S. Thind, Christopher W. Tessum, Inês L. Azevedo, and Julian D. Marshall Environmental Science & Technology 2019 53 (23), 14010-14019 DOI: 10.1021/acs.est.9b02527

Assessing whether long-term exposure to air pollution increases the severity of COVID-19 health outcomes, including death, is an important public health objective. Limitations in COVID-19 data availability and quality remain obstacles to conducting conclusive studies on this topic. At present, publicly available COVID-19 outcome data for representative populations are available only as area-level counts. Therefore, studies of long-term exposure to air pollution and COVID-19 outcomes using these data must use an ecological regression analysis, which precludes controlling for individual-level COVID-19 risk factors. We describe these challenges in the context of one of the first preliminary investigations of this question in the United States, where we found that higher historical PM2.5 exposures are positively associated with higher county-level COVID-19 mortality rates after accounting for many area-level confounders. Motivated by this study, we lay the groundwork for future research on this important topic, describe the challenges, and outline promising directions and opportunities.

Published Nov 4, 2020

Wu, X., Nethery, R. C., Sabath, M. B., Braun, D., & Dominici, F. (2020). Air pollution and COVID-19 mortality in the United States: Strengths and limitations of an ecological regression analysis. Science Advances, 6(45). doi:10.1126/sciadv.abd4049

Accumulating evidence links fine particulate matter (PM2·5) to premature mortality, cardiovascular disease, and respiratory disease. However, less is known about the influence of PM2·5 on neurological disorders. We aimed to investigate the effect of long-term PM2·5 exposure on development of Parkinson's disease or Alzheimer's disease and related dementias.
Between Jan 1, 2000, and Dec 31, 2016, of 63 038 019 individuals who were aged 65 years or older during the study period, we identified 1·0 million cases of Parkinson's disease and 3·4 million cases of Alzheimer's disease and related dementias based on primary and secondary diagnosis billing codes. For each 5 μg/m3 increase in annual PM2·5 concentrations, the HR was 1·13 (95% CI 1·12–1·14) for first hospital admission for Parkinson's disease and 1·13 (1·12–1·14) for first hospital admission for Alzheimer's disease and related dementias. For both outcomes, there was strong evidence of linearity at PM2·5 concentrations less than 16 μg/m3 (95th percentile of the PM2·5 distribution), followed by a plateaued association with increasingly larger confidence bands.

Published Oct 19, 2020

Shi, L., Wu, X., Danesh Yazdi, M., Braun, D., Abu Awad, Y., Wei, Y., Liu, P., Di, Q., Wang, Y., Schwartz, J., Dominici, F., Kioumourtzoglou, M.-A., & Zanobetti, A. (2020). Long-term effects of PM2·5 on neurological disorders in the American Medicare population: a longitudinal cohort study. The Lancet Planetary Health, 0(0). https://doi.org/10.1016/S2542-5196(20)30227-8

Childhood exposure to air pollution contributes to cardiovascular disease in adulthood. Immune and oxidative stress disturbances might mediate the effects of air pollution on the cardiovascular system, but the underlying mechanisms are poorly understood in adolescents. Therefore, we aimed to identify immune biomarkers linking air pollution exposure and blood pressure levels in adolescents.

Published Oct 16, 2020

Prunicki, M., Cauwenberghs, N., Ataam, J.A. et al. Immune biomarkers link air pollution exposure to blood pressure in adolescents. Environ Health 19, 108 (2020). https://rdcu.be/cdiQM

Fine particulate air pollution is harmful to children in myriad ways. While evidence ismounting that chronic exposures are associated with reduced academic proficiency, no research hasexamined the frequency of peak exposures. It is also unknown if pollution exposures influenceacademic proficiency to the same degree in all schools or if the level of children’s social disadvantagein schools modifies the effects, such that some schools’ academic proficiency levels are more sensitiveto exposures. We address these gaps by examining the percentage of third grade students who testedbelow the grade level in math and English language arts (ELA) in Salt Lake County, Utah primaryschools (n=156), where fine particulate pollution is a serious health threat. More frequent peakexposures were associated with reduced math and ELA proficiency, as was greater school disadvantage.High frequency peak exposures were more strongly linked to lower math proficiency in moreadvantaged schools. Findings highlight the need for policies to reduce the number of days with peakair pollution.

Published Sep 22, 2020

Mullen, Casey, et al. “Effects of PM2.5 on Third Grade Students’ Proficiency in Math and English Language Arts.” International Journal of Environmental Research and Public Health, vol. 17, no. 18, 2020, p. 6931., doi:10.3390/ijerph17186931.

The novel human coronavirus disease 2019 (COVID-19) pandemic has claimed more than 600,000 lives worldwide, causing tremendous public health, social, and economic damages. Although the risk factors of COVID-19 are still under investigation, environmental factors, such as urban air pollution, may play an important role in increasing population susceptibility to COVID-19 pathogenesis.
From January 22, 2020, to July 17, 2020, 3,659,828 COVID-19 cases and 138,552 deaths were reported in 3,076 US counties, with an overall observed case-fatality rate of 3.8%. County-level average NO2 concentrations were positively associated with both COVID-19 case-fatality rate and mortality rate in single-, bi-, and tri-pollutant models. When adjusted for co-pollutants, per interquartile-range (IQR) increase in NO2 (4.6 ppb), COVID-19 case-fatality rate and mortality rate were associated with an increase of 11.3% (95% CI 4.9%–18.2%) and 16.2% (95% CI 8.7%–24.0%), respectively. We did not observe significant associations between COVID-19 case-fatality rate and long-term exposure to PM2.5 or O3, although per IQR increase in PM2.5 (2.6 μg/m3) was marginally associated, with a 14.9% (95% CI 0.0%–31.9%) increase in COVID-19 mortality rate when adjusted for co-pollutants.

Published Sep 21, 2020

Liang, D., Shi, L., Zhao, J., Liu, P., Sarnat, J. A., Gao, S., Schwartz, J., Liu, Y., Ebelt, S. T., Scovronick, N., & Chang, H. H. (2020). Urban Air Pollution May Enhance COVID-19 Case-Fatality and Mortality Rates in the United States. The Innovation, 1(3), 100047. https://doi.org/10.1016/j.xinn.2020.100047

Background: United States government scientists estimate that COVID-19 may kill tens of thousands of Americans. Many of the pre-existing conditions that increase the risk of death in those with COVID-19 are the same diseases that are affected by long-term exposure to air pollution. We investigated whether long-term average exposure to fine particulate matter (PM2.5) is associated with an increased risk of COVID-19 death in the United States.

Design: A nationwide, cross-sectional study using county-level data.

Data sources: COVID-19 death counts were collected for more than 3,000 counties in the United States (representing 98% of the population) up to April 22, 2020 from Johns Hopkins University, Center for Systems Science and Engineering Coronavirus Resource Center.

Methods: We fit negative binomial mixed models using county-level COVID-19 deaths as the outcome and county-level long-term average of PM2.5 as the exposure. In the main analysis, we adjusted by 20 potential confounding factors including population size, age distribution, population density, time since the beginning of the outbreak, time since state’s issuance of stay-at-home order, hospital beds, number of individuals tested, weather, and socioeconomic and behavioral variables such as obesity and smoking. We included a random intercept by state to account for potential correlation in counties within the same state. We conducted more than 68 additional sensitivity analyses.

Results: We found that an increase of only 1 μg/m3 in PM2.5 is associated with an 8% increase in the COVID-19 death rate (95% confidence interval [CI]: 2%, 15%). The results were statistically significant and robust to secondary and sensitivity analyses.

Conclusions: A small increase in long-term exposure to PM2.5 leads to a large increase in the COVID-19 death rate. Despite inherent limitations of the ecological study design, our results underscore the importance of continuing to enforce existing air pollution regulations to protect human health both during and after the COVID-19 crisis. The data and code are publicly available so our analyses can be updated routinely.

Published Sep 18, 2020

Wu, X., Nethery, R. C., Sabath, B., Braun, D., & Dominici, F. (2020). Covid-19 PM2.5: a national study on long-term exposure to air pollution and COVID-19 mortality in the United States. Retrieved December 10, 2020, from A national study on long-term exposure to air pollution and COVID-19 mortality in the United States

President Trump has made dismantling environmental regulations a priority during his time in office. While some of these moves remain mired in legal uncertainty, the Trump administration has successfully unraveled the majority of Obama-era climate policies, including the Clean Power Plan, fuel economy standards for passenger vehicles, and efforts to curb potent greenhouse gases (GHGs) from refrigerants and air conditioning. Just last month, the administration eased regulations preventing methane leakage from oil and gas facilities. Rhodium Group has analyzed the isolated implications of each of these regulatory rollbacks on US GHG emissions in previous research. In this note, we examine their aggregate effect. We find that Trump’s major climate policy rollbacks have the potential to add 1.8 gigatons of CO2-equivalent to the atmosphere by 2035. This cumulative impact is equivalent to nearly one-third of all US emissions in 2019.

Published Sep 17, 2020

Hannah Pitt, Kate Larsen, M. Y. (2020). The Undoing of US Climate Policy: The Emissions Impact of Trump-Era Rollbacks. https://rhg.com/research/the-rollback-of-us-climate-policy/