Measuring the ISM Content of Nearby, Luminous, Type 1 and Type 2 QSOs through CO and [C II]

arXiv (Cornell University) · 2024

• Astrophysics
• Physics
• Astronomy

We present observations of CO(1--0) and CO(2--1) lines from the Institut de radioastronomie millimétrique (IRAM) 30m telescope toward 20 nearby, optically luminous type 2 quasars (QSO2s) and observations of [C II] 158$μ$m line from the Stratospheric Observatory For Infrared Astronomy (SOFIA) for 5 QSO2s in the CO sample and 5 type 1 quasars (QSO1s). In the traditional evolutionary scenario explaining different types of QSOs, obscured QSO2s emerge from gas-rich mergers observed as luminous infrared galaxies (LIRGs) and then turn into unobscured QSO1s as the black holes clear out the obscuring material in a blow-out phase. We test the validity of this theoretical prediction by comparing the gas fractions and star formation efficiencies among LIRGs and QSOs. We find that CO luminosity, CO-derived gas masses and gas fractions in QSO1s are consistent with those estimated for QSO2s, while LIRGs exhibit a closer resemblance to QSO2s in terms of CO-derived gas masses and gas fractions. Comparisons between [C II] luminosity and star formation tracers such as the CO and infrared luminosity imply additional sources of [C II] emission in QSO1s likely tracing neutral atomic or ionized gas with the caveat of a small sample size. All three types of galaxies have statistically indistinguishable distributions of star formation efficiency. Our results are consistent with part of the evolutionary scenario where nearby QSO2s could emerge from LIRGs, but they may not be the precursors of nearby QSO1s.

Air quality policy should quantify effects on disparities

Science · 2023 · 63 citations

• Environmental science
• Environmental health
• Geography

New tools can guide US policies to better target and reduce racial and socioeconomic disparities in air pollution exposure

Sources of ambient PM2.5 exposure in 96 global cities

Atmospheric Environment · 2022 · 54 citations

• Environmental science
• Geography
• Environmental protection

exposure caused by within-city emissions varies widely (μ = 37%; σ = 22%) and is not well-explained by surrounding population density. The list of most-important sources also varies by city. Compared to a more mechanistically detailed model, InMAP predicts urban measured concentrations with lower bias and error but also lower correlation. Predictive accuracy in urban areas is not particularly high with either model, suggesting an opportunity for improving global urban air emission inventories. We expect the results herein can be useful as a screening tool for policy options and, in the absence of available resources for further analysis, to inform policy action to improve public health.

Historical Redlining Is Associated with Present-Day Air Pollution Disparities in U.S. Cities

Environmental Science & Technology Letters · 2022 · 425 citations

• Political Science
• Geography
• Demographic economics

are substantially larger by historical HOLC grade than they are by race and ethnicity. However, within each HOLC grade, racial and ethnic air pollution exposure disparities persist, indicating that redlining was only one of the many racially discriminatory policies that impacted communities. Our findings illustrate how redlining, a nearly 80-year-old racially discriminatory policy, continues to shape systemic environmental exposure disparities in the United States.

PM _2.5 polluters disproportionately and systemically affect people of color in the United States

Science Advances · 2021 · 574 citations

• Political Science
• Geography
• Environmental health

exposure disparity experienced by people of color. We identify the most inequitable emission source types by state and city, thereby highlighting potential opportunities for addressing this persistent environmental inequity.

The food we eat, the air we breathe: a review of the fine particulate matter-induced air quality health impacts of the global food system

Environmental Research Letters · 2021 · 56 citations

• Environmental science
• Environmental health
• Environmental protection

The global food system is essential for the health and wellbeing of society, but is also a major cause of environmental damage. Some impacts, such as on climate change, have been the subject of intense recent inquiry, but others, such as on air quality, are not as well understood. Here, we systematically synthesize the literature to identify the impacts on ambient PM _2.5 (particulate matter with diameter ⩽2.5 μ m), which is the strongest contributor to premature mortality from exposure to air pollution. Our analysis indicates that the life-cycle of the global food system (pre-production, production, post-production, consumption and waste management) accounts for 58% of anthropogenic, global emissions of primary PM _2.5 , 72% of ammonia (NH _3 ), 13% of nitrogen oxides (NO _x ), 9% of sulfur dioxide (SO _2 ), and 19% of non-methane volatile organic compounds (NMVOC). These emissions result in at least 890 000 ambient PM _2.5 -related deaths, which is equivalent to 23% of ambient PM _2.5 -related deaths reported in the Global Burden of Disease Study 2015. Predominant contributors include livestock and crop production, which contribute >50% of food-related NH _3 emissions, and land-use change and waste burning, which contribute up to 95% of food-related primary PM _2.5 emissions. These findings are largely underestimated given the paucity of data from the post-production and consumption stages, total underestimates in NH _3 emissions, lack of sector-scale analysis of PM _2.5 -related deaths in South America and Africa, and uncertainties in integrated exposure-response functions. In addition, we identify mitigation opportunities—including shifts in food demand, changes in agricultural practices, the adoption of clean and low-energy technologies, and policy actions—that can facilitate meeting food demand with minimal PM _2.5 impacts. Further research is required to resolve sectoral-scale, region-specific contributions to PM _2.5 -related deaths, and assess the efficiency of mitigation strategies. Our review is positioned to inform stakeholders, including scientists, engineers, policymakers, farmers and the public, of the health impacts of reduced air quality resulting from the global food system.

Air quality–related health damages of food

Proceedings of the National Academy of Sciences · 2021 · 182 citations

• Political Science
• Environmental health
• Business

emissions from tillage, field burning, livestock dust, and machinery. Dietary shifts toward more plant-based foods that maintain protein intake and other nutritional needs could reduce agricultural air quality-related mortality by 68 to 83%. In sum, improved livestock and fertilization practices, and dietary shifts could greatly decrease the health impacts of agriculture caused by its contribution to reduced air quality.

Cardiopulmonary Mortality and Fine Particulate Air Pollution by Species and Source in a National U.S. Cohort

Environmental Science & Technology · 2021 · 62 citations

• Environmental science
• Environmental chemistry
• Toxicology

mortality relationship. With further validation, these findings could facilitate targeted pollution regulations that more efficiently reduce air pollution mortality.

Disparities in Air Pollution Exposure in the United States by Race/Ethnicity and Income, 1990–2010

Environmental Health Perspectives · 2021 · 373 citations

• Political Science
• Demography
• Environmental health

BACKGROUND: Few studies have investigated air pollution exposure disparities by race/ethnicity and income across criteria air pollutants, locations, or time. OBJECTIVE: The objective of this study was to quantify exposure disparities by race/ethnicity and income throughout the contiguous United States for six criteria air pollutants, during the period 1990 to 2010. METHODS: ). We used census data for demographic information and a national empirical model for ambient air pollution levels. RESULTS: reduction). DISCUSSION: As air pollution concentrations declined during the period 1990 to 2010, absolute (and to a lesser extent, relative) racial/ethnic exposure disparities also declined. However, in 2010, racial/ethnic exposure disparities remained across income levels, in urban and rural areas, and in all states, for multiple pollutants. https://doi.org/10.1289/EHP8584.

In-use emissions from biomass and LPG stoves measured during a large, multi-year cookstove intervention study in rural India

The Science of The Total Environment · 2020 · 51 citations

• Environmental science
• Waste management
• Environmental engineering