Application of Earth observations and chemical transport modelling to investigate air quality and health from the city to the global scale

Ambient air pollution is responsible for 4-9 million premature deaths worldwide each year. Routine ground-based monitoring of air quality in cities is sparse and expensive and only includes a handful of pollutants. Most health risk assessment models are derived with limited health outcomes and cover a narrow range (2.4-35 µg m$^{-3}$) of fine particulate (PM$_{2.5}$) concentrations. Satellites provide daily global coverage of a dynamic range of pollutants for more than a decade and there are updated health risk assessment models that account for the increasing number of health outcomes that have been associated with air pollution and that cover a wider exposure range than previous models. In this work, the skill of satellite observations at reproducing variability in surface air quality in the UK and Indian cities was assessed. Temporal consistency (R>0.5) occurred between space-based and surface observations of nitrogen dioxide (NO$_2$) and ammonia (NH$_2$), whereas measurements of aerosol optical depth (AOD) have weak month-to-month variability (R<0.4) with surface PM$_{2.5}$, but do replicate long term trends in PM$_{2.5}$. This provided the confidence to use satellite observations to determine recent (2000s 2010s) long-term trends in NO$_2$, NH$_3$, formaldehyde (HCHO) as a marker for reactive non-methane volatile organic compounds (NMVOCs), and AOD as a marker for PM$_{2.5}$ in London and Birmingham in the UK, and Delhi and Kanpur in India. Trends in most pollutants declined in UK cities because of successful control on vehicular emissions but increased in Indian cities despite recent pollution control measures. These validated satellite observations were then used to quantify long-term trends in air quality over 46 tropical cities which are growing at an unprecedented pace (1-10 % a$^{-1}$) and that lack routine, reliable and accessible ground-based air quality measurements. Most pollutants in almost all tropical cities increased, driven almost exclusively by increase in anthropogenic activity rather than traditional biomass burning. Population exposure to hazardous pollutants PM$_{2.5}$ and NO$_2$ increased by up to 23 % a$^{-1}$ for NO$_2$ and 18 % a$^{-1}$ for PM$_{2.5}$ due to the combined increase in emerging anthropogenic air pollution and population. This suggests an impending health crisis that demands further analysis to determine the increase in health burden from increased exposure to these hazardous pollutants. This was followed by examining the health burden from exposure to PM$_{2.5}$ produced exclusively from fossil fuel combustion, a dominant and controllable anthropogenic source of PM$_{2.5}$. The health burden was estimated using the chemical transport model GEOS-Chem, validated with satellite and surface observations, and a recent meta-analysis that accounted for a wider exposure range than previous approaches. 10.2 million adult premature deaths were estimated to be from fossil fuel related PM$_{2.5}$ in 2012 with 62 % of these in China and India. These estimates are more than double than those obtained from the Global Burden of Disease and other studies because of the updated health risk assessment model and a finer spatial resolution chemical transport model. These estimates decline to 8.7 million in 2018 due to substantial decline in fossil fuel emissions in China, demonstrating the efficacy of air quality policies that target fossil fuel sources. Fossil fuel combustion can be more readily controlled than other primary and secondary sources of PM$_{2.5}$ and transitioning towards cleaner sources of energy can mitigate these premature deaths. These results highlight the immediate health crisis due to ongoing reliance on fossil fuels to complement the longer term and potentially more severe effects these will have on climate. The thesis demonstrates the application of satellite observations, ground-based measurements, chemical transport models, emission inventories and health risk assessment models and statistical techniques to determine trends and drivers of these trends in air quality in cities and estimate the health burden at different spatial scales. This is crucial information that policymakers and stakeholders require to make informed decisions and develop prescient policies

Impact of Legislated and Best Available Emission Control Measures on UK Particulate Matter Pollution, Premature Mortality, and Nitrogen-Sensitive Habitats

Past emission controls in the UK have substantially reduced precursor emissions of health-hazardous fine particles (PM2.5) and nitrogen pollution detrimental to ecosystems. Still, 79% of the UK exceeds the World Health Organization (WHO) guideline for annual mean PM2.5 of 5 μg m-3 and there is no enforcement of controls on agricultural sources of ammonia (NH3). NH3 is a phytotoxin and an increasingly large contributor to PM2.5 and nitrogen deposited to sensitive habitats. Here we use emissions projections, the GEOS-Chem model, high-resolution data sets, and contemporary exposure-risk relationships to assess potential human and ecosystem health co-benefits in 2030 relative to the present day of adopting legislated or best available emission control measures. We estimate that present-day annual adult premature mortality attributable to exposure to PM2.5 is 48,625 (95% confidence interval: 45,188-52,595), that harmful amounts of reactive nitrogen deposit to almost all (95%) sensitive habitat areas, and that 75% of ambient NH3 exceeds levels safe for bryophytes and lichens. Legal measures decrease the extent of the UK above the WHO guideline to 58% and avoid 6,800 premature deaths by 2030. This improves with best available measures to 36% of the UK and 13,300 avoided deaths. Both legal and best available measures are insufficient at reducing the extent of damage of nitrogen pollution to sensitive habitats. Far more ambitious reductions in nitrogen emissions (>80%) than is achievable with best available measures (34%) are required to halve the amount of excess nitrogen deposited to sensitive habitats

Impact of legislated and best available emission control measures on UK particulate matter pollution, premature mortality, and nitrogen-sensitive habitats

Past emission controls in the UK have substantially reduced precursor emissions of health-hazardous fine particles (PM2.5) and nitrogen pollution detrimental to ecosystems. Still, 79% of the UK exceeds the World Health Organization (WHO) guideline for annual mean PM2.5 of 5 μg m−3 and there is no enforcement of controls on agricultural sources of ammonia (NH3). NH3 is a phytotoxin and an increasingly large contributor to PM2.5 and nitrogen deposited to sensitive habitats. Here we use emissions projections, the GEOS-Chem model, high-resolution data sets, and contemporary exposure-risk relationships to assess potential human and ecosystem health co-benefits in 2030 relative to the present day of adopting legislated or best available emission control measures. We estimate that present-day annual adult premature mortality attributable to exposure to PM2.5 is 48,625 (95% confidence interval: 45,188–52,595), that harmful amounts of reactive nitrogen deposit to almost all (95%) sensitive habitat areas, and that 75% of ambient NH3 exceeds levels safe for bryophytes and lichens. Legal measures decrease the extent of the UK above the WHO guideline to 58% and avoid 6,800 premature deaths by 2030. This improves with best available measures to 36% of the UK and 13,300 avoided deaths. Both legal and best available measures are insufficient at reducing the extent of damage of nitrogen pollution to sensitive habitats. Far more ambitious reductions in nitrogen emissions (>80%) than is achievable with best available measures (34%) are required to halve the amount of excess nitrogen deposited to sensitive habitats

Long-term air quality trends in fast-growing future megacities in the tropics

info:eu-repo/semantics/nonPublishe

A space-based perspective of trends in air quality in major cities in the UK and India

info:eu-repo/semantics/nonPublishe

Rapid rise in premature mortality due to anthropogenic air pollution in fast-growing tropical cities from 2005 to 2018

Tropical cities are experiencing rapid growth but lack routine air pollution monitoring to develop prescient air quality policies. Here, we conduct targeted sampling of recent (2000s to 2010s) observations of air pollutants from space-based instruments over 46 fast-growing tropical cities. We quantify significant annual increases in nitrogen dioxide (NO2) (1 to 14%), ammonia (2 to 12%), and reactive volatile organic compounds (1 to 11%) in most cities, driven almost exclusively by emerging anthropogenic sources rather than traditional biomass burning. We estimate annual increases in urban population exposure to air pollutants of 1 to 18% for fine particles (PM2.5) and 2 to 23% for NO2 from 2005 to 2018 and attribute 180,000 (95% confidence interval: −230,000 to 590,000) additional premature deaths in 2018 (62% increase relative to 2005) to this increase in exposure. These cities are predicted to reach populations of up to 80 million people by 2100, so regulatory action targeting emerging anthropogenic sources is urgently needed

Long-term trends in air quality in major cities in the UK and India: a view from space

Abstract. Air quality networks in cities can be costly and inconsistent and typicallymonitor a few pollutants. Space-based instruments provide global coveragespanning more than a decade to determine trends in air quality, augmentingsurface networks. Here we target cities in the UK (London and Birmingham)and India (Delhi and Kanpur) and use observations of nitrogen dioxide(NO2) from the Ozone Monitoring Instrument (OMI), ammonia (NH3)from the Infrared Atmospheric Sounding Interferometer (IASI), formaldehyde(HCHO) from OMI as a proxy for non-methane volatile organic compounds(NMVOCs), and aerosol optical depth (AOD) from the Moderate ResolutionImaging Spectroradiometer (MODIS) for PM2.5. We assess the skill ofthese products at reproducing monthly variability in surface concentrationsof air pollutants where available. We find temporal consistency betweencolumn and surface NO2 in cities in the UK and India (R = 0.5–0.7)and NH3 at two of three rural sites in the UK (R = 0.5–0.7) but notbetween AOD and surface PM2.5 (R  9 % a−1) increasein reactive NMVOCs in London. The cause for this rapid increase isuncertain but may reflect the increased contribution of oxygenated volatile organic compounds (VOCs) fromhousehold products, the food and beverage industry, and domestic woodburning, with implications for the formation of ozone in a VOC-limited city.info:eu-repo/semantics/publishe

Burden of disease scenarios for 204 countries and territories, 2022–2050: a forecasting analysis for the Global Burden of Disease Study 2021

BackgroundFuture trends in disease burden and drivers of health are of great interest to policy makers and the public at large. This information can be used for policy and long-term health investment, planning, and prioritisation. We have expanded and improved upon previous forecasts produced as part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) and provide a reference forecast (the most likely future), and alternative scenarios assessing disease burden trajectories if selected sets of risk factors were eliminated from current levels by 2050.MethodsUsing forecasts of major drivers of health such as the Socio-demographic Index (SDI; a composite measure of lag-distributed income per capita, mean years of education, and total fertility under 25 years of age) and the full set of risk factor exposures captured by GBD, we provide cause-specific forecasts of mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) by age and sex from 2022 to 2050 for 204 countries and territories, 21 GBD regions, seven super-regions, and the world. All analyses were done at the cause-specific level so that only risk factors deemed causal by the GBD comparative risk assessment influenced future trajectories of mortality for each disease. Cause-specific mortality was modelled using mixed-effects models with SDI and time as the main covariates, and the combined impact of causal risk factors as an offset in the model. At the all-cause mortality level, we captured unexplained variation by modelling residuals with an autoregressive integrated moving average model with drift attenuation. These all-cause forecasts constrained the cause-specific forecasts at successively deeper levels of the GBD cause hierarchy using cascading mortality models, thus ensuring a robust estimate of cause-specific mortality. For non-fatal measures (eg, low back pain), incidence and prevalence were forecasted from mixed-effects models with SDI as the main covariate, and YLDs were computed from the resulting prevalence forecasts and average disability weights from GBD. Alternative future scenarios were constructed by replacing appropriate reference trajectories for risk factors with hypothetical trajectories of gradual elimination of risk factor exposure from current levels to 2050. The scenarios were constructed from various sets of risk factors: environmental risks (Safer Environment scenario), risks associated with communicable, maternal, neonatal, and nutritional diseases (CMNNs; Improved Childhood Nutrition and Vaccination scenario), risks associated with major non-communicable diseases (NCDs; Improved Behavioural and Metabolic Risks scenario), and the combined effects of these three scenarios. Using the Shared Socioeconomic Pathways climate scenarios SSP2-4.5 as reference and SSP1-1.9 as an optimistic alternative in the Safer Environment scenario, we accounted for climate change impact on health by using the most recent Intergovernmental Panel on Climate Change temperature forecasts and published trajectories of ambient air pollution for the same two scenarios. Life expectancy and healthy life expectancy were computed using standard methods. The forecasting framework includes computing the age-sex-specific future population for each location and separately for each scenario. 95% uncertainty intervals (UIs) for each individual future estimate were derived from the 2·5th and 97·5th percentiles of distributions generated from propagating 500 draws through the multistage computational pipeline.FindingsIn the reference scenario forecast, global and super-regional life expectancy increased from 2022 to 2050, but improvement was at a slower pace than in the three decades preceding the COVID-19 pandemic (beginning in 2020). Gains in future life expectancy were forecasted to be greatest in super-regions with comparatively low life expectancies (such as sub-Saharan Africa) compared with super-regions with higher life expectancies (such as the high-income super-region), leading to a trend towards convergence in life expectancy across locations between now and 2050. At the super-region level, forecasted healthy life expectancy patterns were similar to those of life expectancies. Forecasts for the reference scenario found that health will improve in the coming decades, with all-cause age-standardised DALY rates decreasing in every GBD super-region. The total DALY burden measured in counts, however, will increase in every super-region, largely a function of population ageing and growth. We also forecasted that both DALY counts and age-standardised DALY rates will continue to shift from CMNNs to NCDs, with the most pronounced shifts occurring in sub-Saharan Africa (60·1% [95% UI 56·8–63·1] of DALYs were from CMNNs in 2022 compared with 35·8% [31·0–45·0] in 2050) and south Asia (31·7% [29·2–34·1] to 15·5% [13·7–17·5]). This shift is reflected in the leading global causes of DALYs, with the top four causes in 2050 being ischaemic heart disease, stroke, diabetes, and chronic obstructive pulmonary disease, compared with 2022, with ischaemic heart disease, neonatal disorders, stroke, and lower respiratory infections at the top. The global proportion of DALYs due to YLDs likewise increased from 33·8% (27·4–40·3) to 41·1% (33·9–48·1) from 2022 to 2050, demonstrating an important shift in overall disease burden towards morbidity and away from premature death. The largest shift of this kind was forecasted for sub-Saharan Africa, from 20·1% (15·6–25·3) of DALYs due to YLDs in 2022 to 35·6% (26·5–43·0) in 2050. In the assessment of alternative future scenarios, the combined effects of the scenarios (Safer Environment, Improved Childhood Nutrition and Vaccination, and Improved Behavioural and Metabolic Risks scenarios) demonstrated an important decrease in the global burden of DALYs in 2050 of 15·4% (13·5–17·5) compared with the reference scenario, with decreases across super-regions ranging from 10·4% (9·7–11·3) in the high-income super-region to 23·9% (20·7–27·3) in north Africa and the Middle East. The Safer Environment scenario had its largest decrease in sub-Saharan Africa (5·2% [3·5–6·8]), the Improved Behavioural and Metabolic Risks scenario in north Africa and the Middle East (23·2% [20·2–26·5]), and the Improved Nutrition and Vaccination scenario in sub-Saharan Africa (2·0% [–0·6 to 3·6]).InterpretationGlobally, life expectancy and age-standardised disease burden were forecasted to improve between 2022 and 2050, with the majority of the burden continuing to shift from CMNNs to NCDs. That said, continued progress on reducing the CMNN disease burden will be dependent on maintaining investment in and policy emphasis on CMNN disease prevention and treatment. Mostly due to growth and ageing of populations, the number of deaths and DALYs due to all causes combined will generally increase. By constructing alternative future scenarios wherein certain risk exposures are eliminated by 2050, we have shown that opportunities exist to substantially improve health outcomes in the future through concerted efforts to prevent exposure to well established risk factors and to expand access to key health interventions.FundingBill & Melinda Gates Foundation.</p