Gongda Lu

and 6 more

Cities in South and Southeast Asia are developing rapidly without routine, up-to-date knowledge of air pollutant precursor emissions. This data deficit can potentially be addressed for nitrogen oxides (NOx) by deriving city NOx emissions from satellite observations of nitrogen dioxide (NO2) sampled under windy conditions. NO2 plumes of isolated cities are aligned along a consistent wind-rotated direction and a best-fit Gaussian is applied to estimate emissions. This approach currently relies on non-standardized selection of the area to sample around the city centre and Gaussian fits often fail or yield non-physical parameters. Here, we automate this approach by defining many (54) sampling areas that we test with TROPOspheric Monitoring Instrument (TROPOMI) NO2 observations for 2019 over 19 cities in South and Southeast Asia. Our approach is efficient, adaptable to many cities, standardizes and eliminates sensitivity of the Gaussian fit to sampling area choice, and increases success of deriving annual emissions from 40-60% with one sampling area to 100% (all 19 cities) with 54. The annual emissions we estimate range from 16±5 mol s-1 for Yangon (Myanmar) and Bangalore (India) to 125±41 mol s-1 for Dhaka (Bangladesh). With the enhanced success of our approach, we find evidence from comparison of our top-down emissions to past studies and to inventory estimates that the wind rotation and EMG fit approach may be biased, as it does not adequately account for spatial and seasonal variability in NOx photochemistry. Further methodological development is needed to enhance its accuracy and to exploit it to derive sub-annual emissions.

Eloise A. Marais

and 6 more

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 datasets, and contemporary relationships between exposure and risk of harm to assess the potential human and ecosystem health co-benefits in 2030 relative to the present day of adopting legally required or best available emission control measures. We estimate that present-day annual adult premature mortality attributable to exposure to PM2.5 is 48,625, 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. 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, as most nitrogen emitted in the UK is exported offshore. Far more ambitious reductions in nitrogen emissions (>80%) than is achievable with best available measures (34%) are required to halve excess nitrogen deposition to sensitive habitats.

Eloise Ann Marais

and 10 more

Karn Vohra

and 6 more

Robert G. Ryan

and 3 more

Detailed examination of the impact of modern space launches on the Earth’s atmosphere is crucial, given booming investment in the space industry and an anticipated space tourism era. We develop air pollutant emissions inventories for rocket launches and re-entry of reusable components and debris in 2019 and for a speculative space tourism scenario based on the recent billionaire space race. This we include in the global GEOS-Chem model coupled to a radiative transfer model to determine the influence on stratospheric ozone (O3) and climate. Due to recent surge in re-entering debris and reusable components, nitrogen oxides from ablation and chlorine from solid fuels contribute equally to all stratospheric O3 depletion by contemporary rockets. Decline in global stratospheric O3 is small (0.01%), but reaches 0.15% in the upper stratosphere (~5 hPa, 40 km) in spring at 60-90°N after a decade of sustained 5.6% a-1 growth in 2019 launches and re-entries. This increases to 0.22% with a decade of emissions from space tourism rockets, undermining O3 recovery achieved with the Montreal Protocol. Rocket emissions of black carbon (BC) produce substantial global mean warming of 8 mW m-2 after just 3 years of routine space tourism launches. This is a much greater contribution to global radiative forcing (6%) than emissions (0.02%) of all other BC sources, as warming per unit mass emitted is ~500 times more than surface and aviation sources. The O3 damage and warming we estimate should motivate regulation of an industry poised for rapid growth.