Changes in ozone and PM2.5 in Europe during the period of 1990-2030: Role of reductions in land and ship emissions

Fires as a source of annual ambient PM2.5 exposure and chronic health impacts in Europe

Chronic exposure to ambient PM2.5 is the largest environmental health risk in Europe. We used a chemical transport model and recent exposure response functions to simulate ambient PM2.5, contribution from fires and related health impacts over Europe from 1990 to 2019. Our estimation indicates that the excess death burden from exposure to ambient PM2.5 declined across Europe at a rate of 10,000 deaths per year, from 0.57 million (95 % confidence intervals: 0.44-0.75 million) in 1990 to 0.28 million (0.19-0.42 million) in the specified period. Among these excess deaths, approximately 99 % were among adults, while only around 1 % occurred among children. Our findings reveal a steady increase in fire mortality fractions (excess deaths from fires per 1000 deaths from ambient PM2.5) from 2 in 1990 to 13 in 2019. Notably, countries in Eastern Europe exhibited significantly higher fire mortality fractions and experienced more pronounced increases compared to those in Western and Central Europe. We performed sensitivity analyses by considering fire PM2.5 to be more toxic as compared to other sources, as indicated by recent studies. By considering fire PM2.5 to be more toxic than other PM2.5 sources results in an increased relative contribution of fires to excess deaths, reaching 2.5-13 % in 2019. Our results indicate the requirement of larger mitigation and adaptation efforts and more sustainable forest management policies to avert the rising health burden from fires.

Impact of long-term exposure to ambient ozone on lung function over a course of 20 years (The ECRHS study): a prospective cohort study in adults

Background

While the adverse effects of short-term ambient ozone exposure on lung function are well-documented, the impact of long-term exposure remains poorly understood, especially in adults.

Methods

We aimed to investigate the association between long-term ozone exposure and lung function decline. The 3014 participants were drawn from 17 centers across eight countries, all of which were from the European Community Respiratory Health Survey (ECRHS). Spirometry was conducted to measure pre-bronchodilation forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) at approximately 35, 44, and 55 years of age. We assigned annual mean values of daily maximum running 8-h average ozone concentrations to individual residential addresses. Adjustments were made for PM2.5, NO2, and greenness. To capture the ozone-related change in spirometric parameters, our linear mixed effects regression models included an interaction term between long-term ozone exposure and age.

Findings

Mean ambient ozone concentrations were approximately 65 μg/m³. A one interquartile range increase of 7 μg/m³ in ozone was associated with a faster decline in FEV1 of -2.08 mL/year (95% confidence interval: -2.79, -1.36) and in FVC of -2.86 mL/year (-3.73, -1.99) mL/year over the study period. Associations were robust after adjusting for PM2.5, NO2, and greenness. The associations were more pronounced in residents of northern Europe and individuals who were older at baseline. No consistent associations were detected with the FEV1/FVC ratio.

Interpretation

Long-term exposure to elevated ambient ozone concentrations was associated with a faster decline of spirometric lung function among middle-aged European adults over a 20-year period.

Funding

German Research Foundation.

Ante- and post-mortem cellular injury dynamics in hybrid poplar foliage as a function of phytotoxic O3 dose

After reaching phytotoxic levels during the last century, tropospheric ozone (O3) pollution is likely to remain a major concern in the coming decades. Despite similar injury processes, there is astounding interspecific-and sometimes intraspecific-foliar symptom variability, which may be related to spatial and temporal variation in injury dynamics. After characterizing the dynamics of physiological responses and O3 injury in the foliage of hybrid poplar in an earlier study, here we investigated the dynamics of changes in the cell structure occurring in the mesophyll as a function of O3 treatment, time, phytotoxic O3 dose (POD0), leaf developmental stage, and mesophyll layer. While the number of Hypersensitive Response-like (HR-like) lesions increased with higher O3 concentrations and POD0, especially in older leaves, most structural HR-like markers developed after cell death, independent of the experimental factors. The pace of degenerative Accelerated Cell Senescence (ACS) responses depended closely on the O3 concentration and POD0, in interaction with leaf age. Changes in total chlorophyll content, plastoglobuli and chloroplast shape pointed to thylakoid membranes in chloroplasts as being especially sensitive to O3 stress. Hence, our study demonstrates that early HR-like markers can provide reasonably specific, sensitive and reliable quantitative structural estimates of O3 stress for e.g. risk assessment studies, especially if they are associated with degenerative and thylakoid-related injury in chloroplasts from mesophyll.

Low sensitivity of Pinus mugo to surface ozone pollution in the subalpine zone of continental Europe

High altitudes have been exposed to enhanced levels of surface ozone (O₃) concentrations over recent decades compared to the pre-industrial era. The responses of vegetation to this toxic pollutant are species-specific and depend on the climate conditions. In this paper, we explored the reaction of Pinus mugo (P. mugo) to O₃-induced stress in the continental climate of an ozone-rich mountain area in the High Tatra Mountains (Western Carpathians). The effects of O₃ doses modelled by a deposition model, O₃ concentrations and other factors on P. mugo were identified from (a) satellite-based data via NDVI (normalised differenced vegetation index) over 2000-2020 and (b) visible injury on needle samples gathered from P. mugo individuals at ground-truth sites in 2019 and 2020. Analysing the NDVI trend, we observed non-significant changes (p > 0.05) in the greenness of P. mugo despite growing in an environment with the average seasonal O₃ concentration around 51.6 ppbv, the maximum hourly concentrations more than 90 ppbv and increasing trend of O₃ doses by 0.1 mmol m^-2 PLA (plant leaf area) year^-1. The visible O₃ injury of samples collected at study sites was low (mean injury observed on 1-10% of needles' surface), and the symptoms of injury caused by other biotic and abiotic factors prevailed over those caused by O₃. In addition, the correlation analyses between NDVI and the climatic factors indicated a significant (p < 0.05) and positive relationship with photosynthetic active radiation (R = 0.45) in July, and with stomatal conductance (R = 0.52) and temperature factor (R = 0.43) in August. Therefore, we concluded that the positive effect of climate conditions, which support the growth processes of P. mugo, may suppress the negative effect of the mean O₃ doses of 17.8 mmol m^-2 PLA accumulated over the growing season.

Health risk and disease burden attributable to long-term global fine-mode particles

Particulate matter 2.5 (PM_2.5) pollution has long been a global environmental problem and still poses a great threat to public health. This study investigates global spatiotemporal variations in PM_2.5 using the newly developed satellite-derived PM_2.5 dataset from 1998 to 2018. An integrated exposure-response (IER) model was employed to examine the characteristics of PM_2.5-related deaths caused by chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD), lung cancer (LC), and stroke in adults (age≥25), as well as lower respiratory infection (LRI) in children (age≤5). The results showed that high annual PM_2.5 concentrations were observed mainly in East Asia and South Asia. Over the 19-year period, PM_2.5 concentrations constantly decreased in developed regions, but increased in most developing regions. Approximately 84% of the population lived in regions where PM_2.5 concentrations exceeded 10 μg/m³. Meanwhile, the vast majority of the population (>60%) in East and South Asia was consistently exposed to PM_2.5 levels above 35 μg/m³. PM_2.5 exposure was linked to 3.38 (95% UI: 3.05-3.70) million premature deaths globally in 2000, a number that increased to 4.11 (95% UI: 3.55-4.69) million in 2018. Premature deaths related to PM_2.5 accounted for 6.54%-7.79% of the total cause of deaths worldwide, with a peak in 2011. Furthermore, developing regions contributed to the majority (85.95%-95.06%) of PM_2.5-related deaths worldwide, and the three highest-ranking regions were East Asia, South Asia, and Southeast Asia. Globally, IHD and stroke were the two main contributors to total PM_2.5-related deaths, followed by COPD, LC, and LRI.

Temporal Changes in Ozone Concentrations and Their Impact on Vegetation

Tropospheric concentrations of phytotoxic ozone (O3) have undergone a great increase from preindustrial 10–15 ppbv to a present-day concentration of 35–40 ppbv in large parts of the industrialised world due to increased emissions of O3 precursors including NOx, CO, CH4 and volatile organic compounds. The rate of increase in O3 concentration ranges between 1 ppbv per decade in remote locations of the Southern hemisphere and 5 ppbv per decade in the Northern hemisphere, where largest sources of O3 precursors are located. Molecules of O3 penetrating into the leaves through the stomatal apertures trigger the formation of reactive oxygen species, leading thus to the damage of the photosynthetic apparatus. Accordingly, it is assumed, that O3 increase reduces the terrestrial carbon uptake relative to the preindustrial era. Here we summarise the results of previous manipulative experiments in laboratory growth cabinets, field open-top chambers and free-air systems together with O3 flux measurements under natural growth conditions. In particular, we focus on leaf-level physiological responses in trees, variability in stomatal O3 flux and changes in carbon fluxes and biomass production in forest stands. As the results reported in the literature are highly variable, ranging from negligible to severe declines in photosynthetic carbon uptake, we also discuss the possible interactions of O3 with other environmental factors including solar radiation, drought, temperature and nitrogen deposition. Those factors were found to have great potential to modulate stomata openness and O3 fluxes.