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•Temperature and stagnation increased and precipitation less frequent, mainly in warmer months.•Strong variability of weather effects for different regions, seasons and ...pollutants.•Regional weather penalties up to 0.883 μg⋅m−3⋅yr−1 (95% CI: 0.834, 1.000) for PM10.•3220 deaths (CI: 626, 5813) due to weather penalties on PM10 in 25 years.•10% greater air quality-related health benefits if weather had remained constant.
Climate change is a major public health concern. In addition to its direct impacts on temperature patterns and extreme weather events, climate change affects public health indirectly through its influence on air quality. Pollution trends are not only affected by emissions changes but also by weather changes. In this paper we analyze air quality trends in Spain of important air pollutants (C6H6, CO, NO2, NOx, O3, PM10, PM2.5, and SO2) recorded during the last 25 years, from 1993 to 2017. We found substantial reductions in ambient concentration levels for all the pollutants studied except for O3. To assess the influence of recent weather changes on air quality trends we applied generalized additive models (GAMs) using nonparametric smoothing; with and without adjusting for weather parameters including temperature, wind speed, humidity and precipitation frequency. The difference of annual slopes estimated by the models without and with adjusting for these meteorological variables represents the impact of weather changes on pollutant trends, i.e. the ‘weather penalty’. The analyses were seasonally and geographically stratified to account for temporal and regional differences across Spain. The results were meta-analyzed to estimate weather penalties on ambient concentration trends at a national level as well as the impact on mortality for the most relevant pollutants. We found significant penalties for most pollutants, implying that air quality would have improved even more during our study period if weather conditions had remained constant. The largest weather influences were found for PM10, with seasonal penalties up to 22 μg⋅m−3 accumulated over the 25-year period in some regions. The national meta-analysis shows penalties of 0.060 μg⋅m−3 per year (95% Confidence Interval, CI: 0.004, 0.116) in cold months and 0.127 μg⋅m−3 per year (95% CI: 0.089, 0.164) in warm months. Penalties of this magnitude would correspond to 129 annual deaths (95% CI: 25, 233), i.e. approximately 3200 deaths over the 25-year period in Spain. According to our results, the health benefits of recent emission abatements for this pollutant in Spain would have been up to 10% greater if weather conditions had remained constant during the last 25 years.
Abstract
Traffic-related air quality issues remain in urban areas worldwide. For this reason, there is an increasing need to estimate the contribution of road traffic to atmospheric emissions at ...local level with high temporal and spatial resolution. Modal models compute emission rates as a function of specific engine or vehicle operating conditions at the highest resolution (seconds). They can be applied for microscale studies being a cost-effective tool to emulate differences in emissions levels in road networks. Two modal emission models, the Australian PΔP (Power-delta-Power) and the simplified version of the European PHEM (Passenger Car and Heavy-duty Emission Model), PHEM-light model, have been used. Also, a comparison to the cycle-variable emission model VERSIT+
micro
(Netherlands organisation for applied scientific research state of the art traffic emission model) has been performed. For the comparison of both modal models, the main variables involved in traffic emission calculation were identified. 1 Hz speed-time profiles for individual vehicles were generated with the traffic microsimulation model VISSIM (Vehrkehr in Statden SIMulation) for different traffic conditions. To understand the response of modal models, detailed estimations of NO
X
emissions and fuel consumption were compared for different vehicle classes. Instantaneous emission profiles for individual driving patterns are highly sensitive to speed-acceleration profiles, vehicle mass, and road gradient, which are essential variables for the emission calculation. Although there are differences between European and Australian models, engine power and load were used to map vehicle classes for a more consistent comparison. It is essential to accurately define these parameters for each vehicle class in addition to detailed driving patterns to obtain high-resolution emissions estimates. In this sense, a larger number of vehicle classes included in the model provides more flexibility to develop representative emissions estimates. Emission predictions between modal models were reasonably consistent presenting larger differences with the cycle-variable model, despite both modal models being based on different on-road fleet measurements. In conclusion, analysing emission estimations for different traffic conditions demonstrates the importance of an accurate definition of the model parameters for a specific vehicle fleet.
This study explores the potential correlation between income and exposure to air pollution for the city of Madrid, Spain and its neighboring municipalities. Madrid is a well-known European air ...pollution hotspot with a high mortality burden attributable to nitrogen dioxide (NO2) and fine particulate matter (PM2.5). Statistical analyses were carried out using electoral district level data on gross household income (GHI), and NO2 and PM2.5 concentrations in air obtained from a mesoscale air quality model for the study area. We applied linear regression, bivariate spatial correlation analysis, spatial autoregression and geographically weighted regression to explore the relationship between contaminants and income. Three different strategies were adopted to harmonize data for analysis. While some strategies suggested a link between income and air pollution, others did not, highlighting the need for multiple different approaches where uncertainty is high. Our findings offer important lessons for future spatial geographical studies of air pollution in cities worldwide. In particular we highlight the limitations of census-scale socio-economic data and the lack of non-model derived high-resolution air quality measurement data for many cities and offers lessons for policy makers on improving the integration of these types of essential public information.
The oceans are the main source of natural halogen and sulfur compounds, which have a significant influence on the oxidizing capacity of the marine atmosphere; however, their impact on the air quality ...of coastal cities is currently unknown. We explore the effect of marine halogens (Cl, Br and I) and dimethyl sulfide (DMS) on the air quality of a large coastal city through a set of high-resolution (4-km) air quality simulations for the urban area of Los Angeles, US, using the Community Multiscale Air Quality (CMAQ model). The results indicate that marine halogen emissions decrease ozone and nitrogen dioxide levels up to 5ppbv and 2.5ppbv, respectively, in the city of Los Angeles. Previous studies suggested that the inclusion of chlorine in air quality models leads to the generation of ozone in urban areas through photolysis of nitryl chloride (ClNO2). However, we find that when considering the chemistry of Cl, Br and I together the net effect is a reduction of surface ozone concentrations. Furthermore, combined ocean emissions of halogens and DMS cause substantial changes in the levels of key urban atmospheric oxidants such as OH, HO2 and NO3, and in the composition and mass of fine particles. Although the levels of ozone, NO3 and HOx are reduced, we find a 10% increase in secondary organic aerosol (SOA) mean concentration, attributed to the increase in aerosol acidity and sulfate aerosol formation when combining DMS and bromine. Therefore, this new pathway for enhanced SOA formation may potentially help with current model under predictions of urban SOA. Although further observations and research are needed to establish these preliminary conclusions, this first city-scale investigation suggests that the inclusion of oceanic halogens and DMS in air quality models may improve regional air quality predictions over coastal cities around the world.
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•Natural marine emissions (Cl, Br, I and DMS) included in CMAQ simulations over LA.•Oceanic halogens and DMS may play an important role on coastal urban areas.•Substantial changes in the levels of key urban atmospheric oxidants (OH, HO2 and NO3).•O3 and NO2 ambient levels decreased by 5ppbv and 2.5ppbv in Los Angeles city.•10% increase in secondary organic aerosol (SOA) due to dimethyl sulphide (DMS).
Health effects linked to exposure to high air pollutant levels have been described in depth, and many recent epidemiologic studies have also consistently reported positive associations between ...exposure to air pollutants at low concentrations (particularly PM2.5) and adverse health outcomes. To estimate the number of avoidable deaths associated with reducing PM2.5 levels in Spain. For exposure assessment, we used the US Environmental Protection Agency's Community Multiscale Air Quality model to simulate air pollution levels with a spatial resolution of 18x18km super(2). Two different scenarios were compared, namely, a baseline 2004 scenario based on Spain's National Emissions Inventory and a projected 2011 scenario in which a reduction in PM2.5 was estimated on the basis of the benefits that might be attained if specific air quality policies were implemented. Using an 18x18km super(2) grid, air pollution data were estimated for the entire Iberian Peninsula, the Balearic Islands, Ceuta and Melilla. For these strata, crude all-cause mortality rates (ICD-10: A00-Y98) were then calculated for the over-30 and 25-74 age groups, taking into account the 2004 population figures corresponding to these same age groups, selected in accordance with the concentration-response functions (Pope CA 3rd, Burnett RT, Thun MJ, Calle EE, Krewski D, Ito K et al. Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. JAMA 2002; 287:1132-41; Laden F, Schwartz J, Speizer FE, Dockery DW. Reduction in fine particulate air pollution and mortality: extended follow-up of the Harvard Six Cities study. Am J Respir Crit Care Med 2006; 173:667-72.). Health impacts were assessed using the Environmental Benefits Mapping and Analysis Program (BenMAP). Air quality improvement was defined as an average annual reduction of 0.7 mu g/m super(3) in PM2.5 levels. Using long-term health impact assessment analysis, we estimated that 1720 (673-2760) all-cause deaths (6 per 100,000 population) in the over-30 age group and 1450 (780-2108) all-cause deaths (5 per 100,000 population) in the 25-74 age group could be prevented annually. The results showed the potential benefits in general mortality which could be expected if pollution control policies were successfully implemented by 2011. A specifically adapted BenMAP could be used as a tool for estimating health impacts associated with changes in air pollution in Spain.
The coronavirus disease (COVID) lockdown was implemented in 2020, which included harsh restrictions on the amount of traffic. As a consequence, a low-emission scenario that could only be simulated ...before, actually occurred. This constituted a unique and valuable opportunity to study the effect of air quality pollutant concentrations. Although a direct comparison between the observed measured values given by reference air quality stations (AQSs) and values from before the COVID lockdown provides an idea of the pollution reduction, it cannot be separated from the meteorology, and hence, those studies could be misleading. This study used the approach of modeling a normal business day using both air quality and meteorological data from 2017 to 2019 to train machine-learning models to be able to predict what concentration of the three most concerning pollutants (NO
2
, O
3
, and PM
10
) would be given by the meteorological conditions and the time of the year. The XGBoost and LightGBM gradient boosting decision tree-based models were applied to the time series recorded in Madrid and used to predict the expected concentrations in 2020 if no restrictions had been made. The predictions could then be compared to the real observed AQS data to determine the meteorological normalized reductions. The results showed around a 60% reduction in the NO
2
at the three types of AQSs (traffic, suburban, and background) during the most restrictive months of the pandemic. The O
3
concentration showed a different behavior depending on the type of AQS, pointing to changes in the regime of other pollutants, such as VOCs. The PM
10
was the most difficult case to analyze because of its dependence on external transport phenomena, which were difficult to consider in the models. A set of CTM simulations should be done in the future to assess the O3-VOCs-NOx chemistry.
In this study, the relative contributions of main emission sources to the typical ambient concentrations of key pollutants, such as sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ...and particulate matter (PM10 and PM2.5) in Guayaquil, Ecuador, were investigated. A previous urban emissions inventory for mobile sources was expanded to include other transportation means and main industrial activities using the EMEP/EEA methodology to achieve this objective. The WRF/CALMET/CALPUFF modeling system was used to simulate the annual spatiotemporal distribution of air pollution in the city. According to the model, NO2 concentrations exceed the yearly value and 1-h Ecuadorian standards (40 and 200 μg/m3) in 1 % and 6 % of the cells of the modeling domain, respectively. These hotspots related to local sources were located in the northwest center of the city. The contributions of the manufacturing sector, thermal power plants, ports, airports, and road traffic were assessed individually, and the results indicated that air quality in the study area was strongly dominated by road traffic. The contributions of NO2, CO, PM10, and PM2.5 at the city level reached 76 %, 96 %, 90 %, and 92 % of the annual mean, respectively. In the case of SO2, the manufacturing sector made the most significant contribution (75 %), followed by thermal power plants (16 %). Furthermore, an analysis at 14 specific locations across Guayaquil identified spatial variations that may support the design and development of an air quality monitoring network for the city.
•Emissions estimated for mobile sources, power plants, and industry in Guayaquil.•Road traffic is the most important emission source in the city.•Pollution dispersion modeled with the WRF/CALMET/CALPUFF over 1-yr period.•Road traffic responsible of 92 % of PM2.5 and 76 % of NO2 ambient concentration.•91 % of SO2 concentration attributed to manufacturing sector and power plants.
In recent years, Spain has implemented a number of air quality control measures that are expected to lead to a future reduction in fine particle concentrations and an ensuing positive impact on ...public health.
We aimed to assess the impact on mortality attributable to a reduction in fine particle levels in Spain in 2014 in relation to the estimated level for 2007.
To estimate exposure, we constructed fine particle distribution models for Spain for 2007 (reference scenario) and 2014 (projected scenario) with a spatial resolution of 16×16km2. In a second step, we used the concentration–response functions proposed by cohort studies carried out in Europe (European Study of Cohorts for Air Pollution Effects and Rome longitudinal cohort) and North America (American Cancer Society cohort, Harvard Six Cities study and Canadian national cohort) to calculate the number of attributable annual deaths corresponding to all causes, all non-accidental causes, ischemic heart disease and lung cancer among persons aged over 25 years (2005–2007 mortality rate data). We examined the effect of the Spanish demographic shift in our analysis using 2007 and 2012 population figures.
Our model suggested that there would be a mean overall reduction in fine particle levels of 1µg/m3 by 2014. Taking into account 2007 population data, between 8 and 15 all-cause deaths per 100,000 population could be postponed annually by the expected reduction in fine particle levels. For specific subgroups, estimates varied from 10 to 30 deaths for all non-accidental causes, from 1 to 5 for lung cancer, and from 2 to 6 for ischemic heart disease. The expected burden of preventable mortality would be even higher in the future due to the Spanish population growth. Taking into account the population older than 30 years in 2012, the absolute mortality impact estimate would increase approximately by 18%.
Effective implementation of air quality measures in Spain, in a scenario with a short-term projection, would amount to an appreciable decline in fine particle concentrations, and this, in turn, would lead to notable health-related benefits. Recent European cohort studies strengthen the evidence of an association between long-term exposure to fine particles and health effects, and could enhance the health impact quantification in Europe. Air quality models can contribute to improved assessment of air pollution health impact estimates, particularly in study areas without air pollution monitoring data.
•Effective implementation of air quality policies would decline fine particles levels.•It was estimated a mean overall reduction in fine particles of 1µg/m3 by 2014 in Spain.•A range from 2365 to 4163 all-cause deaths could be postponed annually in Spain.•Air quality control plans would lead to notable health-related benefits.
Nature-based solutions and green urban infrastructures are becoming common measures in local air quality and climate strategies. However, there is a lack of analytical frameworks to anticipate the ...effect of such interventions on urban meteorology and air quality at a city scale. We present a modelling methodology that relies on the weather research and forecasting model (WRF) with the building effect parameterization (BEP) and the community multiscale air quality (CMAQ) model and apply it to assess envisaged plans involving vegetation in the Madrid (Spain) region. The study, developed within the VEGGAP Life project, includes the development of two detailed vegetation scenarios making use of Madrid’s municipality tree inventory (current situation) and future vegetation-related interventions. An annual simulation was performed for both scenarios (considering constant anthropogenic emissions) to identify (i) variations in surface temperature and the reasons for such changes, and (ii) implications on air-quality standards according to EU legislation for the main pollutants (PM10, PM2.5, NO2 and O3). Our results suggest that vegetation may have significant effects on urban meteorology due to changes induced in relevant surface properties such as albedo, roughness length or emissivity. We found a net-heating effect of around +0.18 °C when trees are introduced in dry, scarcely vegetated surfaces in the city outskirts. In turn, this enhances the planetary boundary layer height (PBLH), which brings about reductions in ambient concentrations of relevant pollutants such as NO2 (in the range of 0.5–0.8 µg m−3 for the annual mean, and 2–4 µg m−3 for the 19th highest 1 h value). Conversely, planting new trees in consolidated urban areas causes a cooling effect (up to −0.15 °C as an annual mean) that may slightly increase concentration levels due to less-effective vertical mixing and wind-speed reduction caused by increased roughness. This highlights the need to combine nature-based solutions with emission-reduction measures in Madrid.
This study quantifies the vegetation impact on urban meteorology by means of the numerical model WRF (Weather Research and Forecasting model). The assessment was made for two months: July and ...January. These were considered as representative for the summer and winter seasons, for the reference year 2015 in three European cities: Bologna, Milano, and Madrid. Two simulations at 1 km resolution were conducted over the cities with and without the actual urban vegetation, called VEG and NOVEG, respectively, in the model input. Then, the impact of vegetation was evaluated as the difference between the two simulations (VEG-NOVEG) for temperature, relative humidity, and wind speed fields. In general, we found that, as can be expected, urban vegetation tends to cool the atmosphere, enhance the humidity, and reduce the wind speed. However, in some cases, areas with the opposite behaviour exist, so that no a priori results can be attributed to the presence of urban vegetation. Moreover, even when major impact is confined around grid cells where urban vegetation is present, changes in meteorological quantities can be observed elsewhere in the city’s area. The magnitude of urban vegetation impact is higher in summer than in winter and it depends on the city’s morphological peculiarities, such as urban texture and vegetation types and distribution: average July temperature variations due to the presence of urban vegetation reach peaks of −0.8 °C in Milano, −0.6 °C Madrid, and −0.4 °C in Bologna, while in January, the values range between −0.3 and −0.1 °C. An average heating effect of ca. +0.2 °C is found in some parts of Madrid in January. For relative humidity, we found increments of 2%–3% in July and 0.5%–0.8% in January, while a decrease in wind speed was found between 0.1 and 0.5 m/s, with the highest occurring in Madrid during July.
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