The intensification of the human activity in urban areas as a result of the increasing population has contributed to the air pollution worsening in cities. To reverse this trend, the European Commission established a legal framework to improve the air quality. Thereby the Member States need to develop air quality plans (AQP) for zones and agglomerations where air quality limit values are exceeded, in order to implement pollution control strategies and meet the legal requirements. Understanding the reasons for the levels of air quality non–compliance as well as evaluating available and commonly used tools to predict the air quality and their effects, is crucial for the decision–making process on air quality management policies. Based on a compilation of regional and local AQP, a review of assessment capabilities and used modeling tools to evaluate the effects of emission abatement measures on the air quality and health was performed. In most cases, models are applied to estimate emissions and to assess the resulting air quality from both reference and emission abatement scenarios. Air quality’s impacts on the health and environment are rarely quantified. Regarding the air quality assessment, beyond the modeling, monitored data for validation of simulations are also used. Some studies, however, do not include the use of air quality models, considering the monitoring network as spatially representative of the study domain (e.g. Lisbon Region, Riga, Malta). In order to overcome methodological limitations for quantifying the impacts of emission abatement measures, economic evaluation techniques or even Integrated Assessment Methodologies (IAM) have been developed. IAM, already applied in some AQP or case studies, namely for Antwerp and London, are used for assessing how reductions in emissions contribute to improve air quality, reduce exposure and protect human health.

The Badboot (Dutch for swimming pool boat) is a floating swimming pool located in the city center of Antwerp in Belgium. The overall design consists of a recycled ferry boat that serves as a restaurant and next to that a newly built ship that harbours an Olympic size swimming pool, sun decks, locker rooms with showers, and a party space. A major design goal of the project was to make the ship as environmentally friendly as possible. To avoid discharge of contaminated waste water in the Antwerp docks, the ship includes onsite treatment of wastewater in a compact constructed wetland. The treatment wetland system was designed to treat wastewater from visitor locker rooms, showers, toilets, two bars, and the wastewater from the restaurant kitchen. Due to the limited space on board the ship, only 188 m² could be allocated to a wetland treatment system. As a result, part of the design included intensification of the wetland treatment process through the use of Forced Bed Aeration, which injects small quantities of air in a very uniform grid pattern throughout the wetland with a mechanical air compressor. The system was monitored between August 2012 and March 2013 (with additional sampling in the autumn of 2014). Flows and loads to the wetland were highly variable, but removal efficiency was extremely high; 99.5 % for chemical oxygen demand (COD), 88.6 % for total nitrogen and 97.2 % for ammonia. The treatment performance was assessed using a first-order, tanks-in-series model (the P-k-C* model) and found to be roughly equivalent to similar intensified wetlands operating in Germany. However, treatment performance was substantially better than data reported on passive wetlands, likely as a result of intensification. Even with mechanically assisted aeration, the total oxygen delivered to the treatment wetlands was insufficient to support conventional nitrification and denitrification, so it is likely that alternate nitrogen removal pathways, such as anammox, are operating in the wetland.

This paper studies the effects of the implementation of wastewater treatment (WWT) on the water quality of small urban river systems by considering as an extreme case study (volumetric contribution of wastewaters >50 %) the evolution of the Zenne River waters (Belgium) over the last 40 years. In urban rivers, organic matter (OM), oxygen, and nutrients are primarily controlled by wastewater releases which depend on the population and the WWT capacity in the river basin, the latter being dependent on environmental policy decisions. We introduce a novel basin-scale evaluation method that considers the evolution of annual pollutant loads at the outlet of the river basin directly as a function of WWT capacity. Based on this approach, we could prove that the load reductions observed after the implementation of WWT in the river basin was a good indicator of the global treatment efficiency of the WWT plants. We also show that high self-purification processes within the river basin may lead to reach minimum levels of OM before the completion of WWT. In addition, the effects of wet weather conditions did also change as a function of the WWT capacity going from positive effects at low capacity to negative effects at high capacity. Finally, the full implementation of WWT in urban river basins does not necessarily guarantee a good status for water quality, mostly because of the high volumetric proportion of treated wastewaters, which do not have the quality standards of river waters.

Within the Flemish Environment and Health studies (FLEHS I, 2002–2006, and FLEHS II, 2007–2012), pesticide exposure, hormone levels and degree of sexual maturation were measured in 14–15-year-old adolescents residing in Flanders (Belgium). In FLEHS II, geometric mean concentrations (with 95 % confidence interval (CI)) of 307 (277–341) and 36.5 ng L⁻¹ (34.0–39.2) were found for p,p′-dichlorophenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB). These values were respectively 26 and 60 % lower than levels in FLEHS I, 5 years earlier. Metabolites of organophosphorus pesticides (OPPs) and of para-dichlorobenzene were measured for the first time in FLEHS II, yielding concentrations of 11.4, 3.27 and 1.57 μg L⁻¹ for the sum of dimethyl- and diethyl phosphate metabolites and 2,5-dichlorophenol (2,5-DCP), respectively. Data on internal exposure of HCB showed a positive correlation with sexual maturation, testosterone and the aromatase index for boys and with free thyroxine (fT4) and thyroid stimulating hormone (TSH) (both boys and girls). For both p,p′-DDE and HCB, a negative association with sexual development in girls was found. The OPP metabolites were negatively associated with sex hormone levels in the blood of boys and with sexual maturation (both boys and girls). The pesticide metabolite 2,5-DCP was negatively correlated with free T4, while a positive association with TSH was reported (boys and girls). These results show that even exposure to relatively low concentrations of pesticides can have significant influences on hormone levels and the degree of sexual maturation in 14–15-year-old adolescents.

In recent years, it has been demonstrated that sewage-based epidemiology can deliver interesting information on trends in illicit drug consumption. However, until now, no real evidence exists that the measured concentrations of drugs in sewage can be exactly correlated with the amounts of drugs used by a specific population. This study aimed therefore at correlating detailed monthly prescription figures of 11 pharmaceuticals (atenolol, bisoprolol, citalopram, fluoxetine, venlafaxine, losartan, telmisartan, valsartan, carbamazepine, metformin, and tramadol) with measured concentrations of these compounds in influent sewage from five sewage treatment plants in Belgium. For 7 out of the 11 substances, a ratio between loads calculated from the prescription figures and loads calculated from measured concentrations in the range of 0.30–3.00 was observed. For four pharmaceuticals (atenolol, bisoprolol, telmisartan, and venlafaxine), the observed relationship was less pronounced. The manuscript gives an overview of the possible uncertainties that are related with the calculated correlations. This study highlights the need for gathering all the necessary information regarding sewage sampling, stability of substances in sewage, pharmacokinetics, and analytical method performance when sewage-based epidemiology studies are performed.