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Abstract: The aim of this study was to evaluate the air quality of an indoor swimming pool, analyzing diurnal and seasonal variations in microbiological counts and chemical parameters. The results indicated that yeast and bacteria counts, as well as carbon dioxide (CO2), nitrogen oxides (NOx) and O3 concentrations, showed significant diurnal difference. On the other hand, temperature, relative humidity (R.H.), yeast counts and concentrations of CO2, particles, O3, toluene, and benzene showed seasonal differences. In addition, the relationship between indoor and outdoor air and the degree of correlation between the different parameters have been calculated, suggesting that CO2, fine particles and NOx would have indoor origin due to the human activity and secondary reactions favored by the chemical and environmental conditions of the swimming pool; while O3, benzene and toluene, would come from outside, mainly. The overall results indicated that indoor air quality (IAQ) in the swimming pool building was deficient by the high levels of CO2 and microorganisms, low temperatures, and high R.H., because frequently the limits established by the legislation were exceeded. This fact could be due to the poor ventilation and the inadequate operation of heating, ventilation, and air‐conditioning systems. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 health crisis has temporarily forced the lockdown of entire countries. This work reports the short-term effects on air quality of such unprecedented paralysis of industry and transport in different continental cities in Spain, one of the countries most affected by the virus and with the hardest confinement measures. The study takes into account sites with different sizes and diverse emission sources, such as traffic, residential or industrial emissions. This work reports new field measurement data for the studied pandemic period and assesses the air quality parameters within the historic trend of each pollutant and site. Thus, 2013–2020 data series from ground-air quality monitoring networks have been analysed to find out statistically significant changes in atmospheric pollutants during March–June 2020 due to this sudden paralysis of activity. The results show substantial concentration drops of primary pollutants, including NO x , CO, BTX, NMHC and NH 3. Particulate matter changes were smaller due to the existence of other natural sources. During the lockdown the ozone patterns were different for each studied location, depending on the VOCs-NOx ratios, with concentration changes close to those expected from the historical series in each site and not statistically attributable to the health crisis effects. Finally, the gradual de-escalation and progressive increase of traffic density within cities reflects a slow recovery of primary pollutants. The results and conclusions for these cities, with different sizes and population, and specific emission sources, may serve as a behavioural model for other continental sites and help understand future crises. Image 1 • SARS-CoV-2 lockdown and de-escalation's effects on air quality in different size cities in Spain. • Significant and fast reduction of NOx, CO, BTXs, NMHC and NH3 have been observed. • Lower changes in PM were found during the crisis and not clear trends for O3. • Pollutant levels remained below pre-lockdown values despite gradual de-escalation. [ABSTRACT FROM AUTHOR]

The formation of secondary organic aerosol (SOA) generated by irradiating styrene in the presence and/or absence of OH, NOx, H 2 O vapour and seed aerosol has been investigated for the first time. Experiments were conducted in a smog chamber at 298 K and atmospheric pressure. Styrene decay was measured by gas chromatography with a mass spectrometric detector (GC-MS), and the temporal evolution of the aerosol was monitored using a fast mobility particle sizer (FMPS). The SOA yield increases as the initial styrene concentration increases, leading to yields ranging from 1.8% to 3.5% for styrene photolysis, and from 2.4% to 5.0% for its photooxidation. In both cases, the organic aerosol formation can be expressed by a one-product gas/particle partitioning absorption model. The particle number concentration, mass and yield decrease in the presence of NOx and seed aerosol but increase at higher relative humidity (RH). The gas phase and SOA composition were analysed offline using a filter/denuder sampling system simultaneously collecting gas- and particle-phase products. Benzaldehyde was confirmed as the main gas-phase product of the reaction. However, although products in the particle phase were detected, they could not be identified. Moreover, the aqueous filter extracts were analysed using UV-Visible spectrophotometry to determine differences in the optical properties of SOA produced in the presence and absence of NOx. The results from this work may be used to discuss the implications of atmospheric SOA generation from styrene degradation., (Copyright © 2019 Elsevier Ltd. All rights reserved.)