Development of standardized method for the determination of the degradation of nitric oxide (NO) in the air by photocatalytic materials: Inter-laboratory validation tests

International audienceThe need of a uniform experimental procedure for assessing the performance of photocatalytic inorganic materials contained in building materials led the European Committee for Standardization (CEN/TC386/WG2) to elaborate a Technical Specification (TS).Taking into consideration the importance of the effects which will be of possible variations in the implementation of the reference method, parallel photocatalytic tests according to the TS were performed in the current study. 6 European labs were participated in an inter-laboratory exercise where the experiments had to be done in a special design CEN reactor using LED system. The experimental procedure and conditions were taken from the draft TS and were referred to the average irradiance, inlet NO & NO 2 concentration, T o C and RH inside the reactor, flow and reactor net volume. Identical photocatalytic samples were provided to all participants. The results obtained from the 6 labs showed a variation between 18% and 31% on the photocatalytic NO conversion while the mean value was 26%. The corresponding photocatalytic rate was ranged between 2600 μg/m 2 h and 4100 μg/m 2 h presenting a mean value of 3400 μg/m 2 h. The homogeneity of the lamp and the homogeneity of the deposition of TiO 2 are the main factors impacting the results

AIRUSE-LIFE+:A harmonized PM speciation and source apportionment in five southern European cities

The AIRUSE-LIFE+ project aims at characterizing similarities and heterogeneities in particulate matter (PM) sources and contributions in urban areas from southern Europe. Once the main PMx sources are identified, AIRUSE aims at developing and testing the efficiency of specific and non-specific measures to improve urban air quality. This article reports the results of the source apportionment of PM₁₀ and PM_2.5 conducted at three urban background sites (Barcelona, Florence and Milan, BCN-UB, FI-UB and MLN-UB), one suburban background site (Athens, ATH-SUB) and one traffic site (Porto, POR-TR). After collecting 1047 PM₁₀ and 1116 PM_2.5 24 h samples during 12 months (from January 2013 on) simultaneously at the five cities, these were analysed for the contents of OC, EC, anions, cations, major and trace elements and levoglucosan. The USEPA PMF5 receptor model was applied to these data sets in a harmonized way for each city. <br><br> The sum of vehicle exhaust (VEX) and non-exhaust (NEX) contributes between 3.9 and 10.8 µg m⁻³ (16–32 %) to PM₁₀ and 2.3 and 9.4 µg m⁻³ (15–36 %) to PM_2.5, although a fraction of secondary nitrate is also traffic-related but could not be estimated. Important contributions arise from secondary particles (nitrate, sulfate and organics) in PM_2.5 (37–82 %) but also in PM₁₀ (40–71 %), mostly at background sites, revealing the importance of abating gaseous precursors in designing air quality plans. <br><br> Biomass burning (BB) contributions vary widely, from 14–24 % of PM₁₀ in POR-TR, MLN-UB and FI-UB, 7 % in ATH-SUB, to  &lt;  2 % in BCN-UB. In PM_2.5, BB is the second most important source in MLN-UB (21 %) and in POR-TR (18 %), the third one in FI-UB (21 %) and ATH-SUB (11 %), but is again negligible (&lt; 2 %) in BCN-UB. This large variability among cities is mostly due to the degree of penetration of biomass for residential heating. In Barcelona natural gas is very well supplied across the city and is used as fuel in 96 % of homes, while in other cities, PM levels increase on an annual basis by 1–9 µg m⁻³ due to biomass burning influence. Other significant sources are the following. <br><br> &ndash; Local dust, 7–12 % of PM₁₀ at SUB and UB sites and 19 % at the TR site, revealing a contribution from road dust resuspension. In PM_2.5 percentages decrease to 2–7 % at SUB-UB sites and 15 % at the TR site. <br><br> &ndash; Industry, mainly metallurgy, contributing 4–11 % of PM₁₀ (5–12 % in PM_2.5), but only at BCN-UB, POR-TR and MLN-UB. No clear impact of industrial emissions was found in FI-UB and ATH-SUB. <br><br> &ndash; Natural contributions from sea salt (13 % of PM₁₀ in POR-TR, but only 2–7 % in the other cities) and Saharan dust (14 % in ATH-SUB, but less than 4 % in the other cities). <br><br> During high pollution days, the largest sources (i.e. excluding secondary aerosol factors) of PM₁₀ and PM_2.5 are VEX + NEX in BCN-UB (27–22 %) and POR-TR (31–33 %), BB in FI-UB (30–33 %) and MLN-UB (35–26 %) and Saharan dust in ATH-SUB (52–45 %). During those days, there are also quite important industrial contributions in BCN-UB (17–18 %) and local dust in POR-TR (28–20 %)

Effects of PM, TVOCs and comfort parameters on indoor air quality of residences with young children

Indoor air pollution has been implicated in an array of detrimental health effects. Although infants and young children spend most of their day inside their residence, information regarding their exposure to indoor pollutants is still limited. Therefore, the objectives of this study were: a) to characterize the concentrations of particulate matter (PM) and total volatile organic compounds (TVOCs) that young children are exposed to; b) to define comfort parameters for living rooms and children&apos;s bedrooms; c) to identify the determinants of indoor PM and TVOC concentrations; and d) to examine how the socioeconomic status of inhabitants and their daily activities affect diurnal variations in these indoor pollutants. In this context, a study of PM, TVOCs, and comfort parameters was conducted in Athens, Greece, in residences with young children below three years of age. Sampling campaigns were conducted over a 6–7 day period using real time monitoring. The mean indoor PM 1 , PM 2.5 , and PM 10 concentrations were 8.1, 10.6, and 20.9 μg/m 3 , respectively. Mean concentrations of TVOCs ranged between 24 μg/m 3 and 890 μg/m 3 , indicating high variance across the studied dwellings. Carbon dioxide (CO 2 ) levels exceeded the reference value of 1000 ppm in several residences, especially in children&apos;s bedrooms, while air exchange rates (AERs) were found to be lower than 0.5 h −1 in all the studied houses. The results indicated that both PM and TVOC concentrations were mainly related to the activities of the study participants inside their residences. © 2019 Elsevier Lt

Indoor air quality and dustborne biocontaminants in bedrooms of toddlers in Athens, Greece

Contaminants of biological origin, such as fungi and bacteria, are ubiquitous inside the residences and especially in bedroom microenvironments. Epidemiological studies have shown that fungal exposure is associated with respiratory and allergic symptoms. Infants and young children comprise a susceptible population to study, since they spend most of their day inside their rooms. A study was undertaken to investigate environmental factors (temperature and relative humidity), indoor pollutants (PM2.5, CO2), building characteristics and occupant activities in relation to the spectrum and levels of settled fungi in 25 Greek young&apos;s children bedrooms, and to evaluate the fungal qualitative and quantitative composition of houses with and without asthmatic/allergic children. In this context, on-site house inspections to study the Indoor Air Quality (IAQ) in bedrooms of young children below three years of age were conducted in Athens, Greece. Sampling campaigns were conducted over one-week period using Electrostatic Dust Collectors (EDCs) to quantify fungal and bacterial exposure in settled dust and real-time monitoring techniques for environmental parameters (T, RH, CO2, PM2.5). The present investigation revealed that the predominant dustborne genus was Cladosporium followed by Alternaria and Aspergillus, and that living in a suburban area, the presence of an attached garage and the presence of a carpet in the bedroom were significant predictors of fungal concentrations. Furthermore, although the difference was not statistically significant, higher fungal concentrations were recorded in the houses with asthmatic or atopic children. © 2020 Elsevier Lt

Application of Photocatalytic Technology for NOx Removal

Materials that contain a photocatalyst have a semipermanent capacity for removing harmful gases from the ambient air. It is the purpose of this study to investigate the photocatalystic activity of commercial paints containing TiO2 nanoparticles towards NO and NO2. Experiments were carried out in a stainless steel (30m-3) walk-in type environmental chamber (Indoortron), under "real world setting" conditions of temperature, relative humidity, irradiation and pollutant concentrations. Two types of nanoraticleTiO2-containing paints were tested for their depolluting properties: a mineral silicate paint and a water-based styrene acrylic paint. The result showed a significant effect of TiO2-materials in reducing NOx. It was found that up to 74% of NO and 27% of NO2 where photocatalytically degraded by the mineral silicate paint, while degradation percentage using the styrene acrylic paint reached 91% and 71% for NO and NO2, respectively. The photocatalytic rate of NO on the mineral and styrene acrylic paint was calculated to 0.11 mg m-2s and 0.18 mg m-2s, respectively, indicating higher photocatalytic performance of the organic based material. The effect of relative humidity (RH) was also investigated. An increase of RH from 20% to 50% inhibited the NOx photocatalysis in the surface of the samples.JRC.I.5-Physical and chemical exposure

Particulate matter levels in a suburban Mediterranean area: Analysis of a 53-month long experimental campaign

Parallel measurements of ambient particulate matter mass in terms of PM10, PM2.5 and PM2.5-10, conducted during a 53 months long experiment, between 2003 and 2008. The data constituting one of the longest simultaneous comparative data sets for the three PM fractions in Europe, collected at a suburban area of Athens, Aghia Paraskevi. Total means of mass concentrations for PM10, PM2.5 and PM2.5-10 were in the order of 34.8, 18.0 and 23.8μg/m3, respectively. Seasonal variability of PM levels governed by the fact that the specific site is dominated by secondary aerosol emissions with the concentrations presenting a shift to the warm period. During the whole sampling period PM10 were mainly composed of PM2.5 while particles with the bigger diameter proved to be strongly correlated in all the cases. It would be interesting to mention that all the three aerosol fractions did not present any association with the inorganic pollutants. Stagnant conditions as well as the wind direction proved to be key mechanisms for the configuration of the air quality patterns. Saronic Gulf sea-breeze development enhanced the aerosol transportation from the industrialized greater area of Piraeus and the polluted center of the city, to the Northern suburbs. © 2010 Elsevier B.V

The role of meteorology on different sized aerosol fractions (PM 10, PM 2.5, PM 2.5-10)

The scope of the present study is to assess the influence of meteorology on different diameter particles (PM 10, PM 2.5, PM 2.5-10) during a 53months long experimental campaign at an urban Mediterranean area. Except for the investigation of the wind, temperature and relative humidity role, day by day synoptic conditions were classified over the Attica peninsula in order to explore as well, the role of the synoptic scale atmospheric circulation. The strong dependence of the aerosols character on their various sources, not only explain the different diameter particles behavior and their differentiation with the inorganic pollutants but also highlights the need for an effective emission policy. High PM 10 and PM 2.5-10 concentrations found to be closely related to the southwesterly regime, suggesting long range transport from the &apos;polluted&apos; south sector while the general prevalence of the secondary particles generation revealed the health hazard. PM 2.5 showed a weaker correlation than the bigger particles with both the circulation patterns and the parameters&apos; fluctuations. Temporal pollutants variations were clearly governed by the emissions patterns while the low wind speed was not necessarily a good indicator of high concentration levels. Finally it was found that only during the open/close anticyclonic days and the southwesterly wind regime the morning levels were continuously higher than those of the night. © 2012 Elsevier B.V