Smog warning systems are components of adaptation strategies that are adopted by governments around the world to protect their citizens from extreme episodes of air pollution. As part of a growing ...research stream on the effectiveness of these systems, this article presents the results of a study on the impacts of an automated phone warning and advising system for individuals vulnerable to air pollution. A sample of 1328 individuals were recruited and randomly assigned to treatment and control groups. The treatment group received smog warning while the control group did not. Data were collected via three phone surveys, two before and one after issuing the smog warning. The comparison between treatment and control groups indicates that exposure to a smog warning improved information on the occurrence of smog episodes (
= 484, OR = 5.58,
= 0.00), and knowledge on protective behaviors. Furthermore, members of treatment group were more likely to avoid exposure to smog episodes by spending more time inside with the windows closed than usual (
= 474, OR = 2.03,
= 0.00). Members of treatment group who take medication in the form of aerosol pumps also kept these devices on themselves more frequently than those of control group (
= 109, OR = 2.15,
= 0.03). The system however had no discernible effects on the awareness of air pollution risks, reduction of health symptoms related to smog and the use of health system services. The absence of health benefits could be related to the lower actual exposure to air pollution of such vulnerable groups during winter.
Kinetic studies of the reaction of ethyl glycolate HOCH2C(O)OCH2CH3 with OH radicals (kOH) and Cl atoms (kCl) have been conducted by the relative method using a glass atmospheric reactor by “in situ” ...Fourier Transform Infrared (FTIR) and Gas Chromatography equipped with flame ionization detection by Solid Phase Micro Extraction (GC-FID/SPME) at room temperature and atmospheric pressure. The following relative rate coefficients were determined using several reference compounds and two different techniques: kEG + OH-FTIR = (4.36 ± 1.21) × 10−12; kEG + OH-GC-FID= (3.90 ± 0.74) × 10−12; and kEG + Cl-GC-FID= (6.40 ± 0.72) × 10−11 all values in units of cm3.molecule−1.s−1. Complementary product studies were performed under comparable conditions to the kinetic tests, in order to identify the reaction products and to postulate their tropospheric oxidation mechanisms. The reaction of OH radicals and Cl atoms with ethyl glycolate initiates via H-atom abstraction from alkyl groups of the molecule. Formic acid was positively identified as a reaction product by FTIR. On the other hand, formaldehyde, acetaldehyde, glycolic acid; and formic acid were identified by the GC-MS technique. The Structure–Activity Relationship, (SAR) calculations were also implemented to estimate the more favorable reaction pathways and compare them with the products identified. Tropospheric lifetimes of τOH = 34 h and τCl = 5.5 days were estimated to determine how these investigated reactions might affect the air quality. In this sense, average ozone production of O3 = 0.75 and a Photochemical Ozone Creation Potential, POCP, of 38 were calculated for the hydroxyl ester studied.
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•First kinetic and product study of ethyl glycolate + OH and Cl radicals.•Reactivity decreases with substitution from OH to H and C(O) to C(O)O.•Two aldehydes and two acids were identified as reaction products.•Tropospheric resident times of few hours with a local impact.•Moderate Ozone Photochemical Potential Creation of 38.
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The BiVO4/Cu2O/rGO (3.0 wt%) heterojunction was successfully synthesized. The response of ternary heterojunction to 1 ppm NO2 is 8 times higher than the pure BiVO4 and 5 times higher ...than the p-n heterojunction of BiVO4/Cu2O, and the response time is low which is only 51.3 s near room temperature (60 °C). The enhancing reason benefits from the formation of BiVO4/Cu2O p-n heterojunction and the addition of rGO.
•The BiVO4/Cu2O/rGO(3.0 wt%) composite was successfully fabricated by facile method.•The novel composite based sensor exhibits enhancing sensing performance to NO2.•The enhancement benefits from interface regulation caused by p-n heterojunction.•The work has reference action for designing and fabricating rGO/semiconductor sensors.
NO2 is a toxic gas that can cause photochemical smog, acid rain and ozone layer depletion. The reduced graphene oxide (rGO) decorated nanocomposites of semiconductor metal oxides (MOS) as sensing materials of NO2 sensors have received much attention. Here, BiVO4/Cu2O/rGO nanocomposite was successfully prepared by a facile solvothermal method and thermal reduction method. The gas-sensing test indicates that the response of optimum nanocomposite to 1 ppm NO2 is 8 times higher than the pure BiVO4 and 5 times higher than the p-n heterojunction of BiVO4/Cu2O, respectively at 60 °C operating temperature. The response time and recovery time also shortened compared to pure BiVO4 and BiVO4/Cu2O composite, and this composite has better stability for detection of NO2, which benefits from the superimposed effect of p-n heterojunction formation and rGO decoration. This work can provide reference for improving the sensing properties of metal oxide semiconductor composites for detection of NO2.
Abstract
Severe events of wintertime particulate air pollution in Beijing (winter haze) are associated with high relative humidity (RH) and fast production of particulate sulfate from the oxidation ...of sulfur dioxide (SO
2
) emitted by coal combustion. There has been considerable debate regarding the mechanism for SO
2
oxidation. Here we show evidence from field observations of a haze event that rapid oxidation of SO
2
by nitrogen dioxide (NO
2
) and nitrous acid (HONO) takes place, the latter producing nitrous oxide (N
2
O). Sulfate shifts to larger particle sizes during the event, indicative of fog/cloud processing. Fog and cloud readily form under winter haze conditions, leading to high liquid water contents with high pH (>5.5) from elevated ammonia. Such conditions enable fast aqueous-phase oxidation of SO
2
by NO
2
, producing HONO which can in turn oxidize SO
2
to yield N
2
O.This mechanism could provide an explanation for sulfate formation under some winter haze conditions.
TiO2 is a widely used material in building coatings. Many studies have revealed that TiO2 promotes the heterogeneous oxidation of SO2 and the subsequent sulfate formation. However, whether and how ...much TiO2 contributes to the gaseous H2SO4 and subsequent new particle formation (NPF) still remains unclear. Herein, we used a 1 m3 quartz smog chamber to investigate NPF in the presence of TiO2. The experimental results indicated that TiO2 could greatly promote NPF. The increases in particle formation rate (J) and growth rate due to the presence of TiO2 were quantified, and the promotion effect was attributed to the production of gaseous H2SO4. The promotion effect of TiO2 on SO2 oxidation and subsequent NPF decreased gradually due to the formation of surface sulfate but did not disappear completely, instead partly recovering after washing with water. Moreover, the promotion effect of TiO2 on NPF was observed regardless of differences in RH, and the most significant promotion effect of TiO2 associated with the strongest NPF occurred at an RH of 20%. Based on the experimental evidence, the environmental impact of TiO2 on gaseous H2SO4 and particle pollution in urban areas was estimated.
Extremely high levels of atmospheric sulfate aerosols have still frequently occurred in China especially in winter haze periods and often been underestimated by models due to some missing formation ...mechanisms. Here we investigated the heterogeneous reaction dynamics of SO2 oxidation by the abundantly co-existing O3 and NO2 in the urban atmosphere of China by using a laboratory smog chamber simulation technique. Our results showed that with an increase of NH3 concentrations from 0.05 ppm to 1.5 ppm, SO2 oxidation by O3 can be greatly promoted and lead to an exponential increase of diameter growth factor (GF) of particles in the chamber from 1.29 to 1.98 for NaCl seeds and from 1.20 to 1.60 for (NH4)2SO4 seeds, along with an increasing uptake coefficient (γ) of SO2 from 4.47 × 10−5 to 1.52 × 10−4 on NaCl seeds and from 2.32 × 10−5 to 5.74 × 10−5 on (NH4)2SO4 seeds, respectively. The heterogeneous production of sulfate from oxidation of SO2 under NH3-rich conditions by O3 and NO2 mixture in the chamber was 2.0–3.5 times the sum of sulfate from SO2 oxidations by O3 and NO2, suggesting a strongly synergetic effect of the mixed oxidants on the heterogeneous oxidation of SO2, which can cause rapid formation of (NH4)2SO4 and NH4NO3 and is responsible for the explosive growth of PM2.5 in the winter haze period of China. Our chamber results further showed that such synergetic process is only efficient under NH3-rich conditions, clearly indicating that the combined controls on O3, NOx and NH3 are necessary for further mitigating the PM2.5 pollution in China.
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•Neutralization by NH3 is the controlling factor for the efficient heterogeneous formation of sulfate.•O3 and NO2 mixture shows a strong synergetic effect on the heterogeneous oxidation of SO2 only under NH3-rich conditions.•The sharply rising ALWC caused by nitrate is responsible for the synergetic effect of mixed oxidants on sulfate formation.
The problem of poor air quality in urban areas has a negative impact on the health of residents. This is especially important during periods of smog. In Poland, as in other countries, the problem of ...poor air quality, especially during the winter season, is associated with a high concentration of particulate pollutants in ambient air (PMsub.10, PMsub.2.5). Sources of particulate emissions, in addition to solid-fuel boilers, include means of transportation, especially those equipped with diesel engines. In turn, during periods of strong sunshine (spring and summer), the problem of photochemical smog, whose precursors are nitrogen oxides NOsub.X, arises in urban areas. Their main sources of emissions are internal combustion engines. Therefore, to improve air quality in urban areas, changes are being made in the transport sector, among which is upgrading the fleet of urban transport vehicles to low- or zero-emission vehicles, which are more environmentally friendly. In addition, measures that reduce the harmfulness of the transportation sector to air quality include the introduction of clean transportation zones, as well as park-and-ride (P&R) systems. The purpose of this article is to present the results in terms of PMsub.10, PMsub.2.5, and NOx emission reductions, implemented over a period of two years (2021–2022) in the area of the Rzeszow agglomeration, related to the modernization of the suburban bus fleet and the implementation of a P&R system for passenger cars. The results of the study were compared with the value of estimated emissions from coal-fired boilers used for residential heating and hot water, which also contribute to smog. Thanks to the implementation of the project, i.e., the replacement of 52 old buses with new buses of the Euro VI emission class and the construction of new P&R spaces, the total average annual reduction in emissions amounted to approximately 703.6 kg of PMsub.10, approximately 692.7 kg of PMsub.2.5, and a reduction of approximately 10.4 tons of NOsub.X.
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