Absolute rate coefficient measurements have been carried out for the Cl atom reaction with a series of esters, at room temperature (298 ± 2 K) and in the pressure range 15−60 Torr, using the laser photolysis−resonance fluorescence technique. The rate coefficients obtained (in units of cm3 molecule-1 s-1) are as follows:  methyl formate (1.83 ± 0.21) × 10-12, ethyl formate (1.34 ± 0.15) × 10-11, n-propyl formate (5.63 ± 0.65) × 10-11, n-butyl formate (1.41 ± 0.17) × 10-10, methyl acetate (2.85 ± 0.35) × 10-12, ethyl acetate (2.01 ± 0.25) × 10-11, n-propyl acetate (7.76 ± 0.92) × 10-11, n-butyl acetate (1.74 ± 0.20) × 10-10, isopropyl acetate (2.68 ± 0.34) × 10-11, isobutyl acetate (1.08 ± 0.13) × 10-10, tert-butyl acetate (2.42 ± 0.28) × 10-11, sec-butyl acetate (9.1 ± 1.0) × 10-11, methyl propionate (1.98 ± 0.26) × 10-11, methyl butyrate (8.6 ± 0.9) × 10-11, methyl valerate (1.7 ± 0.2) × 10-10, and methyl caproate (2.72 ± 0.32) × 10-10. The results are discussed in terms of structure−reactivity relationship.

The reactions of Cl with a series of linear alcohols: methanol (k1), ethanol (k2), 1-propanol (k3), 1-butanol (k4), and 1-pentanol (k5) were investigated as a function of temperature in the range of 264-382 K by laser photolysis-resonance fluorescence. The obtained kinetic data were used to derive the following Arrhenius expressions: k1=(3.55+/-0.22)x10(-10) exp[-(559+/-40)T], k2=(5.25+/-0.52)x10(-11) exp[(190+/-68)T], k3=(2.63+/-0.21)x10(-11) exp[(525+/-51)T], k4=(3.12+/-0.31)x10(-11) exp[(548+/-65)T], and k5=(3.97+/-0.48)x10(-11) exp[(533+/-77)T] (in units of cm(3) molecule(-1) s(-1)). To our knowledge, these are the first absolute kinetic data reported for 1-butanol and 1-pentanol and also the first kinetic study as a function of temperature for these two compounds. Results, mechanism, and tropospheric implications are discussed and compared with the reported reactivity with OH radicals. Moreover, a theoretical insight into the mechanisms of these reactions has also been pursued through ab initio Möller-Plesset second-order perturbation treatment calculations with 6-311G** basis sets. Optimized geometries and vibrational frequencies have been obtained for transition states and molecular complexes appearing along the different reaction pathways. Furthermore, molecular energies have been calculated at quadratic configuration interaction with single, double, and triple excitations level in order to get an estimation of the activation energies.

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Public health authorities have been paramount in guaranteeing that adequate fresh air ventilation is promoted in classrooms to avoid SARS-CoV-2 transmission in educational environments. In this work it was aimed to assess ventilation conditions (carbon dioxide, CO 2 ) and suspended particulate matter (PM 2.5 , PM 10 and UFP) levels in 19 classrooms – including preschool, primary and secondary education – located in the metropolitan area of Ciudad Real, Central-Southern Spain, during the school’ reopening (from September 30th until October 27th, 2020) after about 7 months of lockdown due to COVID-19 pandemic. The classrooms that presented the worst indoor environmental conditions, according to the highest peak of concentration obtained, were particularly explored to identify the possible influencing factors and respective opportunities for improvement. Briefly, findings suggested that although ventilation promoted through opening windows and doors according to official recommendations is guaranteeing adequate ventilation conditions in most of the studied classrooms, thus minimizing the risk of SARS-CoV-2 airborne transmission, a total of 5 (26%) surveyed classrooms were found to exceed the recommended CO 2 concentration limit value (700 ppm). In general, preschool rooms were the educational environments that registered better ventilation conditions, while secondary classrooms exhibited the highest peak and average CO 2 concentrations. In turn, for PM 2.5 , PM 10 and UFP, the concentrations assessed in preschools were, on average about 2-fold greater than the levels obtained in both primary and secondary classrooms. In fact, the indoor PM 2.5 and PM 10 concentrations substantially exceeded the recommended limits of 8hr-exposure, established by WHO, in 63% and 32% of the surveyed classrooms, respectively. Overall, it is expected that the findings presented in this study will assist the establishment of evidence-based measures (mainly based on ensuring proper ventilation rates and air filtration) to mitigate preventable environmental harm in public school buildings, mainly at local and national levels.

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Smog chamber/GC techniques were used to investigate the atmospheric degradation of two unsaturated alcohols, 1-penten-3-ol and (Z)-2-penten-1-ol, by oxidation with chlorine atoms at atmospheric pressure of N(2) or air, as a function of temperature. The rate coefficients at 298 K were (units in cm(3) molecule(-1) s(-1)): (2.35 ± 0.31) × 10(-10) and (3.00 ± 0.49) × 10(-10) for 1-penten-3-ol and (Z)-2-penten-1-ol, respectively. The identified and quantified gas-phase products (with molar yields in brackets) were carbonyl compounds such as chloroacetaldehyde (33 ± 1%), propionaldehyde (39 ± 1%), acetaldehyde (8 ± 3%) and 1-penten-3-one (2%) from 1-penten-3-ol; and chlorobutyraldehyde (19 ± 1%), propionaldehyde (27 ± 1%), acetaldehyde (18 ± 2%) and (Z)-2-pentenal (36 ± 1%) from (Z)-2-penten-1-ol. A parallel theoretical study at the QCISD(T)6-311G**//MP2/6-311G** level was carried out to facilitate understanding of the reaction mechanism. Both the theoretical and experimental studies indicated that addition of Cl to the double bond of the unsaturated alcohol is the dominant reaction pathway, although the H-abstraction channel cannot be excluded. The atmospheric lifetimes of those unsaturated alcohols were calculated and the results are discussed.

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