Molecular mechanism for rapid autoxidation in alpha-pinene ozonolysis

Aerosol affects Earth's climate and the health of its inhabitants. A major contributor to aerosol formation is the oxidation of volatile organic compounds. Monoterpenes are an important class of volatile organic compounds, and recent research demonstrate that they can be converted to low-volatility aerosol precursors on sub-second timescales following a single oxidant attack. The alpha -pinene + O-3 system is particularly efficient in this regard. However, the actual mechanism behind this conversion is not understood. The key challenge is the steric strain created by the cyclobutyl ring in the oxidation products. This strain hinders subsequent unimolecular hydrogen-shift reactions essential for lowering volatility. Using quantum chemical calculations and targeted experiments, we show that the excess energy from the initial ozonolysis reaction can lead to novel oxidation intermediates without steric strain, allowing the rapid formation of products with up to 8 oxygen atoms. This is likely a key route for atmospheric organic aerosol formation. Oxidation of volatile organic compounds leads to aerosol formation in the atmosphere, but the mechanism of some fast reactions is still unclear. The authors, using quantum chemical modelling and experiments, reveal that in key monoterpenes the cyclobutyl ring that would hinder the reactivity is broken in the early exothermic steps of the reaction.Peer reviewe

Direct Measurements of Covalently Bonded Sulfuric Anhydrides from Gas-Phase Reactions of SO₃ with Acids under Ambient Conditions

Sulfur trioxide (SO3) is an important oxide of sulfur and a key intermediate in the formation of sulfuric acid (H2SO4, SA) in the Earth’s atmosphere. This conversion to SA occurs rapidly due to the reaction of SO3 with a water dimer. However, gas-phase SO3 has been measured directly at concentrations that are comparable to that of SA under polluted mega-city conditions, indicating gaps in our current understanding of the sources and fates of SO3. Its reaction with atmospheric acids could be one such fate that can have significant implications for atmospheric chemistry. In the present investigation, laboratory experiments were conducted in a flow reactor to generate a range of previously uncharacterized condensable sulfur-containing reaction products by reacting SO3 with a set of atmospherically relevant inorganic and organic acids at room temperature and atmospheric pressure. Specifically, key inorganic acids known to be responsible for most ambient new particle formation events, iodic acid (HIO3, IA) and SA, are observed to react promptly with SO3 to form iodic sulfuric anhydride (IO3SO3H, ISA) and disulfuric acid (H2S2O7, DSA). Carboxylic sulfuric anhydrides (CSAs) were observed to form by the reaction of SO3 with C2 and C3 monocarboxylic (acetic and propanoic acid) and dicarboxylic (oxalic and malonic acid)-carboxylic acids. The formed products were detected by a nitrate-ion-based chemical ionization atmospheric pressure interface time-of-flight mass spectrometer (NO3--CI-APi-TOF; NO3--CIMS). Quantum chemical methods were used to compute the relevant SO3 reaction rate coefficients, probe the reaction mechanisms, and model the ionization chemistry inherent in the detection of the products by NO3--CIMS. Additionally, we use NO3--CIMS ambient data to report that significant concentrations of SO3 and its acid anhydride reaction products are present under polluted, marine and polar, and volcanic plume conditions. Considering that these regions are rich in the acid precursors studied here, the reported reactions need to be accounted for in the modeling of atmospheric new particle formation.</p

Road Traffic Emissions Lead to Much Enhanced New Particle Formation through Increased Growth Rates

New particle formation (NPF) is a major source of atmospheric aerosol particles, including cloud condensation nuclei (CCN), by number globally. Previous research has highlighted that NPF is less frequent but more intense at roadsides compared to urban background. Here, we closely examine NPF at both background and roadside sites in urban Central Europe. We show that the concentration of oxygenated organic molecules (OOMs) is greater at the roadside, and the condensation of OOMs along with sulfuric acid onto new particles is sufficient to explain the growth at both sites. We identify a hitherto unreported traffic-related OOM source contributing 29% and 16% to total OOMs at the roadside and background, respectively. Critically, this hitherto undiscovered OOM source is an essential component of urban NPF. Without their contribution to growth rates and the subsequent enhancements to particle survival, the number of &gt;50 nm particles produced by NPF would be reduced by a factor of 21 at the roadside site. Reductions to hydrocarbon emissions from road traffic may thereby reduce particle numbers and CCN counts.</p

Global burden of cardiovascular diseases and risk factors, 1990–2019: update from the GBD 2019 study

Cardiovascular diseases (CVDs), principally ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and a major contributor to disability. This paper reviews the magnitude of total CVD burden, including 13 underlying causes of cardiovascular death and 9 related risk factors, using estimates from the Global Burden of Disease (GBD) Study 2019. GBD, an ongoing multinational collaboration to provide comparable and consistent estimates of population health over time, used all available population-level data sources on incidence, prevalence, case fatality, mortality, and health risks to produce estimates for 204 countries and territories from 1990 to 2019. Prevalent cases of total CVD nearly doubled from 271 million (95% uncertainty interval [UI]: 257 to 285 million) in 1990 to 523 million (95% UI: 497 to 550 million) in 2019, and the number of CVD deaths steadily increased from 12.1 million (95% UI:11.4 to 12.6 million) in 1990, reaching 18.6 million (95% UI: 17.1 to 19.7 million) in 2019. The global trends for disability-adjusted life years (DALYs) and years of life lost also increased significantly, and years lived with disability doubled from 17.7 million (95% UI: 12.9 to 22.5 million) to 34.4 million (95% UI:24.9 to 43.6 million) over that period. The total number of DALYs due to IHD has risen steadily since 1990, reaching 182 million (95% UI: 170 to 194 million) DALYs, 9.14 million (95% UI: 8.40 to 9.74 million) deaths in the year 2019, and 197 million (95% UI: 178 to 220 million) prevalent cases of IHD in 2019. The total number of DALYs due to stroke has risen steadily since 1990, reaching 143 million (95% UI: 133 to 153 million) DALYs, 6.55 million (95% UI: 6.00 to 7.02 million) deaths in the year 2019, and 101 million (95% UI: 93.2 to 111 million) prevalent cases of stroke in 2019. Cardiovascular diseases remain the leading cause of disease burden in the world. CVD burden continues its decades-long rise for almost all countries outside high-income countries, and alarmingly, the age-standardized rate of CVD has begun to rise in some locations where it was previously declining in high-income countries. There is an urgent need to focus on implementing existing cost-effective policies and interventions if the world is to meet the targets for Sustainable Development Goal 3 and achieve a 30% reduction in premature mortality due to noncommunicable diseases

Global Burden of Cardiovascular Diseases and Risk Factors, 1990–2019: Update From the GBD 2019 Study

Cardiovascular diseases (CVDs), principally ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and a major contributor to disability. This paper reviews the magnitude of total CVD burden, including 13 underlying causes of cardiovascular death and 9 related risk factors, using estimates from the Global Burden of Disease (GBD) Study 2019. GBD, an ongoing multinational collaboration to provide comparable and consistent estimates of population health over time, used all available population-level data sources on incidence, prevalence, case fatality, mortality, and health risks to produce estimates for 204 countries and territories from 1990 to 2019. Prevalent cases of total CVD nearly doubled from 271 million (95% uncertainty interval [UI]: 257 to 285 million) in 1990 to 523 million (95% UI: 497 to 550 million) in 2019, and the number of CVD deaths steadily increased from 12.1 million (95% UI:11.4 to 12.6 million) in 1990, reaching 18.6 million (95% UI: 17.1 to 19.7 million) in 2019. The global trends for disability-adjusted life years (DALYs) and years of life lost also increased significantly, and years lived with disability doubled from 17.7 million (95% UI: 12.9 to 22.5 million) to 34.4 million (95% UI:24.9 to 43.6 million) over that period. The total number of DALYs due to IHD has risen steadily since 1990, reaching 182 million (95% UI: 170 to 194 million) DALYs, 9.14 million (95% UI: 8.40 to 9.74 million) deaths in the year 2019, and 197 million (95% UI: 178 to 220 million) prevalent cases of IHD in 2019. The total number of DALYs due to stroke has risen steadily since 1990, reaching 143 million (95% UI: 133 to 153 million) DALYs, 6.55 million (95% UI: 6.00 to 7.02 million) deaths in the year 2019, and 101 million (95% UI: 93.2 to 111 million) prevalent cases of stroke in 2019. Cardiovascular diseases remain the leading cause of disease burden in the world. CVD burden continues its decades-long rise for almost all countries outside high-income countries, and alarmingly, the age-standardized rate of CVD has begun to rise in some locations where it was previously declining in high-income countries. There is an urgent need to focus on implementing existing cost-effective policies and interventions if the world is to meet the targets for Sustainable Development Goal 3 and achieve a 30% reduction in premature mortality due to noncommunicable diseases

Use of cryogenic trap and liquid chromatography-triple quadrupole mass spectrometry for indoor air analysis

Monitoring of indoor air quality (IAQ) is important because IAQ is directly related to human health and comforts. The purpose of this study was to develop a non-targeted approach for the screening of organic compounds present in indoor air. The sampling was done using cryogenic active and passive samplers, and the separation and analysis were done by using a liquid chromatograph coupled with a triple quadrupole mass spectrometer (LC-QQQ-MS). First, experimental design for sampling by variables, cooling temperature and sampling period was made and optimized to -15 ˚C and 120 minutes respectively to ensure efficient sample collection. For mass spectrometry in both positive and negative ionization modes, the ion source parameters, gas temperature, gas flow, nebulizer pressure and capillary voltage were optimized to 300 ˚C, 10 L/min, 45 psi and 4000 V respectively to enable as much detector response as possible facilitating detection and analysis of the compounds in the sample. The concentration of compounds in the raw sample being very low, one important step was to optimize the sample preparation method to enrich the sample for smooth detection and further analysis. Since the sample was collected in the form of condensate water, different sample preparation methods such as evaporation, liquid-liquid extraction (LLE) and solid-phase extractions (SPEs) with different cartridges were adopted for preconcentration. Comparing the outcomes from different sample preparation methods, it was found that sequential SPE using C2 and C18 cartridges gives maximum compound recovery, e.g., 1.5 and 2.6 times compared to evaporation and LLE respectively in positive ion mode, and 2.6 and 4.1 times in negative ion mode. Therefore, this methodology was adopted to analyze the condensate water samples from two sick houses in Finland. The results from the sick houses were compared with a reference house having no sick building syndrome (SBS) to look for potential compounds causing health issues. The data analysis was done using MZmine 2.3.4 software. Additionally, tandem mass spectrometric (MS/MS) acquisition parameters were optimized and product ions were determined as the initial step of identification of compounds in the sample of the first house. The methods developed in this work would be useful to analyze various natural samples including the analysis of outdoor air also

A systematic study on the kinetics of H-shift reactions in pristine acyl peroxy radicals

A series of acyl peroxy radical H-shifts were systematically studied using computational approaches. Acyl peroxy radicals were categorized into small- (ethanal-pentanal), medium- (hexanal and heptanal) and large-sized (octanal and nonanal) molecules. The H-shifts spanning from 1,4 to 1,9 were inspected for each studied system. For all acyl peroxy radicals, it is the combination of barrier heights and quantum mechanical tunneling that explains the yield of the peracid alkyl radical product. We used the ROHF-ROCCSD(T)-F12a/VDZ-F12//omega B97X-D/aug-cc-pVTZ level of theory to estimate the barrier heights and the subsequent rate coefficients with the exception of the smallest acyl peroxy radical ethanal, for which MN15 density functional was applied. The estimated multiconformer H-shift rate coefficients were found to be in the range of 10-2 s-1 to 10-1 s-1 for the fastest H-migrations. The determined rates imply that these H-shift reactions are often competitive with other RO2 loss processes and should be considered as a path to functionalization in modelling not only rural but also urban air quality.A systematic study is carried out for the first time on H-shifts in pristine acyl peroxy radicals. The fastest rates were found to be in the range of 10-2 to 10-1 s-1, remaining competitive even under moderately polluted atmospheric conditions.Peer reviewe

A systematic study on the kinetics of H-shift reactions in pristine acyl peroxy radicals

A series of acyl peroxy radical H-shifts were systematically studied using computational approaches. Acyl peroxy radicals were categorized into small- (ethanal-pentanal), medium- (hexanal and heptanal) and large-sized (octanal and nonanal) molecules. The H-shifts spanning from 1,4 to 1,9 were inspected for each studied system. For all acyl peroxy radicals, it is the combination of barrier heights and quantum mechanical tunneling that explains the yield of the peracid alkyl radical product. We used the ROHF-ROCCSD(T)-F12a/VDZ-F12//ωB97X-D/aug-cc-pVTZ level of theory to estimate the barrier heights and the subsequent rate coefficients with the exception of the smallest acyl peroxy radical ethanal, for which MN15 density functional was applied. The estimated multiconformer H-shift rate coefficients were found to be in the range of 10−2 s−1 to 10−1 s−1 for the fastest H-migrations. The determined rates imply that these H-shift reactions are often competitive with other RO2 loss processes and should be considered as a path to functionalization in modelling not only rural but also urban air quality.Peer reviewe

Baseline prevalence of high blood pressure and its predictors in a rural adult population of Bangladesh: Outcome from the application of WHO PEN interventions

Abstract This cross‐sectional study estimated the prevalence of high blood pressure (BP) and examined its predictors at baseline following protocol 1 (actions 1 and 2) of World Health Organization (WHO) Package of Essential Noncommunicable Disease (PEN) Interventions in a selected rural area of Bangladesh. A total of 11 145 adults (both sex and age ≥ 18 years) completed both the questionnaire and clinical measurements at the household and community clinics, respectively. We defined high BP as systolic BP ≥ 120 mmHg or diastolic BP ≥ 80 mmHg, prehypertension (pre‐HTN) as systolic BP 120–139 mmHg or diastolic BP 80–89 mmHg, and hypertension (HTN) as systolic BP ≥ 140 mmHg or diastolic BP ≥ 90 mmHg and/or anti‐hypertensive drug intake for the raised BP. The prevalence of high BP was 51.2% (pre‐HTN, 25.3%; HTN, 25.9%). Among them, the proportion of pre‐HTN was higher among men (28.7%) while HTN was higher among women (27.4%). Other than fast food intake (pre‐HTN, OR: 1.110, P = .063) and women sex (HTN, OR: 1.236, P < .001), the pre‐HTN and HTN had higher odds for having same predictors as follows: age ≥ 40 years, family history of HTN, physical inactivity, central obesity, generalized obesity, and diabetes. In conclusion, the application of WHO PEN protocol 1 detected one‐fourth of the rural adult population had pre‐HTN and HTN respectively, and the common significant predictors of those were the age, family history of HTN, physical inactivity, generalized obesity, and diabetes

Baseline prevalence of hyperglycemia and its predictors among community clinic users of a selected rural area of Bangladesh: A cross‐sectional study using the WHO PEN Protocol 1

Abstract Aims/Introduction Our objective was to estimate the prevalence of hyperglycemia at baseline, and identify its predictors among community clinic (CC) users from a selected rural area of Bangladesh. Materials and Methods This cross‐sectional study partly used the baseline data of implementation research in which a total of 11,244 adults visited the CC, and their blood glucose, blood pressure and anthropometry were evaluated according to ‘Action 2’ of the World Health Organization (WHO) Package of Essential Noncommunicable Disease Interventions (PEN) protocol 1. Of these, 11,144 had complete information on demography, chronic diseases and their risk factors, which were collected during the implementation of ‘Action 1’ of WHO PEN protocol 1 at the household level. Hyperglycemia, prediabetes (PreD) and type 2 diabetes were diagnosed using the WHO criteria. Results Using WHO PEN protocol 1, the estimated baseline prevalence was 12.5% for hyperglycemia, 3.4% for PreD and 9.2% for type 2 diabetes, and was more prevalent among men compared with women. PreD and type 2 diabetes had significantly higher odds ratio (OR >1) of having common risk factors as follows: age ≥40 years (PreD, P < 0.001; type 2 diabetes, P < 0.001), generalized obesity (PreD, P < 0.001; type 2 diabetes, P = 0.005) and hypertension (PreD, P < 0.000; type 2 diabetes, P < 0.001). Furthermore, participants with a family history of diabetes appeared to be a significant predictor of type 2 diabetes (P < 0.001), but not for PreD (P = 0.303). Conclusions Hyperglycemia, preD and type 2 diabetes showed a comparatively high prevalence among the CC users of the selected rural area. Obesity and hypertension are the key modifiable risk factors that should be reduced using a CC‐centered risk reduction strategy