Annual Mean Concentrations Of NO2 Research Articles

Trends of inorganic sulfur and nitrogen species at an urban site in western Canada (2004–2018)

A 15-year (2004–2018) record of measurement data of gaseous and particulate sulfur and nitrogen pollutants in air collected at an urban site in Burnaby in western Canada was analyzed for generating their decadal trends using three different methods, including linear regression, Mann-Kendall test and Theil-Sen trend estimator (MK-TS), and ensemble empirical mode decomposition (EEMD). Annual mean concentration of SO2 and SO42− decreased by about 59% and 42%, respectively, during the 15-year period. The slower decreases of SO42− than SO2 were mainly caused by the increased O3 concentration and temperature in spring and summer, which promoted conversion of SO2 to SO42− through gas-phase reaction, and by the increased aerosol pH value and availability of H2O2 in winter, which enhanced aqueous-phase SO42− formation. Accordingly, the sulfur oxidation ratio (SOR) increased by 23% or more in spring, summer, and winter during the 15-year period. Annual mean concentrations of NO2 and NO3− declined by 36% and 38%, respectively, during this period. On seasonal basis, NO3− decreased faster than NO2 in autumn and slower in winter. The non-linear responses of NO3− to NO2 concentration decreases were more evident in winter than the other seasons, partly due to the increased particulate NO3− fraction caused by decreased temperature, increased aerosol pH value, and enhanced NO3− formation caused by increased O3 concentrations. Annual mean concentration of NH3 showed small increases due to stable NH3 emission and reduced conversion of NH3 to NH4+. NH4+ concentration decreased by 51% during the 15-year period. These results suggest that reduced oxidants levels are likely responsible for weakened formation of secondary inorganic aerosols, besides emission reductions for SO2 and NO2.

Long-term exposure to nitrogen dioxide air pollution and breast cancer risk: A nested case-control within the French E3N cohort study

Nitrogen dioxide (NO2) is an important air pollutant due to its adverse effects on human health. Yet, current evidence on the association between NO2 and the risk of breast cancer lacks consistency. In this study, we investigated the association between long-term exposure to NO2 and breast cancer risk in the French E3N cohort study. Association of breast cancer risk with NO2 exposure was assessed in a nested case-control study within the French E3N cohort including 5222 breast cancer cases identified over the 1990–2011 follow-up period and 5222 matched controls. Annual mean concentrations of NO2 at participants’ residential addresses for each year from recruitment 1990 through 2011, were estimated using a land use regression (LUR) model. Multivariable conditional logistic regression models were used to compute odds ratios (ORs) and their 95% confidence intervals (CIs). Additional analyses were performed using NO2 concentrations estimated by CHIMERE, a chemistry transport model. Overall, the mean NO2 exposure was associated with an increased risk of breast cancer. In all women, for each interquartile range (IQR) increase in NO2 levels (LUR: 17.8 μg/m3), the OR of the model adjusted for confounders was 1.09 (95% CI: 1.01–1.18). The corresponding OR in the fully adjusted model (additionally adjusted for established breast cancer risk factors) was 1.07 (95% CI: 0.98–1.15). By menopausal status, results for postmenopausal women were comparable to those for all women, while no association was observed among premenopausal women. By hormone receptor status, the OR of estrogen receptor positive breast cancer = 1.07 (95% CI: 0.97–1.19) in the fully adjusted model. Additional analyses using the CHIMERE model showed slight differences in ORs estimates. The results of this study indicate an increased risk of breast cancer associated with long-term exposure to NO2 air pollution. Observing comparable effects of NO2 exposure estimated by two different models, reinforces these findings.

Long-term trends in ambient air pollutants and the effect of meteorological parameters in Tabriz, Iran

Long-term trends (2006–2017) and spatial variations of four ambient gaseous air pollutants (NO2, NO, SO2, and CO) in Tabriz, Iran were analyzed via the nonparametric Mann-Kendall trend test and Moran's I index. The relationships between ambient air pollutants and meteorological parameters were also investigated using Spearman's rank correlation test. The ambient gaseous air pollutants (NO2, NO, and CO), except for SO2, increased during the study period. The annual mean concentrations of NO2, NO, SO2, and CO were 46.3, 41.8, 29.5 μg/m3, and 3.5 mg/m3, respectively. NO2 concentrations were higher than the WHO AQG (40 μg/m3) and National Air Quality Standard (100 μg/m3) in all years. NO2, NO, SO2, and CO concentrations were higher in winter (51.3, 91.0, 40.7 μg/m3 and 4.0 mg/m3) compared to summer (34.0, 26.0, 21.0 μg/m3 and 3.2 mg/m3), presenting a U-shaped monthly pattern. Based on Spearman's rank correlation analysis, all gaseous air pollutants demonstrated a significant correlation with meteorological parameters (e.g., solar radiation and temperature, wind speed, relative humidity, and precipitation) at the confidence level of 95% (p-value < 0.05). Our findings can help improve the understanding of the air pollutants' spatial and temporal patterns in the studied area in a developing country and present valuable implications for Tabriz policy-makers to tackle air pollution and adopt strategies for air pollution reduction in the future. The findings will also aid pollution controllers and authorities to enact policies to further analyze the costs and benefits of air pollution management programs in Tabriz.

From urban neighbourhood environments to cognitive health: a cross-sectional analysis of the role of physical activity and sedentary behaviours

BackgroundThere is a dearth of studies on the effects of the neighbourhood environment on adults’ cognitive function. We examined how interrelated aspects of the built and natural neighbourhood environment, including air pollution, correlate with adults’ cognitive function, and the roles of physical activity and sedentary behaviours in these associations.MethodsWe used data from 4,141 adult urban dwellers who participated in the Australian Diabetes, Obesity and Lifestyle 3 study on socio-demographic characteristics, neighbourhood self-selection, physical activity and sedentary behaviours, and cognitive function. Neighbourhood environmental characteristics included population density, intersection density, non-commercial land use mix, and percentages of commercial land, parkland and blue space, all within 1 km residential buffers. We also calculated annual mean concentrations of NO2 and PM2.5. Generalised additive mixed models informed by directed acyclic graphs were used to estimate the total, direct and indirect effects of environmental attributes on cognitive functions and the joint-significance test was used to examine indirect effects via behaviours.ResultsIn the total effects models, population density and percentage of parkland were positively associated with cognitive function. A positive association of PM2.5 with memory was also observed. All neighbourhood environmental attributes were directly and/or indirectly related to cognitive functions via other environmental attributes and/or physical activity but not sedentary behaviours. Engagement in transportation walking and gardening frequency partially mediated the positive effects of the neighbourhood environment on cognitive function, while frequency of transportation walking mediated the negative effects.ConclusionsIn the context of a low-density country like Australia, denser urban environments with access to parkland may benefit residents’ cognitive health by providing opportunities for participation in a diversity of activities. A more fine-grained characterisation of the neighbourhood environment may be necessary to tease out the negative and positive impacts of inter-related characteristics of urban neighbourhood environments on cognitive function.

Spatial and temporal distribution characteristics of ground-level nitrogen dioxide and ozone across China during 2015–2020

In recent years, the emissions control in nitrogen oxides (NO x ) was conducted across China, but how the concentrations of NO x and its product ozone (O3) in the atmosphere varied in space and time remains uncertain. Here, the spatial and temporal distributions of nitrogen dioxide (NO2) and O3 in 348 cities of China based on the hourly concentrations data during 2015–2020 were investigated, and the relationships among NO2, O3 and meteorological and socioeconomic parameters were explored. It is shown that higher NO2 and O3 concentrations were mainly distributed in North, East and Central China, which are economically developed and densely populated regions. The annual mean concentrations of NO2 increased from 2015 to 2017 but decreased from 2017 to 2020. The annual variations in O3 generally exhibited an upward trend in 2015–2019 but decreased by 5% from 2019 to 2020. About 74% and 78% of cities had a decline in NO2 and O3 in 2020, respectively, compared to 2019, due to the limits of the motorized transports and industrial production activities during COVID-19 lockdown. The monthly mean concentrations of NO2 showed an unusual decrease in February in all regions due to the reduced emissions during the Chinese Spring Festival holidays. Compared to 2019, the mean concentrations of NO2 in January, February and March, 2020 during COVID-19 lockdown decreased by 16%, 28% and 20%, respectively; O3 increased by 13% and 14% in January and February, respectively, but decreased by 2% in March, 2020. NO2 and O3 concentrations are likely associated with anthropogenic and natural emissions. In addition, meteorological parameters can affect NO2 and O3 concentrations by influencing the production process, the diffusion and local accumulation, and the regional circulations.

Land-use, transport and vehicle technology futures: An air pollution assessment of policy combinations for the Cambridge Sub-Region of the UK

This paper reports on an investigation of the impact on air-quality of combinations of urban form development scenarios and vehicle fleet technology changes. The scenarios combine policies affecting urban land-use plans within the Cambridge Sub-Region of the UK, alongside technological changes within the projected vehicle fleet. Broadly, the scenarios consist of the ‘Trend’ for urban form policy and vehicle technology and the urban form policy options of ‘Planned expansion’, ‘Market-led development’ and ‘Urban compaction’, each combined with form-appropriate technological scenarios addressing the uptake of current, and future, technologies in the vehicle fleet. The framework developed for environmental assessment is described, from land-use transport interaction, through traffic assignment and emissions modelling, through to dispersion calculations.The urban form-vehicle technology combinations have been assessed in terms of overall vehicle kilometres travelled (VKT), greenhouse gas (CO2) emissions, and local air quality (NOx, NO2, PM, HC). Results are presented for 2021 and show that overall network emissions change from −13% (Compaction) to +8% (Market-led) relative to the Trend, but effects on emissions in individual districts (NOx) may much greater, −40% to +50%. Annual mean concentrations of NO2 at the street level may vary by −7 to 8 μg/m3. The use of electric vehicles in the ‘Urban compaction’ scenario aids mitigation of air quality issues in the city centre. The results are discussed with respect to the feasibility of scenario implementation, current approaches to planning, and trends in vehicle technology. Limitations of the modelling framework are also identified, and future developments outlined.

Long term measurements of sulfur dioxide, nitrogen dioxide, ammonia, nitric acid and ozone in Africa using passive samplers

Abstract. In this paper we present the long term monitoring of ambient gaseous concentrations within the framework of the IDAF (IGAC-DEBITS-AFRICA) program. This study proposes for the first time an analysis of long-term inorganic gas concentrations (1998 to 2007) of SO2, NO2, HNO3, NH3 and O3, determined using passive samplers at seven remote sites in West and Central Africa. Sites are representative of several African ecosystems and are located along a transect from dry savannas-wet savannas-forests with sites at Banizoumbou (Niger), Katibougou and Agoufou (Mali), Djougou (Benin), Lamto (Cote d'Ivoire), Zoetele (Cameroon) and Bomassa (Congo). The strict control of measurement techniques as well as the validation and inter-comparison studies conducted with the IDAF passive samplers assure the quality and accuracy of the measurements. For each type of African ecosystem, the long term data series have been studied to document the levels of surface gaseous concentrations. The seasonal and interannual variability have also been analyzed as a function of emission source variations. We compared the measured West and Central African gas concentrations to results obtained in other parts of the world. Results show that the annual mean concentrations of NO2, NH3, HNO3 measured in dry savannas are higher than those measured in wet savannas and forests that have quite similar concentrations. Annual mean NO2 concentrations vary from 0.9±0.2 in forests to 2.4±0.4 ppb in the dry savannas, NH3 from 3.9±1.4 to 7.4±0.8 ppb and HNO3 from 0.2±0.1 to 0.5±0.2 ppb. Annual mean O3 and SO2 concentrations are lower for all ecosystems and range from 4.0±0.4 to 14.0±2.8 and from 0.3±0.1 to 1.0±0.2 ppb, respectively. A focus on the processes involved in gas emissions from dry savannas is presented in this work, providing explanations for the high concentrations of all gases measured at the three dry savannas sites. At these sites, seasonal concentrations of all gases are higher in the wet season. Conversely, concentrations are higher in the dry season in the wet savannas. In forested regions, we measure no significant difference between wet and dry seasons. This unique database of long term gases concentrations monitoring is available at: http://medias.obs-mip.fr/idaf/.

Estimating Retrospectively Exposures to Outdoor Air Pollution at the Intraurban Scale in an Ontario Cohort Study

ISEE-0575 Background: We assessed retrospectively intraurban exposures in support of an ongoing cohort study in Ontario of long-term air pollution among 646,000 adults identified from the Canadian T1 family tax file (T1FF) database. Methods: We assessed exposures at addresses of subjects (six-character postal codes) in 1982, as listed on the T1FF file, who lived in Hamilton, Toronto, and Windsor, Ontario using: 1) small-scale concentrations of NO2 in 2002 which were determined from land-use regression models based on dense exposure surveys conducted that year; 2) land use and vehicular traffic (1982 and 2002); and 3) average daily concentrations of NO2 measured at monitoring sites (1982 and 2002). For each city separately, we extrapolated to 1982 the land-use regression maps developed in 2002 as follows: 1) annual mean concentrations from monitoring sites were regressed against spatial characteristics of land use and traffic in 1982 and 2002, respectively; 2) the residuals from the regression models were interpolated using inverse distance weighting; 3) point-by-point concentrations were estimated by adding the interpolated residuals to the linear predictors from these regression models; 4) ratios of estimated annual concentrations between 1982 and 2002 were calculated at every location; and 5) the land use regression map in 2002 was multiplied by these ratios to obtain small-scale concentrations of NO2 in 1982. Results: The annual mean concentrations of NO2 in Hamilton, Toronto, and Windsor decreased between 1982 and 2002 by 30%, 16%, and 30%, respectively. The reductions were not spatially homogenous; in Toronto, for example, the highest decline occurred in the central areas (∼20%) as compared to the periphery of the city (∼5%). Detailed maps will be presented. Conclusion: The ambient concentrations of NO2 decreased over time. There were important spatial variations in the reductions within cities and accounting for this will improve the accuracy of estimates of relative risk.

Joint analysis of air pollution in street canyons in St. Petersburg and Copenhagen

Abstract The bi-annual data set of concentrations of several traffic-related air pollutants, measured continuously in street canyons in St. Petersburg and Copenhagen, is analysed jointly using different statistical techniques. Annual mean concentrations of NO2, NOx and, especially, benzene are found systematically higher in St. Petersburg than in Copenhagen but for ozone the situation is opposite. In both cities probability distribution functions (PDFs) of concentrations and their daily or weekly extrema are fitted with the Weibull and double exponential distributions, respectively. Sample estimates of bi-variate distributions of concentrations, concentration roses, and probabilities of concentration of one pollutant being extreme given that another one reaches its extremum are presented in this paper as well as auto- and co-spectra. It is demonstrated that there is a reasonably high correlation between seasonally averaged concentrations of pollutants in St. Petersburg and Copenhagen.

Long-term ambient air pollution and respiratory symptoms in adults (SAPALDIA study). The SAPALDIA Team.

The association between long-term exposure to ambient air pollution and respiratory symptoms was investigated in a cross-sectional study in random population samples of adults (aged 18 to 60 yr, n = 9,651) at eight study sites in Switzerland. Information on respiratory symptoms was obtained with an extended version of the European Community Respiratory Health Survey questionnaire. The impact of annual mean concentrations of air pollutants was analyzed separately for never-, former, and current smokers. After controlling for age, body mass index, gender, parental asthma, parental atopy, low education, and foreign citizenship, we found positive associations between annual mean concentrations of NO2, total suspended particulates, and particulates of less than 10 micrometers in aerodynamic diameter (PM10) and reported prevalences of chronic phlegm production, chronic cough or phlegm production, breathlessness at rest during the day, breathlessness during the day or at night, and dyspnea on exertion. We found no associations with wheezing without cold, current asthma, chest tightness, or chronic cough. Among never-smokers, the odds ratio (95% confidence interval) for a 10 micrograms/ m3 increase in the annual mean concentration of PM10 was 1. 35 (1.11 to 1.65) for chronic phlegm production, 1.27 (1.08 to 1.50) for chronic cough or phlegm production, 1.48 (1.23 to 1.78) for breathlessness during the day, 1.33 (1.14 to 1.55) for breathlessness during the day or at night, and 1.32 (1.18 to 1.46) for dyspnea on exertion. No associations were found with annual mean concentrations of O3. Similar associations were also found for former and current smokers, except for chronic phlegm production. The observed associations remained stable when further control was applied for environmental tobacco smoke exposure, past and current occupational exposures, atopy, and early childhood respiratory infections when restricting the analysis to long-term residents and to non- alpine areas, and when excluding subjects with physician-diagnosed asthma. The high correlation between the pollutants makes it difficult to sort out the effect of one single pollutant. This study provides further evidence that long-term exposure to air pollution of rather low levels is associated with higher prevalences of respiratory symptoms in adults.