High Concentrations Of Air Pollutants Research Articles

Survey of Lung Function and Respiratory Symptoms Among Online Motorcycle Taxi Drivers in Bekasi City

Background: Online motorcycle taxi drivers have been heavily exposed to high concentration of hazardous air pollutants. This study aimed to describe the lung function and respiratory symptoms among online motorcycle taxi drivers and risk factors which influence them. 
 Methods: The study design was survey research design with sample number of 99 online motorcycle taxi drivers in Bekasi City. Lung function examination was done using spirometer (Spirolab) and the predicted value of lung function was using Pneumobile Project Indonesia. Risk factors and respiratory symptoms were collected using questionnaire. 
 Results: There were 10.1% of subjects with restrictive lung function and 5.1% with obstructive impairment. There were significant association between age of the drivers with restrictive disorders (P=0.006) and the mean difference of %FEV1 (P=0.039). There was a significant relationship between sex (P=0.001) and age (P=0.001) with the mean percent of forced vital capacity (%FVC). The respiratory symptoms collected were cough (17.2%) and shortness of breath (6.1%). There were no significant relationship between respiratory symptoms and lung function. 
 Conclusions: Online motorcycle taxi drivers had respiratory symptoms and lung function impairment, however the causal relationship with the workplace environment is still unclear. Moreover, education about the importance of using personal protective equipment is needed to protect respiratory systems from harmful substances. (J Respir Indo 2019; 39(1): 54-9)

Risk of Polycystic Ovary Syndrome in Women Exposed to Fine Air Pollutants and Acidic Gases: A Nationwide Cohort Analysis.

Background: Air pollutants cause endocrine disorders and hormone disruption. The relationship between air pollutants and polycystic ovary syndrome (PCOS) must be carefully investigated using a nationwide cohort. Methods: Data were extracted from two nationwide databases, namely Longitudinal Health Insurance Database and Taiwan Air Quality Monitoring Database, and analyzed. The study considered a range of data that began on 1 January 2000 and ended on 31 December 2013. Women diagnosed with PCOS were excluded. From the residential data, the study assessed the daily concentrations of sulfur dioxide (SO2), nitrogen oxides (NOx), nitrogen monoxide (NO), nitrogen dioxide (NO2), and PM2.5 the women were exposed to. A Cox proportional hazard regression model was applied to assess PCOS risk. Results: In total, 91,803 women were enrolled in this study; of those women, 2072 developed PCOS after 12 years of follow-up. The mean daily concentrations of SO2, NOx, NO, NO2, and PM2.5 women were exposed to were 4.25 (±1.44) ppb, 20.41 (±6.65) ppb, 9.25 (±4.36) ppb, 20.99 (±3.33) ppb, and 30.85 (±6.16) μg/m3, respectively. Compared with the first-quartile levels of exposure, the fourth-quartile levels of exposure to SO2, NOx, NO, NO2, and PM2.5 increased PCOS risk by 10.31 times (95% CI = 8.35–12.7), 3.37 times (95% CI = 2.86–3.96), 4.18 times (95% CI = 3.57–4.89), 7.46 times (95% CI = 6.38–8.71), and 3.56 times (95% CI = 3.05–4.15), respectively. Conclusion: Women exposed to a high concentrations of air pollutants, namely SO2, NO, NO2, NOx, and PM2.5, had a high PCOS risk.

Mixing Layer Height Retrievals From MiniMPL Measurements in the Chiang Mai Valley: Implications for Particulate Matter Pollution

Urbanized mountain valleys are usually prone to episodes of high concentrations of air pollutants due to the strong interplay between mountain meteorology and synoptic weather conditions. The mountain valley of Chiang Mai is engulfed by air pollutants with particulate matter (PM) concentration remaining above 50 µg m-3 (PM2.5, 24-hour average) during approximately 13 % days every year (mostly during February to April). This study presents the first time continuous measurements of mini- micro pulse LiDAR (MiniMPL) installed on the valley floor of Chiang Mai, providing vertical backscatter profile of aerosols and clouds from April 2017 onwards. This paper analyzes unique dataset of mixing layer (ML) height measurements made during April 2017 to June 2018 with a temporal resolution of 15 minutes. The ML height derived from the backscatter profile measurements are analyzed to understand the annual, monthly and diurnal variations. The ML height depicts distinct diurnal variations for all months of the year, evolving up to < 3.0 km during April to September. From October onwards the ML evolution is gradually inhibited, reducing to < 2.0 km during October to December and < 1.5 km during January to March. The variations in the concentration of PM were found to be partly modulated by the ML variations (Pearson coefficient ≈ −0.50) during dry season (February, March and April), possibly triggering the aerosol-boundary layer feedback mechanism for high concentrations (100 µg m-3) of PM and low ventilation in the valley. The inhibition of ML evolution due to feedback mechanism further escalates the high concentrations of PM, resulting in severe haze conditions on many days during the dry season.

Particle exposure and inhaled dose while commuting in Lisbon

While commuting, individuals are exposed to high concentrations of urban air pollutants that can lead to adverse health effects. This study aims to assess commuters’ exposure to particulate matter (PM) when travelling by car, bicycle, metro and bus in Lisbon. Mass concentrations of PM2.5 and PM10 were higher in the metro. On the other hand, the highest BC and PN0.01-1 average concentrations were found in car and bus mode, respectively. In cars, the outdoor concentrations and the type of ventilation appeared to affect the indoor concentrations. In fact, the use of ventilation led to a decrease of PM2.5 and PM10 concentrations and to an increase of BC concentrations. The highest inhaled doses were mostly observed in bicycle journeys, due to the longest travel periods combined with enhanced physical activity and, consequently, highest inhalation rates.

Ecological load on the industrial area of Irkutsk region

Unfavorable ecological situation has arisen in the Irkutsk region. The Irkutsk region ranks third into the amount of pollutants emitted into air from stationary and mobile sources in the Siberian Federal District in 2017. The enterprise activities results in the emission of harmful substances into atmosphere. High concentration of air pollutants is observed in large cities of the Irkutsk region. The work is aimed at the calculation of the ecological load on the main industrial cities of the Irkutsk region for the period from 2008 to 2017. The relevance of the research issue is determined by the increasing intensity of anthropogenic impact and pollution of the urban environment by emissions from motor vehicles and industrial enterprises. We used data on emissions into the air in cities of the Irkutsk region, presented in the State reports as a source of information. In eight industrial cities of the region, the level of air pollution is assessed as high and very high. The cities of Bratsk and Irkutsk have been included over the years in the Priority List of Russian Cities with the highest air pollution index. All of these industrial cities of region have been experiencing a high anthropogenic load, resulted in heavy air pollution.

Cooking/Window Opening and Associated Increases of Indoor PM2.5 and NO2 Concentrations of Children’s Houses in Kaohsiung, Taiwan

High concentrations of air pollutants and increased morbidity and mortality rates are found in industrial areas, especially for the susceptible group, children; however, most studies use atmospheric dispersion modeling to estimate household air pollutants. Therefore, the aim of this study was to assess the indoor air quality, e.g., CO, CO2, NO2, SO2, O3, particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5), and their influence factors in children’s homes in an industrial city. Children in the “general school”, “traffic school”, and “industrial school” were randomly and proportionally selected. Air pollutants were sampled for 24 h in the living rooms and on the balcony of their houses and questionnaires of time–microenvironment–activity-diary were recorded. The indoor CO concentration of the traffic area was significantly higher than that of the industrial area and the general area. In regard to the effects of window opening, household NO2 and PM2.5 concentrations during window opening periods were significantly higher than of the reference periods. For the influence of cooking, indoor CO2, NO2, and PM2.5 levels during the cooking periods were significantly higher than that of the reference periods. The indoor air quality of children in industrial cities were affected by residential areas and household activities.

RESPIRATORY SYMPTOMS AND LUNG FUNCTION AMONG ONLINE MOTORCYCLE TAXI DRIVERS

SESSION TITLE: Population-Wide Lung Health: Exposures and Risks SESSION TYPE: Original Investigations PRESENTED ON: 10/23/2019 10:45 AM - 11:45 AM PURPOSE: Online motorcycle taxi drivers have been heavily exposed to high concentration of hazardous air pollutants. It will cause harmful effects especially on the respiratory system. This study aimed to describe the respiratory symptoms and lung function among online motorcycle taxi drivers and risk factors that influence them. METHODS: A survey research design of 99 online motorcycle taxi drivers in Bekasi City was done. Lung function was measured using spirometer and predicted volume value from Pneumobile Project Indonesia. Risk factors and respiratory symptoms were collected using questionnaire. RESULTS: This study showed that 10,1% of subjects had restrictive lung function impairment and 5,1% had obstructive lung function impairment. Age had significant association with restrictive disorders (p= 0,006). The mean predicted forced vital capacity (FVC) was 3451 ml and the mean forced expiratory volume in one second (FEV1) was 2959 ml. There was a significant relationship between sex (p=0,001) and age (p=0,001) with the mean percent predicted forced vital capacity (%FVC). Age had significant association with the mean of percent predicted forced expiratory volume in one second (%FEV1) (p=0,039). However there were no significant relationship founded between sex, body mass index, safety equipment, history of smoking, duration of work, asthma history and previous tuberculosis disease with obstructive and restrictive lung function impairment. A proportion of respiratory symptoms among online motorcycle taxi drivers were cough (17,2%) and shortness of breath (6,1%). There were no significant relationship founded between respiratory symptoms and lung function result. CONCLUSIONS: This survey showed online motorcycle taxi drivers have respiratory symptoms and lung function impairment, however the causal relationship with the workplace environment is still unclear. Therefore, it will need further study to explore this findings. Moreover, education to the online motorcycle taxi drivers about the importance of using personal protective equipment will help them to protect respiratory systems from harmful gases. CLINICAL IMPLICATIONS: We report for the first time survey of online motorcycle taxi drivers in Indonesia which showed respiratory and impairment of lung function. Causal relationship with the workplace environment will be better explore with cohort study. Therefore, mask as personal protective equipment should be used in daily basis to protect them from air pollutants. DISCLOSURES: No relevant relationships by Triya Damayanti, source=Web Response No relevant relationships by Jaka Pradipta, source=Web Response no disclosure on file for Agus Susanto

A Low-Cost Passive Monitor for Black Carbon Air Pollution

TPS 651: Air pollution exposure modeling 1, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Background: Developing-country households using solid fuels often have high concentrations of black carbon air pollution. Monitoring, especially in rural areas, is expensive, uncertain, and logistically challenging, and often reflects short-term (~hours or ~day) rather than long-term (~months or longer) conditions. We developed a low-cost (<$10) passive sampler for long-term average black carbon concentration. Method: We tested samplers for multiple months in 20 indoor locations in rural India to determine reproducibility and limits of detection. All locations received duplicate samplers (i.e., two per location). Our approach measures the change over time in sampler filter surface reflectance (pixel intensity [PI]) relative to baseline and to an unexposed reference. Results: Our study is ongoing: to date (March 2019), samplers have been exposed for ~2 months. All samplers (n=40) experienced a measurable change in reflectance (>1.0% relative to reference); none of the samplers have fully saturated yet. Duplicate samplers’ measurements were highly correlated (r>0.99), suggesting excellent reproducibility. Variability in reflectance among locations suggests strong ability to differentiate between higher versus lower long-term average black carbon concentration: specifically, differences between duplicate samplers averaged 1.1% (range: 0.02% to 2.9%) [720 PI (range: 12 to 1900)], whereas the difference among locations was 73% (range: 1.1% to 74%; mean: 18%) [48,000 PI (range: 730 to 49,000; mean: 12,000)]. Conclusions: Results thus far for 20 locations suggest robust reproducibility and precision. For indoor locations investigated, in a community that uses solid fuels, the minimum time-scale for sampling (which reflects the lower limit of detection) appears to be <2 months; the maximum time-scale for sampling (which reflects the upper limit of measurement) appears to be >2 months. Ongoing work will continue investigating reproducibility and limits of detection.

Effects of Environmental Pollution on Changes in Blood Biochemical Parameters

&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; Abstract &#x0D; &#x0D; A metabolic marker in the blood of individuals exposed to air pollution is plausible as some environmental pollutants have been observed to enter the blood stream directly from lungs. The main objective of the current review is to find out changes in biochemical parameters of human blood as a result of environmental pollution. Spatio temporal models involving measurement of Air Quality Index were accommodating to find out the results of development of an aggregate air quality index. Results depicted that mean values of RBC and hemoglobin concentration in blood of exposed children were significantly different from those of non-exposed group. Air pollution may adversely affect children's erythrocytes, particularly PM10 have a significant negative relationship with hemoglobin and RBC numbers while a positive significant relationship with WBC and platelet count. Higher concentrations of air pollutants exposed to pregnant women significantly higher the incidence of pregnancy anemia’s. A strong dose-response relationship was confirmed for both contaminants. It is difficult to establish a causal relationship between specific environmental exposures and complicated multifactorial health outcomes, the application of non-targeted metabolite profiling to assess the effect of air pollution on blood metabolite. Therefore in the present study the main emphasis has been made on the effects of various polluted environment contaminants, their biochemical effects on the composition of blood and various associated disease.&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D;

Assessment of Indoor and Ambient Air Pollution at Complex Buildings in Hanoi

The most typical air pollutants including PM10, CO, SO2, NOx are monitored at different sites indoor (basement, shopping malls) and outdoor (ambient air) of several complex buildings which are used for different purposes of resident, office, and shopping malls in Hanoi. The results show that the indoor air pollution concentrations tend to be higher than the corresponding pollutants of the ambient air. The results show the highest concentrations are in RC building for the same category of floor comparing to the other two buildings. Pollutant concentrations at basement for parking is the highest with the values of PM10, SO2, NOx, CO of 67.1 ± 21.2 µg/m3, 224.8 ± 34.9 µg/m3, 287.3 ± 136.3 µg/m3, 22,372.5 ± 2,324.5 µg/m3, respectively. The high concentration of indoor air pollutants are harmful for human health, especially for those who have longer exposure time.&#x0D; &#x0D; &#x0D; &#x0D;

Acute exposure to urban air pollution impairs olfactory learning and memory in honeybees.

While the ecological effects of pesticides have been well studied in honeybees, it is unclear to what extent other anthropogenic contaminants such as air pollution may also negatively affect bee cognition and behaviour. To answer this question, we assessed the impacts of acute exposure to four ecologically relevant concentrations of a common urban air pollutant-diesel generated air pollution on honeybee odour learning and memory using a conditioned proboscis extension response assay. The proportion of bees that successfully learnt odours following direct air pollution exposure was significantly lower in bees exposed to low, medium and high air pollutant concentrations, than in bees exposed to current ambient levels. Furthermore, short- and long-term odour memory was significantly impaired in bees exposed to low medium and high air pollutant concentrations than in bees exposed to current ambient levels. These results demonstrate a clear and direct cognitive cost of air pollution. Given learning and memory play significant roles in foraging, we suggest air pollution will have increasing negative impacts on the ecosystem services bees provide and may add to the current threats such as pesticides, mites and disease affecting colony fitness.

Comparison of filtration performance of commercially available automotive cabin air filters against various airborne pollutants

Controlling air pollutants in the automobile cabin environment has become increasingly important owing to the health risks of exposure to high concentrations of harmful air pollutants. To protect daily commuters and drivers against the harmful effects of air pollution, modern automobiles are commonly equipped with automotive cabin air filters (ACAFs). Thus, understanding the filtration performance of ACAFs is essential for assessing cabin indoor air quality. In this study, six original equipment manufacturer (OEM) and nine after-market ACAFs were selected and their particulate matter (PM) filtration performance against standard particle (ISO 12103-1 A2 dust), filter pressure drop under various airflow velocities, and gas removal performance against standard test gases (n-butane and toluene) were estimated. In the PM filtration test, the lowest filtration performance occurred at a particle size range of 0.3–0.5 μm, with a filtration efficiency of 50–90%, and the filtration performance increased with increasing particle size. The PM filtration performance of OEM ACAFs (72.3 ± 13.81%) was higher than that of after-market ACAFs (56.4 ± 23.72%). All test OEM ACAFs satisfied the Korea Air Cleaning Association standard filtration performance guidelines for 0.3–0.5-μm particles (>50%), but four of the nine after-market ACAFs did not satisfy the standard guidelines. In addition, only one of the six OEM ACAFs simultaneously satisfied the standard removal performance guidelines for n-butane (>70% after 1 min and >45% after 5 min) and toluene (>80% after 1 min and >70% after 5 min). This study provides valuable baseline information on ACAFs for understanding and improving cabin indoor air quality.

Assessment of common plant parameters as biomarkers of air pollution.

Air pollution is a very serious current environmental issue of human society. Large parts of countries, especially the densely populated cities, having high vehicular movement, industries, and factories, are worst affected. Biomarkers are changes in plant parameters that help in easy assessment of the environmental quality of an area at a certain time. Plants can react to different environmental stresses with the most evident responses shown by the leaves. In the present work, we have studied changes in biochemical parameters in the leaves of a mango plant (Mangifera indica), a very common plant in West Bengal, India, which were collected from four different locations in the city of Kolkata which has a high concentration of air pollutants and one control area from a rural region having a low concentration of air pollutants. It was observed that leaves which were exposed to high amounts of harmful air pollutants showed higher accumulation of molecules such as phenol, proline, malondialdehyde, and cellulose with lower amounts of chlorophyll. From this, we can observe that common environmental stress such as air pollution leads to a change in the synthesis of bioactive molecules to resist the effect of stress on the plant. Thus, from these data, it can be concluded that biochemical parameters can serve as efficient biomarkers of the air quality of an area.

Joint effect of heatwaves and air quality on emergency department attendances for vulnerable population in Perth, Western Australia, 2006 to 2015

BackgroundAs global warming and the frequency and intensity of heatwaves increases, health service utilization, including emergency department attendances (EDA) have correspondingly increased across the world. The impact of air quality on health adds to the complexity of the effects. Potential joint effects between heatwaves and air quality on EDA have been rarely reported in the literature, prompting this study. ObjectivesTo investigate the potential joint effect of heatwaves and air quality on the EDA for vulnerable populations in the Perth metropolitan area, Western Australia. MethodsA time series design was used. Daily data on EDA, heatwaves (excess heat factor>0) and air pollutants (CO, SO2, NO2, O3, PM10 and PM2.5) were collected for Perth, Western Australia from 2006 to 2015. Poisson regression modelling was used to assess the associations between heatwaves, air quality, and EDA. Risk assessments on age, gender, Aboriginality, socio-economic status (SES), and joint effect between heatwaves and air quality on EDA were conducted. ResultsThe EDA rate was higher in heatwave days (77.86/100,000/day) compared with non-heatwave days (73.90/100,000/day) with rate ratio of 1.053 (95% confidence interval 1.048, 1.058). The EDA rate was higher in males, people older than 60 years or younger than 15 years, Aboriginal people, and people with low SES. Exposure to CO, SO2, O3 and PM2.5 increased risk on EDA and exposure to PM2.5 showed joint effect with heatwave and increased risk of EDA by 6.6% after adjustment of all other risk factors. ConclusionsEDA is an important indicator to evaluate heatwave related morbidity for emergency medical service as EDA rate increased during heatwaves with relative high concentrations of air pollutants. As all air pollutants measured in the study were lower than the Australian National Standards, the joint effect of heatwaves and air quality needs to be further examined when it exceeds the standards.

Ambient air pollution and adverse birth outcomes: a systematic review and meta-analysis.

Several reviews have assessed the relationship between exposure to ambient air pollution and adverse birth outcomes during pregnancy, but the results remain controversial. The objective of this study was to assess this correlation quantitatively and to explore sources of heterogeneity. We included all published case-control or cohort studies that evaluated the correlation between ambient air pollution and low birth weight (LBW), preterm birth (PTB), and small for gestational age (SGA). Analytical methods and inclusion criteria were provided on the PROSPERO website (CRD42018085816). We evaluated pooled effects and heterogeneity. Subgroup analyses (grouped by exposure period, study settings, study design, exposure types, data source, Newcastle-Ottawa quality score (NOS), and adjustment for smoking or meteorological factors) were also conducted and publication bias was examined. The risk of bias in systematic reviews (ROBIS) tool was used to evaluate the overall risk of bias in this review. Forty studies met the inclusion criteria. We observed pooled odds ratios (ORs) of 1.03-1.21 for LBW and 0.97-1.06 for PTB when mothers were exposed to CO, NO2, NOx, O3, PM2.5, PM10, or SO2 throughout their pregnancy. For SGA, the pooled estimate was 1.02 in relation to NO2 concentrations. Subgroup analysis and sensitivity analysis decreased the heterogeneity to some extent, such as the subgroups of continuous measures (OR=0.98 (0.97-0.99), I2=0.0%) and NOS>7 (OR=0.98 (0.97-0.99), I2=0.0%) in evaluating the association between PTB and NO2. This review was completed with a low risk of bias. High concentrations of air pollution were significantly related to the higher risk of adverse birth outcomes. However, the sources of heterogeneity among studies should be further explored.

High resolution annual average air pollution concentration maps for the Netherlands

Long-term exposure to air pollution is considered a major public health concern and has been related to overall mortality and various diseases such as respiratory and cardiovascular disease. Due to the spatial variability of air pollution concentrations, assessment of individual exposure to air pollution requires spatial datasets at high resolution. Combining detailed air pollution maps with personal mobility and activity patterns allows for an improved exposure assessment. We present high-resolution datasets for the Netherlands providing average ambient air pollution concentration values for the year 2009 for NO2, NOx, PM2.5, PM2.5absorbance and PM10. The raster datasets on 5×5 m grid cover the entire Netherlands and were calculated using the land use regression models originating from the European Study of Cohorts for Air Pollution Effects (ESCAPE) project. Additional datasets with nationwide and regional measurements were used to evaluate the generated concentration maps. The presented datasets allow for spatial aggregations on different scales, nationwide individual exposure assessment, and the integration of activity patterns in the exposure estimation of individuals.

The "cancer-cold" hypothesis and possible extensions for the Nordic populations.

Cancer incidence is inexplicably high in cold countries. This has been revealed by recent genetic and epidemiological studies. These studies used data from the GLOBOCAN-2012 database, for 186 populations and for a variety of cancer types. Cancer incidence in Nordic people is particularly high for the frequent cancer forms, like breast, prostate and colon cancer. A relationship of cancer with cold is suspected since Inuit and Alaska Indians that live in even more extreme low temperatures have the higher cancer rates in the world. In this article, possible reasons for this phenomenon are discussed. These explanations are related with: evolutionary adaptation to extreme cold, the genetic background of Nordic people, the experimentally proven fast growth and metastasis of tumors at low temperatures, high concentration of certain air pollutants at cold environments, low levels of serum Vitamin D, overdiagnosis by the medical doctors and high quality of the health system in Nordic countries. Lifestyle parameters are not discussed in detail, although these may be equally crucial for cancer risk in cold countries. In conclusion, more studies are needed to elucidate the real causes of this epidemiological pattern.

Characterization and health risks of criteria air pollutants in Delhi, 2017

Severe air pollution events were observed frequently in north India in recent years especially at its capital, Delhi. Criteria air pollutants data at 10 sites for 2017 in Delhi were analyzed. The results show annual fine particulate matter (PM2.5) concentrations exceeded the National Ambient Air Quality Standards (NAAQS) of 60 μg/m3 at all sites from 105.51 (site 10) to 143.23 μg/m3 (site 7). Sub-urban sites (site 8, 9 and 10) had lower PM2.5 concentrations than urban sites. Coarse PM (PM10) and ozone (O3) were also important with annual averages of 399.56 μg/m3 and 75.69 ppb, respectively. Peak PM2.5 occurred at the Diwali in early November and Christmas. Only PM10 showed a significant weekly difference with a weekdays/weekends ratio of ∼1.5. PM2.5/PM10 ratio in episode days with PM2.5 of >60 μg/m3 was higher than non-episode days. Pearson correlation coefficients show O3 was negatively related with CO, SO2, and NO2, while PM2.5 was positively related to these pollutants. Analysis of two extreme events from Nov. 6th to Nov. 14th and Dec. 18th to Dec. 26th shows that meteorological conditions with low wind speed and warm temperature kept PM2.5 concentrations at a high level during these events. Backward trajectory and cluster analysis show the wind coming from northwest of Delhi, where massive anthropogenic emissions were generated, led to high concentrations of air pollutants to Delhi. Health risk analysis reveals that PM2.5 and PM10 were the two major pollutants threatening public health among the six criteria pollutants.

The impact of urbanization on air stagnation: Shenzhen as case study

One of the most concerning consequences arising from the dramatic urbanization in cities is air stagnation and the related high concentration of air pollutants. Many studies have investigated the impact of urbanization on air stagnation, but few have systematically evaluated such impact and its spatial-temporal variances at the municipal scale. This study proposed an approach based on high-resolution urban climate simulations for evaluating the impact of urbanization on air stagnation. We took the city of Shenzhen in south-eastern China, a city that grew from a small fishing and farming village to a highly urbanized city in the past thirty years, as a compelling case study. Using the WRF/Noah LSM/SLUCM model, we simulated and evaluated the probability of 6-hourly air stagnation cases (ASCs) in 1979 and 2010 at the spatial resolution of 1-km2 to demonstrate the change over a thirty-year period. Comparison results show that urbanization worsened the problem of air stagnation in Shenzhen. The number of 6-hourly ASCs has increased by 21,700 for the entire Shenzhen, and by 11.4 on average for each grid with a 1 km2 size. A maximum increase of 458 ASCs in a grid was also observed.

Synoptic Weather Patterns and Associated Air Pollution in Taiwan

ABSTRACT In this study, cluster analysis is applied to the daily averaged wind fields and sea-level pressure observed at surface weather stations in Taiwan from January 2013 to March 2018 to classify the synoptic weather patterns and study the characteristics of corresponding air pollutants, including fine particulate matter (PM2.5), coarse particulate matter (PM10), and ozone (O3). The classification identified six weather types: Clusters 1, 2, and 3 (C1–C3), which are typical winter weather types and associated with high air pollutant concentrations—C3, in particular, influenced by weak synoptic weather, is associated with the lowest wind speeds and the highest PM2.5 and PM10 concentrations and represents the most prevalent weather type that is prone to the occurrence of PM2.5 events; C4, which occurs mostly during seasonal transition months and is associated with the highest O3 concentrations; and C5 and C6, which are summer weather types with low air pollutant concentrations. Further analysis of the local wind flow using the 0.3° ERA5 reanalysis dataset and surface-observed wind data indicates that in western Taiwan, the land-sea breeze is embedded within the synoptic weather type of C3, which is favorable to air pollutant accumulation. However, when the prevailing northeasterly wind is obstructed by the Central Mountain Range, southwestern Taiwan, being situated on the leeside of the mountains, often exhibits the worst air pollution due to stagnant wind conditions.