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Abstract: The purpose was to explore the correlation of air pollutants and meteorological factors with primary glaucoma. Outpatient information and data on air pollutants and meteorological factors were collected from 2017 to 2019. A generalized linear model (GLM) was used to construct single-pollutant models and multiple-pollutant models to analyse the correlations among primary glaucoma visits, air pollutants and meteorological factors in Shenyang. Air pollution had a significant impact on the number of outpatient visits for primary glaucoma in Shenyang. In single-pollutant models and under optimal lag-day conditions, each 10-unit increase in these exposures was associated with the following excess risk (ER) values for daily outpatient visits for primary glaucoma: precipitation (− 4.2%), particulate matter 10 (PM10) (0.7%), SO2 (2.4%), NO2 (4.1%) and O3 (− 1.6%). Every 0.1 mg/m3 increase in CO was associated with a 0.7% ER. The ERs for primary glaucoma in multiple-pollutant models were as follows: NO2 + CO (3.6%), NO2 + SO2 (1.8%), NO2 + PM10 (0.7%), NO2+ CO + PM10 (0.7%), NO2 + SO2 + PM10 (0.6%) and NO2 + SO2 + CO (1.8%). When the concentration of air pollutants increases, the number of outpatient visits by patients diagnosed with primary glaucoma in Shenyang increases correspondingly, and there may be an antagonistic interaction among pollutants. PubDate: 2021-10-16
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Abstract: Many cities in China have invested in the city’s rail transit system to reduce urban air pollution and traffic congestion. Earlier studies rarely compare the effects of rail transit on urban air quality in different cities, providing little guidance to urban planners in solving traffic congestion and air quality. Due to the same opening date, we regard Chengdu Metro Line 4 and Nanchang Metro Line 1 as case studies. This paper attempts to examine the effects of the opening of rail transit on local air quality on the same opening date. Data were collected from 17 monitoring stations distributed along the chosen rail transit lines in both cities from 2015 to 2016 and analyzed using the regression discontinuity design to address the potential endogenous location of subway stations. The results show that subway opening in Nanchang has a better reduction from automobile exhaust than that in Chengdu. Specifically, carbon monoxide pollution, one key tailpipe pollutant, experienced a 10.23% greater reduction after Nanchang Metro Line 1 opened. However, the point estimate for carbon monoxide in Chengdu is 22.42% and statistically significant at the 1% level. Nanchang Metro Line 1 does play an important role in road traffic externalities, but the benefit is not huge enough to change the overall air quality. On the contrary, the opening of the Chengdu Metro Line 4 is unlikely to yield improvements in air quality. PubDate: 2021-10-15
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Abstract: Exposure to air pollutants has been linked to the exacerbation of the respiratory disease. The air quality index and air quality health index (AQHI) were used to evaluate the number of asthma hospitalization attributed to air quality using time-series regression analysis with a distributed lag model. This study was performed from March 2014 to February 2019 in Hamadan, Iran. A generalized linear model (GLM) and distributed lag model (DLM) with the family of Poisson distribution were used to investigate the asthma hospitalization associated with air pollution. The seasonal effect of air pollution was considered in data analysis. Results showed that during the study period, 671 people were hospitalized. The mean (SD) values for AQI, AQHI, and PM2.5 levels were 70.66 (37.77), 3.58 (2.22), and 38.59 (17.43), respectively. The highest adverse effects on asthma hospitalization were observed for AQHI at lag 1 (RR = 1.052, 95% CI 0.998–1.109) and for AQI at lag 1 (RR = 1.002, 95% CI 0.997–1.007), for 1-unit increase of the indexes, and were observed for PM2.5 at lag 0 (RR = 1.005, 95% CI 1.001–1.009) and lag 7 (RR = 1.005, 95% CI 1.001–1.009) for 10 µg/m3 increase in PM2.5 levels. Seasonal analysis results showed that hospitalization in the warm season was significantly higher than that of the cold season for AQI and PM2.5 levels, while RR obtained for AQHI was higher in the cold season. The results confirm the association between air pollutants and an increase in a load of adult asthma hospitalization. To confirm the effects of seasonal variation of PM level and other possible factors (such as meteorological factors) on hospitalization due to asthma, more research will be needed. Our findings provide valuable data to increasing policymakers’ awareness and developing a strategy to improve air quality. PubDate: 2021-10-15
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Abstract: In this study, a validated CFD model is used to analyze the flow field and pollutant distribution in an isolated canyon (street aspect ratio, W/H = 1) by considering different street categories and arrangements of void deck under a perpendicular inflow wind. The results reveal that the street geometry affects significantly the in-canyon flow structures and thus the pollutant distributions. Comparing with the regular street canyon (a main clockwise vortex is obtained therein), the void deck can cause several vortices when a strong stream of air passes through the canyon. It is the most conducive to pollutant removal for the void decks at both buildings, while the construction with void deck at the upstream building causes pollutant accumulation on the windward side. Moreover, a larger high-pollution zone is generated above the elevated road due to the wind recirculation therein, and for the two-level street and the street with depressed road, the weak wind leads to the accumulation of traffic pollutants in the underground space. This study will provide technical support for urban street planning and design to alleviate traffic pollution. PubDate: 2021-10-08
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Abstract: Atmospheric aerosol contamination has caused widespread concern about human and environmental health. However, research about VOCs as an important precursor of secondary aerosols in ambient air is still limited. In this study, VOCs at sites from three typical functional areas in Hefei, China, were monitored using GC–MS/FID. The VOCs in ambient air from different functional areas showed significantly different characteristics. The highest concentrations and the biggest diurnal difference of VOCs were found in the High-tech Zone (industrial area) with serried emission sources. Additionally, lower VOC concentration was observed in Changjiang West Road, the center area of studied city. The VOC concentration in this area is strongly related to other pollutants. The composition of VOCs at all sampling sites showed certain common characteristics, i.e., alkanes, OVOCs, and halogenated hydrocarbons account for more than 75% of the total VOCs’ quality. The High-tech Zone with the highest concentration of VOCs also has the highest proportion of alkanes. Besides, the positive matrix factorization analysis results revealed that vehicle exhaust, LPG volatilization sources, and chemical solvents were the most important VOC emission sources in Hefei. In terms of the contribution of VOC components to the OFP at the three sites, the olefins and alkynes at the Changjiang West Road site and the Science Island site contribute the most significant proportion. In contrast, the OVOCs at the High-tech Zone site contribute the largest proportion. PubDate: 2021-10-06
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Abstract: Air pollution control has become the top priority of China’s “green development” concept since 2013. The Chinese government has enacted a range of policies and statutes to control contaminant emissions and improve air quality. On the basis of the national air quality ground observation database, the spatial and temporal distribution of air quality index value (AQI), fine particulate matter (PM2.5), coarse particles (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) were explored in 336 cities throughout China from 2014 to 2019. AQI and most pollutants (except O3) decreased in concentrations from 2014 to 2019. In 2019, all cities except Henan reached the level 2 of the ambient air quality index, and six cities had a lower ambient air quality index and reached the level 1. Spatially, higher pollutant concentrations were concentrated in large city clusters, whereas the areas with high O3 concentration were found across the country. Furthermore, central heating was shown to have a negative impact on air quality. The observed AQI value, PM2.5, PM10, SO2, NO2, and CO concentrations were highest in north and northwest China and Henan province in central China. The correlations among pollutants suggest that the main sources of pollutants are fossil fuel combustion, industrial production, and motor vehicle emissions. The influence of meteorological factors on air quality, long-distance transportation, and the transformations of pollutants should be explored in future research. PubDate: 2021-10-01
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Abstract: We have investigated the impact of reduced emissions due to COVID-19 lockdown measures in spring 2020 on air quality in Canada’s four largest cities: Toronto, Montreal, Vancouver, and Calgary. Observed daily concentrations of NO2, PM2.5, and O3 during a “pre-lockdown” period (15 February–14 March 2020) and a “lockdown” period (22 March–2 May 2020), when lockdown measures were in full force everywhere in Canada, were compared to the same periods in the previous decade (2010–2019). Higher-than-usual seasonal declines in mean daily NO2 were observed for the pre-lockdown to lockdown periods in 2020. For PM2.5, Montreal was the only city with a higher-than-usual seasonal decline, whereas for O3 all four cities remained within the previous decadal range. In order to isolate the impact of lockdown-related emission changes from other factors such as seasonal changes in meteorology and emissions and meteorological variability, two emission scenarios were performed with the GEM-MACH air quality model. The first was a Business-As-Usual (BAU) scenario with baseline emissions and the second was a more realistic simulation with estimated COVID-19 lockdown emissions. NO2 surface concentrations for the COVID-19 emission scenario decreased by 31 to 34% on average relative to the BAU scenario in the four metropolitan areas. Lower decreases ranging from 6 to 17% were predicted for PM2.5. O3 surface concentrations, on the other hand, showed increases up to a maximum of 21% close to city centers versus slight decreases over the suburbs, but Ox (odd oxygen), like NO2 and PM2.5, decreased as expected over these cities. PubDate: 2021-10-01
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Abstract: The reliability of air quality simulations has a strong dependence on the input emissions inventories, which are associated with various sources of uncertainties, particularly in regions undergoing rapid emission changes where inventories can be ‘out of date’ almost as soon as they are compiled. This work provides a new methodology for updating emissions inventories by source sector using air quality ensemble simulations and observations from a dense monitoring network. It is adopted to determine the short-term trends in carbon monoxide (CO) emissions, an important pollutant and precursor to tropospheric ozone, in a study area centred around Beijing following the implementation of clean air policies. We sample the uncertainties associated with using an a priori emissions inventory for the year 2013 in air quality simulations of 2016, using an atmospheric dispersion model combined with a perturbed emissions ensemble (PEE), which is constructed based on expert-elicited uncertainty ranges for individual source sectors in the inventory. By comparing the simulation outputs with observational constraints, we are able to constrain the emissions of key source sectors relative to those in the a priori emissions inventory. From 2013 to 2016, we find a 44–88% reduction in the transport sector emissions (0.92–4.4×105 Mg in 2016) and a minimum 61% decrease in residential sector emissions (<3.5×105 Mg in 2016) within the study area. We also provide evidence that the night-time fraction of traffic sources in 2016 was higher than that in the 2013 emissions inventory. This study shows the applicability of PEEs and high-resolution observations in providing timely updates of emission estimates by source sector. PubDate: 2021-10-01
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Abstract: Ultraviolet radiation (UV) plays a key role in the photochemistry in the atmosphere. UV has a detrimental impact on human health from direct exposure to sunlight and indirect effect by enhancing photochemical pollutants. Characterizing the levels of solar UV and its role in the production of photochemical pollutants is important to provide awareness of its negative health effects on the human population. Four years (2015–2018) of ultraviolet erythemal radiation (UVER) measurements for Santiago, Chile, were analyzed, and the potential impact of UVER on human health were assessed from both direct and indirect effects. High values of UVER occurred from spring to early autumn, with a maximum of 0.33 Wm−2. Ultraviolet index (UVI) values ≥ 11 were observed in 17% of the days, while UVI ≥ 6 accounts for up to 50% of the days during the observation period. The population in the Metropolitan Region of Santiago (Central, Chile) is exposed to high levels of UVER, increasing the risk of severe sunburn and developing skin cancer. Tropospheric ozone had a positive correlation with ultraviolet erythemal radiation, indicating an increment of 27 ppbv in ozone concentration when UVER levels were above 0.10 Wm−2 (UVI = 4). Incoming sunlight reaches the surface of Central, Chile, energetically enough to cause sunburn and increase the levels of tropospheric ozone from late spring to early autumn. This study provides useful information for public awareness and for adopting strategies to reduce the negative impacts on the human population from direct exposure to sunlight and its role in the production of photochemical pollutants. PubDate: 2021-10-01
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Abstract: Mercury is a toxic pollutant that exists in the atmosphere in several forms, operationally identified according to their chemical and physical characteristics. The problem of atmospheric mercury pollution has recently received increasing attention, as evidenced by the numerous European regulations issued in the last years. The normative question is closely related to the methodological one, as the quantification of the mercury species is strictly linked to the sampling and analysis methods. Due to their different bioavailability, airborne mercury forms detection is fundamental both in outdoor and indoor (i.e., workplace) environments. This paper presents an overview of European legislation on atmospheric mercury pollution, with particular attention to the Italian legislation. Starting from the regulatory protocols, the methodological framework for mercury quantification was reviewed, underlining the limits and the problems of the different methodologies and providing new guidance for the analysis. Regulatory and methodological updates have led to great specificity in mercury quantification, which is distinguished for the outdoor and indoor environments. For workplace environments, all mercury species (i.e., gaseous and particulate mercury) are required to be quantified by the Italian legislation; on the contrary, only gaseous compounds are monitored in outdoor conditions. It hence appears of primary importance that the monitoring operator chooses the sampling and analytical method for mercury sampling and analysis that correctly adheres to the normative regulations. Detailed norms describe how to carry on the monitoring in both outdoor and indoor conditions, preventing the operator’s arbitrariness, which otherwise can lead to airborne mercury underestimation/overestimation. PubDate: 2021-10-01
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Abstract: The contribution of natural sources to PM10 is generally unknown, being sea salt one of these sources, which is especially important in coastal countries. The objective of this work is to evaluate the contribution of sea salt to the PM10 concentration values along the Portuguese coast. For that, four air quality monitoring sites distributed along the coast and with PM10 valid data were selected, using the 2018 reference year. Each monitoring site was characterized in terms of the air mass trajectory patterns associated to the PM10 concentrations, using the HYSPLIT model and cluster analysis. The contribution of sea salt was assessed using data simulated by the WRF-CHIMERE modelling system, used for the air quality operational forecast for Portugal and extensively validated each year. The modelling results for each study site were extracted and processed to calculate the contribution of sea salt to the simulated total PM10 values. The results show that most trajectories came from the Atlantic Ocean, and the higher sea salt concentrations were associated to these trajectories. The sea salt contribution ranged from 7 to 15%, being higher at Atlantic-centre site and lower at the southernmost (Atlantic-Mediterranean) station. This sea salt contribution is expected to be higher during spring and lower during autumn. PubDate: 2021-10-01
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Abstract: Human health deterioration due to industrial air emissions is gaining global attention. These health impacts are coupled mainly with chronic and acute health issues that are persistent in residents in close proximity to the industrial estates. Similarly, the inhabitants of Islamabad Industrial Estate (IEI) are exposed to intense industrial pollutants that have caused respiratory and irritant health issues. This cross-sectional study has compared two groups on deploying 378 close-ended questionnaires at the household level, after adjusting the potential confounders. The groups were framed as per their distance from IEI as ‘Band I’ - residence ≤ 650 m and ‘Band II’ - residence ≥ 650–1300 m. The distances were calculated from the respondent’s residence to the outer digitized boundary (perimeter of IEI), whereas the perimeter was digitized using Google Earth and imported into a Geographical Information System. The results of multiple logistic regression for odds ratios confirmed significant increase in chronic respiratory problems (chronic bronchitis OR 1.93 (1.05–3.55), phlegm OR 2.5 (1.4–4.5), dyspnoea OR 2.18 (0.3–1.81)) and acute irritation issues (eye irritation OR 2.59 (1.63–3.90), throat irritation OR 1.782 (0.876–2.725)) in case of Band I. The same diseases were found in Band II but in less severity; however, their existence remained life-threatening for the locality. The study calls for preventive measures by the local residents, health safety measures by the federal government and relocation of populace to safe areas/sectors. PubDate: 2021-10-01
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Abstract: Indoor particulate matter (PM) concentrations may be high due to indoor PM generation as well as PM introduced from the outdoors in residential buildings. In particular, as building airtight performance has been strengthened to reduce energy consumption, the indoor-generated PM has greatly influenced a person’s overall PM exposure. The indoor activities of residents may generate and resuspend PM, which in turn increases the indoor PM concentration. This study aims to analyze the characteristics of indoor PM generation by activities in a residential building and the removal effect of the ventilation methods. Field measurements were accomplished for indoor PM generation activities in real conditions, such as vacuum cleaning, cooking (fish and pork), air freshener spraying, and scented candle burning in a residential building. As a result, the PM concentration was the highest for broiling fish, with a concentration of 15.714 mg/m3 for PM10 and 13.679 mg/m3 for PM2.5. The decreasing order of the peak concentration for indoor activities was cooking, burning scented candles, vacuuming, and spraying air freshener. Additionally, the residual PM concentration exceeded the standard upper limit even 30 min after most of the PM generation activities ended. Especially, in the cooking activity, with the highest PM generation, PM could not be removed properly even when the range hood was operated. This is because the static pressure loss of the range hood in an air-tightened house and additional air supply or window opening can improve the PM removal performance of the range hood. PubDate: 2021-10-01
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Abstract: Polycyclic aromatic hydrocarbons (PAHs) have a ubiquitous presence in nature and are among the first atmospheric pollutants to be suspected of having carcinogenic and mutagenic nature. For the present study, five representative sites for 16 PAHs were selected for ambient air sampling in Delhi. The concentration of a total of 16 particulate-phase PAHs at all sites was found to be in the range from 30.04 to 222.94 ng/m3 during the sampling period. The concentration of particulate TPAHs was found to be in order as Mukherjee Nagar > Anand Vihar > Rohini > CP > JNU during the sampling period. The mean concentration of gaseous-phase TPAHs at all sites was found to be in the range from 30.16 to 80.16 ng/m3. The mean concentration of gaseous TPAHs was found to be in order as CP > Rohini > Anand Vihar > Mukherjee Nagar > JNU. The health risk values both gaseous- and particulate-PAHs varied from 3.42 × 10−6 (JNU) to 4.96 × 10−6 (Rohini) and 3.43 × 10−5 (JNU) to 7.43 × 10−5 (Mukherjee Nagar) for child and adult respectively. The results of the diagnostic ratio, principal component analysis (PCA), and correlation at different residential sites in Delhi indicated that fossil fuel (diesel and gasoline) and wood burnings were major contributors of total PAHs in all seasons. PubDate: 2021-10-01
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Abstract: Combined air pollution in eastern China is becoming increasingly pronounced, and the air quality index (AQI), which represents the condition of the primary pollutant, can no longer sufficiently evaluate the health risk of air pollutants to humans. In this study, the temporal and spatial distributions of the health risk values (percentage of excess risk, %ER) of four principal air pollutants in six representative cities in China (Beijing, Shanghai, Guangzhou, Chengdu, Shenyang, and Xi’an) from 2014 to 2018 are calculated using an air quality health index (AQHI) that is based on environmental epidemiological research results developed by Hong Kong. The results show that the 90th percentile of the corresponding annual average %ER in these cities decreased by varying degrees. The health risk attributed to air pollution was lower in cities of southern China than those of northern China. The average contributions of PM10 and O3 exceeded 25% and 30%, respectively, which indicates that the combined pollution was severe in the six cities. However, the AQI evaluation method usually underestimates the health risk of air pollution in spring and summer because this method only considers one primary pollutant. In the early spring period (March–May) of Beijing, AQI fell by −24%, but %ER rose by 4% while considering the combined pollution. This substantial difference suggests an urgent demand for corporations and data sharing between the Chinese environmental protection administration and medical authorities to establish and develop a more accurate, scientific, and localized air quality evaluation system. The system developed by China can better assess the health risk caused by combined pollution, which is more adapted to different regions, and provide the public with more accurate advice regarding health risks from air pollution. PubDate: 2021-10-01
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Abstract: Air pollution is currently becoming a significant global environmental issue. The sources of air pollution in Malaysia are mobile or stationary. Motor vehicles are one of the mobile sources. Stationary sources originated from emissions caused by urban development, quarrying and power plants and petrochemical. The most noticeable contaminant in the Peninsular of Malaysia is the particulate matter (PM10), the highest contributor of Air Pollution Index (API) compared to other pollution parameters. The aim of this study is to determine the best loss function between quantile regression (QR) and ordinary least squares (OLS) using boosted regression tree (BRT) for the prediction of PM10 concentration in Alor Setar, Klang and Kota Bharu, Malaysia. Model comparison statistics using coefficient of determination (R2), prediction accuracy (PA), index of agreement (IA), normalized absolute error (NAE) and root mean square error (RMSE) show that QR is slightly better than OLS with the performance of R2 (0.60–0.73), PA (0.78–0.85), IA (0.86–0.92), NAE (0.15–0.17) and RMSE (9.52–22.15) for next-day predictions in BRT model. PubDate: 2021-10-01
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Abstract: PM2.5 pollution used to be severe in China and the government has been devoted to PM2.5 control in recent years. Based on the latest multisource data and advanced algorithms, systematic environmental impact estimation of PM2.5 is achieved to demonstrate its trend and impacts under control policy. Policy validity is proved by a significant decrease in PM2.5 concentration (28%), energy intensity of GDP (13%), particulate matter emission (29%), and PM2.5 exceedance probability (51%) from the nation level. However, it still does not meet the requirement of WHO, and industrial and domestic sources are dominant for PM emission. The disaster risk index of air pollution is proposed to quantify and compare PM2.5 threat in 31 provinces, and risk gradually declines in 24 provinces except steady trend in Xinjiang, Shaanxi, Tianjin, Ningxia, Sichuan, Liaoning, and Tibet. Henan, Shanxi, Xinjiang, Hebei, Shaanxi, Tianjin, Ningxia, Jiangxi, Heilongjiang, and Anhui are identified as 10 high-risk regions with distinct driving factors. Current disease burdens attributable to PM2.5 exposure of provincial capitals in high-risk regions indicate huge health risks and economic losses. The heaviest health burden and economic burden are separately in Tianjin with 604,101 (95% CI: 302,796, 874,058) cases and 5.45% (95% CI: 2.73%, 7.89%) of population, and in Xi’an with 3122.24 (95% CI: 1398.55, 4274.53) million dollars and 2.31% (95% CI: 1.04%, 3.16%) of GDP. Results can provide references for worldwide PM2.5 control: scientific policy, treatment by the whole people and targeted control are crucial; it is urgent to arouse broad consensus on PM2.5 pollution and convert disease burden to health benefit. PubDate: 2021-10-01
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Abstract: It is well-established that traffic-related air pollution has a detrimental impact on health. Much of the focus has been on diesel exhaust emissions due to a rapid increase in vehicle numbers and studies finding that this pollutant is carcinogenic. Unsurprisingly, the highest diesel exposures that the general population experiences are during urban daily commutes; however, few studies have considered professional drivers who are chronically exposed to the pollutant due to their work in transport microenvironments. In this narrative review, we address the literature on professional drivers’ exposure to diesel exhaust and advocate that a modern exposure science approach utilised in commuter personal exposure studies is needed. This type of evaluation will provide a more detailed understanding of the time-activity of professional drivers’ exposures which is required to identify specific interventions to reduce their risk to diesel exhaust emissions. PubDate: 2021-10-01
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Abstract: The associations of particulate matter pollution with the outpatient visits of urticaria, remains poorly studied. This study aimed to evaluate the short-term effects of PM (PM2.5, PM10, and PMc) on daily outpatient visits for urticaria diseases in Lanzhou, China, during 2013–2017. A total of 74,232 outpatient visits for urticaria were collected during the 5 years. A generalized additive Poisson model, based on a sex and age subgroups, was applied to analyze the daily outpatient visits for urticaria diseases. ER and 95% CI were calculated to evaluate the association between every 10 μg/m3 increment of PM pollutants and clinical visits. Increased concentrations of ambient PM2.5, PM10, and PMc were significantly associated with increased numbers of outpatient visits over the 5 years. The largest significant effects for PM2.5, PM10, and PMc on urticaria outpatient visits were observed at lag0, lag6, and lag6, respectively. A 10 μg/m3 increment in concentration of PM2.5, PM10, and PMc were associated with 0.406 (95% CI − 0.093, 0.909), 0.307 (95% CI 0.004, 0.515), and 0.199 (95% CI 0.007, 0.391) increases in urticaria outpatient visits. The younger and elderly populations were susceptible to PM. The association of PM10 and female urticaria outpatient visit was long lag periods, while in males, was short lag periods. PM concentration indicates the increased risk of urticaria. The gaps among both sexes and ages for urticaria should have biological and pollution control implications. PubDate: 2021-10-01
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Abstract: Lack of characterization of indoor pollutant concentrations has been identified as a key barrier for exposure and health estimates. In this study, a field campaign was conducted to measure indoor concentrations of PM1, PM2.5, PM10, CO, and NO2 in a mechanically ventilated building. Statistical method using multivariate linear regression (MLR) and machine learning using random forest (RF) were used and compared to quantify variations in observed concentrations and were then used to predict indoor concentrations for selected pollutants. The two methods were consistent in identifying major predictors for each pollutant. Outdoor particles were the single largest predictors found for PM1 and PM2.5, while indoor environment and occupant-related variables were dominant predictors for PM10, CO, and NO2 in the selected mall. Based on MLR models, outdoor PM accounted for 91%, 64%, and 25% of variations in indoor PM1, PM2.5, and PM10 during opening hours. More than 30% of indoor CO variations were related to time-dependent activities. Nearly 50% of the indoor NO2 variations were explained by temperature and relative humidity. Both models are useful in predicting indoor concentrations. In the tenfold cross validation, RF models showed high prediction capability for PM1 (R2 > 0.9) and moderate (R2: 0.5 ~ 0.7) for the other four pollutants in both periods except for PM10 during non-opening hours (R2 = 0.3). MLR models exhibited comparable prediction power for PM1 and PM2.5, but generally lower for PM10 and gases. Availability of parameter information in modern cities facilitates the application of such models on large scale, based on proper validation, for better characterizing of indoor air quality. PubDate: 2021-09-29
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