Annual Mean Concentrations Of PM2 Research Articles

Exposure to high levels of PM2.5 and PM10 in the metropolis of Tehran and the associated health risks during 2016–2017

This study provides the daily, seasonal and annual variations and the related human health risk assessment from exposure to PM2.5 and PM10 in the ambient air of Tehran from January 2016 to December 2017. The hourly PM2.5 and PM10 data of ten selected air quality monitoring stations was acquired from Tehran air quality control center. The results showed that, annual mean concentrations of PM2.5 and PM10 in the selected stations varied from 22.6 to 39.5 μg/m3 and from 62.5 to 104.3 μg/m3, respectively. However, Tehran citizens were exposed to concentrations of annual PM2.5 and PM10 exceeding the WHO air quality guideline (AQG), US Environmental Protection Agency (USEPA) and Iranian standard levels during the study period. The mean of hazard quotient (HQ) for PM2.5 (6.3) and PM10 (1.6) in all age groups were >1, indicating an unacceptable risk for human health. Also, the mean of Excess Lifetime Cancer Risk (ELCRs) for PM2.5 in different age groups in 2016 and 2017 varied from 3.7 × 10−6 to 276.9 × 10−6 and from 4 × 10−6 to 306.4 × 10−6, respectively, which exceeds the limit value set by the USEPA and WHO. Based on this study, ambient air can be a potential source for exposure to PM10 and PM2.5 and increase the risk of respiratory diseases and cardiovascular problems among exposed people. Therefore, proper control policies are recommended to protect public health in this metropolitan area.

우리나라 미세먼지 농도 추이와 고농도 발생 현황

The publicʼs concern on ambient PM10 has increased sharply since 2013. To check whether the concern is related the PM10 concentration, the trends of (1) the annual mean PM10 concentration, (2) the frequency by the PM10 concentration interval, and (3) the high concentration occurrence duration time are studied. It is found that all three indicators have decreased between 2001 and 2017. For example, the annual mean PM10 concentration decreased from 71 μg/m³ in 2001 to 44 μg/m³ in 2017 in Seoul. Generally, the frequency of the PM10 concentration over 50 μg/m³ has decreased while that less than 20 μg/m³ has changed little. Thus, the frequency between 20 and 50 μg/m³ has increased. However, different trends in the PM10 concentration, frequency by concentration level and frequency over 50 μg/m³ for duration are observed among the administrative districts. To reduce the annual average concentration of PM10, there should be more measures to reduce the frequency of PM10 concentration between 20 and 50 μg/m³ as well as over 50 μg/m³ for increasing the frequency of low PM10 below 20 μg/m³.

Spatial and Temporal Variations of Gaseous and Particulate Pollutants in Six Sites in Tibet, China, during 2016–2017

ABSTRACT Long-term air quality data with high temporal and spatial resolutions are necessary to understand some processes influencing air quality and corresponding environmental and health effects. In this study, spatiotemporal variations of PM2.5, PM10, SO2, NO2, CO, and O3 were investigated over a one-year period (June 2016–May 2017) at six sites of the Tibetan Plateau (TP). The annual mean concentrations of PM2.5 in all cities except Nagchu were below the Grade II standard (35 µg m–3), and the values in Nagri and Nyingchi were even less than the Grade I standard (15 µg m–3). PM10 concentrations showed similar distribution pattern with PM2.5. Evident seasonal variations of PM2.5, PM10, SO2, NO2, and CO concentrations were observed, with the highest seasonal average value being in winter followed by fall, spring, and summer, in descending order. By contrast, the 8-h O3 concentration showed an opposite seasonal variation because the O3 depended on lots of factors such as stratospheric incursions, weather conditions, and intensity of solar radiation. The diurnal trends of PM2.5, PM10, SO2, NO2, and CO concentrations in study region generally showed a flat “W” shape with two peaks occurring around noon (10:00–12:00) and midnight (21:00–23:00); these peaks were found to be affected by emission sources and weather conditions. However, the O3 concentration trends did not significantly differ among the six regions, with the maximum concentration being in the afternoon. In sum, cities on the TP showed slightly higher pollution levels in regions affected by anthropogenic activities such as Lhasa and Nagchu, whereas other cities showed good air quality. Beside long-range transport pollutants from surrounding regions, local emissions (e.g., biomass burning, religious activities) also contributed much to the atmospheric pollutants. This study provides a basis for the formulation of future urban air pollution control measures on the TP.

Probabilistic Automatic Outlier Detection for Surface Air Quality Measurements from the China National Environmental Monitoring Network

Although quality assurance and quality control procedures are routinely applied in most air quality networks, outliers can still occur due to instrument malfunctions, the influence of harsh environments and the limitation of measuring methods. Such outliers pose challenges for data-powered applications such as data assimilation, statistical analysis of pollution characteristics and ensemble forecasting. Here, a fully automatic outlier detection method was developed based on the probability of residuals, which are the discrepancies between the observed and the estimated concentration values. The estimation can be conducted using filtering—or regressions when appropriate—to discriminate four types of outliers characterized by temporal and spatial inconsistency, instrument-induced low variances, periodic calibration exceptions, and less PM10 than PM2.5 in concentration observations, respectively. This probabilistic method was applied to detect all four types of outliers in hourly surface measurements of six pollutants (PM2.5, PM10, SO2, NO2, CO and O3) from 1436 stations of the China National Environmental Monitoring Network during 2014–16. Among the measurements, 0.65%–5.68% are marked as outliers, with PM10 and CO more prone to outliers. Our method successfully identifies a trend of decreasing outliers from 2014 to 2016, which corresponds to known improvements in the quality assurance and quality control procedures of the China National Environmental Monitoring Network. The outliers can have a significant impact on the annual mean concentrations of PM2.5, with differences exceeding 10 μg m−3 at 66 sites.

Characteristics of air pollution events over Hotan Prefecture at the southwestern edge of Taklimakan Desert, China

Hotan Prefecture is located at the southwestern edge of Taklimakan Desert, the world’s largest shifting sand desert, of China. The desert is one of the main sources for frequent sand-dust weather events which strongly affect the air quality of Hotan Prefecture. Although this region is characterized by the highest annual mean PM10 concentration values that are routinely recorded by environmental monitoring stations across China, both this phenomenon and its underlying causes have not been adequately addressed in previous researches. Reliable pollutant PM10 data are currently retrieved using a tapered element oscillating microbalance (TEOM) 1400a, a direct real-time monitor, while additional concentration values including for PM2.5, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and ozone (O3) have been collected in recent years by the Hotan Environmental Monitoring Station. Based on these data, this paper presents a comparison of the influences of different kinds of sand-dust weather events on PM10 (or PM2.5) as well as the concentrations of other gaseous pollutants in Hotan Prefecture. It is revealed that the highest monthly average PM10 concentrations are observed in the spring because of the frequent occurrence of three distinct kinds of sand-dust weather events at this time, including dust storms, blowing dust and floating dust. The floating dust makes the most significant contribution to PM10 (or PM2.5) concentration in this region, a result that differs from eastern Chinese cities where the heaviest PM10 pollution occurs usually in winter and air pollution results from the excess emission of local anthropogenic pollutants. It is also shown that PM10 concentration varies within typical dust storms. PM10 concentrations vary among 20 dust storm events within Hotan Prefecture, and the hourly mean concentrations tend to sharply increase initially then slowly decreasing over time. Data collected from cities in eastern China show the opposite with the hourly mean PM10 (or PM2.5) concentration tending to slowly increase then sharply decrease during heavy air pollution due to the excess emission of local anthropogenic pollutants. It is also found that the concentration of gaseous pollutants during sand-dust weather events tends to be lower than those cases under clear sky conditions. This indicates that these dust events effectively remove and rapidly diffuse gaseous pollutants. The analysis also shows that the concentration of SO2 decreases gradually at the onset of all three kinds of sand-dust weather events because of rapidly increasing wind velocity and the development of favorable atmospheric conditions for diffusion. In contrast, changes in O3 and NO2 concentrations conformed to the opposite pattern during all three kinds of sand-dust weather events within this region, implying the inter transformation of these gas species during these events.

중국 초미세먼지 현황 및 정책 동향

The emission of air pollutants in China has increased rapidly as its economy expanded over the last decades. The Chinese government has recently acknowledged the seriousness of the resulting air pollution and is trying to improve air quality in many ways. Here, we review the air quality control and management policies in China, one of our closest neighbors, because these policies may also influence the air quality in Korea. This study examined the recent policies on PM2.5 reduction and analyzed the variation in air quality and air pollutant emissions in China. The ambient air quality and emission standards in China have been strengthened, based on China’s Air Pollution Prevention and Control Action Plan of 2013. As a result, the annual mean concentration of PM2.5 in 2015 in 74 large Chinese cities declined by 23.6% compared with 2013 values. Coal consumption in China also has been reduced by more than 10% per year since 2013. Furthermore, the laws controlling atmospheric emissions were revised again in 2016, and an air pollution forecasting and warning system was implemented to help manage air pollution problems. At present, the Chinese government is trying to evaluate its policies on PM2.5 and find a new paradigm to mitigate ongoing PM2.5 pollution. In this context, a joint study between Korea and China has been initiated to investigate the characteristics and sources of ambient PM2.5 and to identify factors contributing to the high PM2.5 concentrations in northeast China. We expect that this academic collaboration will benefit both countries in their search for new policies for PM2.5 reduction.

Does exposure to PM10 decrease age at menarche?

BackgroundThere has been a consistent decrease in age at menarche in South Korea. A potential risk factor for early menarche is exposure to particulate matter (PM), because endocrine-disrupting compounds emitted into air from anthropogenic sources may be incorporated into PM. The objective of this study was to examine the association between pre-menarcheal exposure to PM ≤ 10 μm in diameter (PM10) and age at menarche in adolescents of South Korea using Korea National Health and Nutrition Examination Survey (KNHANES) 2010–2012 data. MethodsWe used self-reported age at menarche of 639 girls aged 13–17 years in this study. The cut-off age for early menarche was set to 12 years. Based on each subject's address, 1-year, 2-year, and 3-year averages of annual mean PM10 concentrations (models 1–3) were linked to KNHANES. Models were adjusted for body mass index (BMI), city size, household income level, maternal age at menarche, and second-hand smoke exposure at home. SURVEYREG and SURVEYLOGISTIC procedures were used to address the complex survey design of KNHANES. ResultsOverall analysis showed that exposure to PM10 has a significant effect on decreasing age at menarche. Multiple linear regression results suggested that each 1 μg/m3 increase in 1-year, 2-year, 3-year averages of annual mean PM10 concentrations accelerated age at menarche by 0.046 years (95% CI: −0.064, −0.027; p < .0001), 0.038 years (95% CI: −0.059, −0.018; p = 0.0003),and 0.031 years (95% CI: −0.047, −0.015; p = 0.0002), respectively. Adjusted ORs for a 1 μg/m3 increase in PM10 concentration were 1.08 (95% CI: 1.04 −1.12) for model 1, 1.06 (95% CI: 1.02 −1.10) for model 2, and 1.05 (95% CI: 1.01 −1.09) for model 3. ConclusionOur findings suggest that elevated PM10 concentration can decrease age at menarche. This is the first study that investigates the association between exposure to PM10 and age at menarche using a nationally representative sample of Koreans.

Status and chemical characteristics of ambient PM2.5 pollutions in China: a review

The ambient fine particulate matter is a considerable hazard to human health and the surrounding environment of the majority of Chinese cities. This article reviews the status of air pollution, especially PM2.5, in 21 cities of China, on the basis of their status, chemical characteristics, and regulations data collected from the published literature. The observed results show Zhengzhou, Yulin, Jinan, Qingdao, and Changchun as significantly polluted cities where the annual mean concentration of PM2.5 was noted to be greater than 120 µg m−3. However, some cities such as Xiamen, Hong Kong, Shenzhen, and Jinchang reported average annual PM2.5 concentrations less than 40 µg m−3. In general, the results of spatial distribution reported that the cities of the east, north, and northeast China are highly polluted. According to the average mass of PM2.5 in maximum cities of China, the sum of sulfate, nitrate and ammonium (SNA) and organic matter (OM) contributed over 40 and 35%, respectively. The higher amount of SNA and OM in PM2.5 results from heavy traffic or vehicle emission and burning solid fuel utilized in most part of China. A proposed systemic approach to address the PM2.5 in China can improve the quality of ambient atmosphere.

Long-term trends and health impact of PM2.5 and O3 in Tehran, Iran, 2006–2015

The main objectives of this study were (1) investigation of the temporal variations of ambient fine particulate matter (PM2.5) and ground level ozone (O3) concentrations in Tehran megacity, the capital and most populous city in Iran, over a 10-year period from 2006 to 2015, and (2) estimation of their long-term health effects including all-cause and cause-specific mortality. For the first goal, the data of PM2.5 and O3 concentrations, measured at 21 regulatory monitoring network stations in Tehran, were obtained and the temporal trends were investigated. The health impact assessment of PM2.5 and O3 was performed using the World Health Organization (WHO) AirQ+ software updated in 2016 by WHO European Centre for Environment and Health. Local baseline incidences in Tehran level were used to better reveal the health effects associated with PM2.5 and O3. Our study showed that over 2006–2015, annual mean concentrations of PM2.5 and O3 varied from 24.7 to 38.8 μg m−3 and 35.4 to 76.0 μg m−3, respectively, and were significantly declining in the recent 6 years (2010–2015) for PM2.5 and 8 years (2008–2015) for O3. However, Tehran citizens were exposed to concentrations of annual PM2.5 exceeding the WHO air quality guideline (WHO AQG) (10 μg m−3), U.S. EPA and Iranian standard levels (12 μg m−3) during entire study period. We estimated that long-term exposure to ambient PM2.5 contributed to between 24.5% and 36.2% of mortality from cerebrovascular disease (stroke), 19.8% and 24.1% from ischemic heart disease (IHD), 13.6% and 19.2% from lung cancer (LC), 10.7% and 15.3% from chronic obstructive pulmonary disease (COPD), 15.0% and 25.2% from acute lower respiratory infection (ALRI), and 7.6% and 11.3% from all-cause annual mortality in the time period. We further estimated that deaths from IHD accounted for most of mortality attributable to long-term exposure to PM2.5. The years of life lost (YLL) attributable to PM2.5 was estimated to vary from 67,970 to 106,706 during the study period. In addition, long-term exposure to O3 was estimated to be responsible for 0.9% to 2.3% of mortality from respiratory diseases. Overall, long-term exposure to ambient PM2.5 and O3 contributed substantially to mortality in Tehran megacity. Air pollution is a modifiable risk factor. Appropriate sustainable control policies are recommended to protect public health.

Spatiotemporal Characteristics of Air Pollutants (PM10, PM2.5, SO2, NO2, O3, and CO) in the Inland Basin City of Chengdu, Southwest China

Most cities in China are experiencing severe air pollution due to rapid economic development and accelerated urbanization. Long-term air pollution data with high temporal and spatial resolutions are needed to support research into physical and chemical processes that affect air quality, and the corresponding health risks. For the first time, data on PM10, PM2.5, SO2, NO2, O3 and CO concentrations in 23 ambient air quality automatic monitoring stations and routine meteorological were collected between January 2014 and December 2016 to determine the spatial and temporal variation in these pollutants and influencing factors in Chengdu. The annual mean concentrations of PM2.5 and PM10 exceeded the standard of Chinese Ambient Air Quality and World Health Organization guidelines standards at all of the stations. The concentrations of PM10, PM2.5, SO2 and CO decreased from 2014 to 2016, and the NO2 level was stable, whereas the O3 level increased markedly during this period. The air pollution characteristics in Chengdu showed simultaneously high PM concentrations and O3. High PM concentrations were mainly observed in the middle region of Chengdu and may have been due to the joint effects of industrial and vehicle emissions. Ozone pollution was mainly due to vehicle emissions in the downtown area, and industry had a more important effect on O3 in the northern area with fewer vehicles. The concentrations of PM10, PM2.5, NO2 and CO were highest in winter and lowest in summer; the highest SO2 concentration was also observed in winter and was lowest in autumn, whereas the O3 concentration peaked in summer. Haze pollution can easily form under the weather conditions of static wind, low temperature and relative humidity, and high surface pressure inside Chengdu. In contrast, severe ozone pollution is often associated with high temperature.

Long-Term Exposure to Traffic Related Noise and Incidence of Diabetes: A Danish Nurse Cohort Study

Background/Aim: Well-established risk factors for diabetes include diet, body mass index and physical activity, all of which are individually modifiable factors. However, recent evidence suggests that environmental factors including road traffic noise and air pollution may affect the risk of developing diabetes. Here we examine whether road traffic noise is associated with diabetes incidence, when accounting for air pollution exposure. Methods: 28,731 female nurses from the Danish Nurse cohort (&gt;44 years old at recruitment in 1993 or 1999) were linked to the Danish Diabetes Register with information on incidence of diabetes from 1995 until 2013. The annual mean weighted levels of 24-hour average road traffic noise (Lden) were modeled with Nord2000. Annual mean concentrations of PM2.5 at residence were modeled with Danish AirGIS system. Cox proportional hazards regression models with age as underlying time was used to examine the association between annual mean Lden at the study baseline (1995 or 1999) and the incidence of diabetes in a model adjusted for lifestyle factors and additionally, for annual mean PM2.5 concentration at the study baseline (1995 or 1999). Results: Of 23,169 nurses free of diabetes at the cohort enrolment, 1,099 developed diabetes during a mean follow-up of 15.2 years. The diabetes risk was increased among those exposed to high (&gt;57 dB) when compared to low (≤ 47 dB) Lden in crude model (hazard ratio (HR); 1.25 (95% confidence interval (CI): 1.06-1.47), and adjusted for diabetes risk factors (1.18; 1.00-1.39). However, the effect of Lden diminished (HR 1.03; 0.86-1.24) when adjusting for PM2.5. In the fully adjusted model, an interquartile range (3.89 µg/m3) increase in PM2.5 was associated with 18% (HR: 1.18, 95% CI: 1.09-1.29) increase in diabetes risk. Conclusions: We detected association between road traffic noise and diabetes risk, but which disappeared after adjustment for PM2.5.

Air Pollution and Cognitive Development in Children of United Kingdom Millennium Cohort Study

Background/Aim: There is increasing interest in the possible link between air pollution and cognitive development, but the evidence remains inconclusive. We investigated the association between long-term exposure to air pollution and cognitive development in children in the United Kingdom’s Millennium Cohort Study (MCS). Methods: The MCS follows children born in 2000-01, ~13,000 of whom (England 63%, Wales 15%, Scotland 11% and Northern Ireland 10%) were assessed for cognitive development. We linked each child to the annual mean concentration of PM2.5, PM10, NO2 and SO2 at the postcode centroid for his/her home address at the time of assessment. Cognitive function was assessed at age 3, 5 and 7 years using the British Ability Scales (BAS) and National Foundation for Education Research methods. Age-normalized T-scores of each domain (two domains at age 3, three each at ages 5 and 7), and their changes over time, were analysed by multiple linear regression with adjustment for sex, ethnicity, socioeconomic status and country/region, and allowing for clustering by local authority or district. Results: In England, a 10µg/m3 increase in PM2.5, PM10 and NO2 was associated with a change of -5.2 (95%CI: -7.4, -2.9), -3.7 (-5.2, -2.3) and -1.1 (-1.6, -0.5) in Naming Vocabulary score at age 5, but small (not statistically significant) changes in the two other domains. At age 7, a 10µg/m3 increase in PM2.5 was associated with a change of -2.8 (-5.5, -0.1) in Pattern Construction scores, but no other pollutant-outcome combination showed evidence of adverse association. Results for Scotland were broadly similar to those for England, but somewhat different in Wales and Northern Ireland. Conclusions: Higher PM2.5, PM10 and NO2 concentration was associated with lower cognitive ability in selected cognitive assessments at ages 5 and 7, but not consistently so in all countries of the United Kingdom and at all ages.

Seasonal characteristics, formation mechanisms and source origins of PM&amp;lt;sub&amp;gt;2.5&amp;lt;/sub&amp;gt; in two megacities in Sichuan Basin, China

Abstract. To investigate the characteristics of PM2.5 and its major chemical components, formation mechanisms, and geographical origins in the two megacities, Chengdu (CD) and Chongqing (CQ), in Sichuan Basin of southwest China, daily PM2.5 samples were collected simultaneously at one urban site in each city for four consecutive seasons from autumn 2014 to summer 2015. Annual mean concentrations of PM2.5 were 67.0 ± 43.4 and 70.9 ± 41.4 µg m−3 at CD and CQ, respectively. Secondary inorganic aerosol (SNA) and organic matter (OM) accounted for 41.1 and 26.1 % of PM2.5 mass at CD, and 37.4 and 29.6 % at CQ, respectively. Seasonal variations of PM2.5 and major chemical components were significant, usually with the highest mass concentration in winter and the lowest in summer. Daily PM2.5 concentration exceeded the national air quality standard on 30 % of the sampling days at both sites, and most of the pollution events were at the regional scale within the basin formed under stagnant meteorological conditions. The concentrations of carbonaceous components were higher at CQ than CD, likely partially caused by emissions from the large number of motorcycles and the spraying processes used during automobile production in CQ. Heterogeneous reactions probably played an important role in the formation of SO42−, while both homogeneous and heterogeneous reactions contributed to the formation of NO3−. Geographical origins of emissions sources contributing to high PM2.5 masses at both sites were identified to be mainly distributed within the basin based on potential source contribution function (PSCF) analysis.

Estimated effects of air pollution and space-time-activity on cardiopulmonary outcomes in healthy adults: A repeated measures study

BackgroundExposure to air pollution is known to affect both short and long-term outcomes of the cardiopulmonary system; however, findings on short-term outcomes have been inconsistent and often from isolated and long-term rather than coexisting and short-term exposures, and among susceptible/unhealthy rather than healthy populations. AimsWe aimed to investigate separately the annual, daily and daily space-time-activity-weighted effect of ambient air pollution, as well as confounding or modification by other environmental (including noise) or space-time-activity (including total daily physical activity) exposures, on cardiopulmonary outcomes in healthy adults. MethodsParticipants (N=57: 54% female) had indicators of cardiopulmonary outcomes [blood pressure (BP), pulse (HR) and heart rate variability (HRV {SDNN}), and lung function (spirometry {FEV1, FVC, SUM})] measured on four different mornings (at least five days apart) in a clinical setting between 2011 and 2014. Spatiotemporal ESCAPE-LUR models were used to estimate daily and annual air pollution exposures (including PM10, PMCoarse, but not Ozone {derived from closest station}) at participant residential and occupational addresses. Participants' time-activity diaries indicated time spent at either address to allow daily space-time-activity-weighted estimates, and capture total daily physical activity (total-PA {as metabolic-equivalents-of-task, METs}), in the three days preceding health measurements. Multivariate-adjusted linear mixed-effects models (using either annual or daily estimates) were adjusted for possible environmental confounders or mediators including levels of ambient noise and greenness. Causal mediation analysis was also performed separately considering these factors as well as total-PA. All presented models are controlled by age, height, sex and season. ResultsAn increase in 5μg/m3 of daily space-time-activity-weighted PMCoarse exposure was statistically significantly associated with a 4.1% reduction in total heart rate variability (SDNN; p=0.01), and remained robust after adjusting for suspected confounders [except for occupational-address noise (β=−2.7, p=0.20)]. An increase in 10ppb of annual mean Ozone concentration at the residential address was statistically significantly associated with an increase in diastolic BP of 6.4mmHg (p<0.01), which lost statistical significance when substituted with daily space-time-activity-weighted estimates. As for pulmonary function, an increase in 10μg/m3 of annual mean PM10 concentration at the residential address was significantly associated with a 0.3% reduction in FVC (p<0.01) and a 0.5% reduction in SUM (p<0.04), for which again significance was lost when substituted for daily space-time-activity-weighted estimates These associations with pulmonary function remained robust after adjusting for suspected confounders, including annual Ozone, as well as total-PA and bioaerosol (pollen and fungal spore) levels (but not residential-neighborhood greenness {β=−0.22, p=0.09; β=−0.34, p=0.15, respectively}). Multilevel mediation analysis indicated that the proportion mediated as a direct effect on cardiopulmonary outcomes by suspected confounders (including total-PA, residential-neighborhood greenness, and occupational-address noise level) from primary exposures (including PM10, PMCoarse, and O3) was not statistically significant. ConclusionOur findings suggest that increased daily space-time-activity-weighted PMCoarse exposure levels significantly adversely affect cardiac autonomic modulation (as reduced total HRV) among healthy adults. Additionally, increased annual levels at the residential address of Ozone and PM10 significantly increase diastolic blood pressure and reduce lung function, respectively, among healthy adults. These associations typically remained robust when adjusting for suspected confounders. Occupational-address noise and residential-neighborhood greenness levels, however, were seen as mediators of cardiovascular and pulmonary outcomes, respectively. Total daily physical activity was not seen as a mediator of any of the studied outcomes, which supports the promotion of active mobility within cities.

Levels, Sources, Markers and Health Risks of Heavy Metals in PM2.5 Over a Typical Mining and Metallurgical City of Central China

To investigate the pollution characteristics, sources and health risk assessment of various elements in PM2.5 of Huangshi city, 54 samples were collected from March 2012 to February 2013. The composition and characteristic of sixteen elements (Mg, Al, Ca, Ti, Cr, Mn, Cu, Zn, V, Fe, As, Pb, Cd, Co, Ni and W) were analyzed by high-sensitivity X-ray fluorescence (XRF). The result showed that the annual mean concentration of PM2.5 was 104.4 μg/m3, far exceeding the secondary level of Ambient Air Quality Standard of China (annual average limit 35 μg/m3). Element W has the highest annual concentration, followed by Zn, Pb and As. Compared with the concentration limit of National Ambient Air Quality Standard of China, Cd and As in Huangshi were 4.3 times and 32.8 times higher, respectively, than national standard. The concentration of most elements has distinct seasonal characteristic which is higher in winter and lower in summer. Enrichment factor (EF) analysis indicates that W, Fe, Cd, As, Pb, Zn, Cu, Cr, Co and Ni are extremely enriched in PM2.5, Ca, Mg and Mn are highly enriched, and V is significant enriched. EF of Ti is less than 2, suggesting minimal pollution. Positive matrix factorization (PMF) analysis indicates that Ca, Ti and Al are associated with fugitive dust, and As is associated with coal-fired industrial activity. W, Cr, Cd, V and Ni are originated from chemical and metallurgical industry activities. Pb, Zn, Cu and Mg are derived from vehicle emissions. The results of the human health risk assessment model show that As may pose great non-carcinogenic risk to children and adults. Cr and As have a higher carcinogenic risk for adults, and Cr has a higher carcinogenic risk for children, and other toxic metals are in relatively safe range.

The Impact of a Severe Drought on Dust Lifting in California\u2019s Owens Lake Area

Mineral dust aerosols are responsible for some of the largest sources of uncertainties in our current understanding of climate change. Here we show that a severe drought is having a significant impact in one of largest sources of mineral dust aerosols of the U.S., the Owens Lake area in California’s southwest. Measurements of aerosol concentration (PM2.5 particle matter) in the Owens Lake salty playa show that the annual mean concentration of PM2.5 aerosol has been increasing steadily since the beginning of the current drought, with periods of high aerosol concentration increasing from 4 months in 2013 to 9 months in 2015. Interestingly, the PM2.5 aerosol concentration usually increases abruptly from less than ~0.05 mg/m3 to ~0.25 mg/m3. This occurs when saltation events break salt crusts produced by the efflorescence of brine in the salty playa. The brine is produced by either rainfall or runoff water. Based on this observation, we hypothesize that there is an upper limit of ~0.25 mg/m3 in the annual mean PM2.5 aerosols concentration in the Owens Lake basin that might limit the impact of mineral dust aerosols on climate. Indeed, the upper annual limit of ~0.25 mg/m3 has been nearly reached during the current drought.

Spatial and temporal variation of particulate matter and gaseous pollutants in China during 2014–2016

China is experiencing severe air pollution due to rapid economic development and accelerated urbanization. High-resolution temporal and spatial air pollution data are imperative to understand the physical and chemical processes affecting air quality of China. The data of PM2.5, PM10, SO2, CO, NO2, and O3 in 187 Chinese cities during January 2014 and November 2016 were collected to uncover the spatial and temporal variation of the pollutants in China. The annual mean concentrations of PM2.5 exceeded the Grade I standard of Chinese Ambient Air Quality (CAAQS) for all of the cities except several cities in Hainan, and more than 100 cities exceeded the CAAQS Grade II standard. The concentrations of PM2.5, PM10, SO2, CO, and NO2 decreased from 2014 to 2016, whereas the O3 level increased dramatically during this period. The concentrations of PM2.5, PM10, SO2, CO and NO2 exhibited the highest levels in winter and the lowest in summer, and evidently decreased from 2014 to 2016, whereas the O3 concentration peaked in spring and summer, and dramatically increased from 2014 to 2016. The non-attainment ratios were highest in winters, while high pollution days were also frequently observed in the Southeast region in autumn and in the Northwest region in spring. Pearson correlation analysis indicated that all of the pollutants exhibited significant correlation one another. PM10 was a major pollutant affecting the air quality of China in all of the seasons. Both SO2 and NO2 exerted significantly adverse effects on the air quality in spring and autumn, but CO played an important role on the air quality in winter. O3 was found to be the dominant species among the pollutants affecting the air quality in summer, suggesting that photochemical O3 formation should be paid more attention to improve the air quality in summer. The results of geographical weight regression (GWR) showed that more significant correlations among the pollutants and the highest air quality index (AQI) appeared in the south of China. The impacts of PM10 and NO2 on the air quality increased from the east to the west of China, while SO2 and O3 exhibited the opposite variation. The data presented herein supplied an important support for the future source apportionment and intra- and inter-regional transport modeling of pollutants.

Ambient particulate matter and carbon monoxide at an urban site of India: Influence of anthropogenic emissions and dust storms

Continuous measurements of PM2.5, PM10 and CO were conducted at an urban site of Udaipur in India from April 2011 to March 2012. The annual mean concentrations of PM2.5, PM10 and CO were 42 ± 17 μg m−3, 114 ± 31 μg m−3 and 343 ± 136 ppbv, respectively. Concentrations of both particulate and CO showed high values during winter/pre-monsoon (dry) period and lowest in the monsoon season (wet). Local anthropogenic emission and long-range transport from open biomass burning sources along with favourable synoptic meteorology led to elevated levels of pollutants in the dry season. However, higher values of PM10/PM2.5 ratio during pre-monsoon season were caused by the episodes of dust storm. In the monsoon season, flow of cleaner air, rainfall and negligible emissions from biomass burning resulted in the lowest levels of pollutants. The concentrations of PM2.5, PM10 and CO showed highest values during morning and evening rush hours, while lowest in the afternoon hours. In winter season, reductions of PM2.5, CO and PM10 during weekends were highest of 15%, 13% and 9%, respectively. In each season, the highest PM2.5/PM10 ratio coincided with the highest concentrations of pollutants (CO and NOX) indicating predominant emissions from anthropogenic sources. Exceptionally high concentrations of PM10 during the episode of dust storm were due to transport from the Arabian Peninsula and Thar Desert. Up to ∼32% enhancements of PM10 were observed during strong dust storms. Relatively low levels of O3 and NOx during the storm periods indicate the role of heterogeneous removal.

Assessment of PM2.5 chemical compositions in Delhi: primary vs secondary emissions and contribution to light extinction coefficient and visibility degradation

Haze-fog conditions over northern India are associated with visibility degradation and severe attenuation of solar radiation by airborne particles with various chemical compositions. PM2.5 samples have been collected in Delhi, India from December 2011 to November 2012 and analyzed for carbonaceous and inorganic species. PM10 measurements were made simultaneously such that PM10–2.5 could be estimated by difference. This study analyzes the temporal variation of PM2.5 and carbonaceous particles (CP), focusing on identification of the primary and secondary aerosol emissions, estimations of light extinction coefficient (bext) and the contributions by the major PM2.5 chemical components. The annual mean concentrations of PM2.5, organic carbon (OC), elemental carbon (EC) and PM10–2.5 were found to be 153.6 ± 59.8, 33.5 ± 15.9, 6.9 ± 3.9 and 91.1 ± 99.9 μg m−3, respectively. Total CP, secondary organic aerosols and major anions (e.g., SO4 2− and NO3 −) maximize during the post-monsoon and winter due to fossil fuel combustion and biomass burning. PM10–2.5 is more abundant during the pre-monsoon and post-monsoon. The OC/EC varies from 2.45 to 9.26 (mean of 5.18 ± 1.47), indicating the influence of multiple combustion sources. The bext exhibits highest values (910 ± 280 and 1221 ± 371 Mm−1) in post-monsoon and winter and lowest in monsoon (363 ± 110 and 457 ± 133 Mm−1) as estimated via the original and revised IMPROVE algorithms, respectively. Organic matter (OM =1.6 × OC) accounts for ~39 % and ~48 % of the bext, followed by (NH4)2SO4 (~21 % and ~24 %) and EC (~13 % and ~10 %), according to the original and revised algorithms, respectively. The bext estimates via the two IMPROVE versions are highly correlated (R2 = 0.95, root mean square error = 38 % and mean bias error = 28 %) and are strongly related to visibility impairment (r = −0.72), mostly associated with anthropogenic rather than natural PM contributions. Therefore, reduction of CP and precursor gas emissions represents an urgent opportunity for air quality improvement across Delhi.

Spatial and seasonal variations of gaseous and particulate matter pollutants in 31 provincial capital cities, China

In order to know air pollution situation and their health, environmental, and climate effects, the air quality data with high temporal and spatial resolutions are essential. The spatial and seasonal variations of six criteria pollutants were investigated in 31 provincial capital cities between April 2014 and March 2015 using hourly mean air quality monitoring data, and the cities were classified by cluster analysis based on annual variations of air pollutants. The annual mean concentrations of PM2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) and PM10 (particulate matter with aerodynamic diameter less than 10 μm) were high for all cities, which exceeded Chinese Ambient Air Quality Standards (CAAQS) Grade I standards. Only Fuzhou, Haikou, Kunming, and Lasa met Grade II standards for PM2.5 and PM10. Additionally, elevated SO2 concentration was observed in northern cities, especially in winter. However, the seasonal variation of O3 was opposite to other pollutants with the lowest concentrations in the winter and the highest in the summer. Winter domestic heating has significant impact on urban air quality, especially SO2 and PM10.