Concentrations Of Criteria Air Pollutants Research Articles

Combating air pollution significantly reduced air mercury concentrations in China

Abstract In the past decade, China has motivated proactive emission control measures that have successfully reduced emissions of many air pollutants. For atmospheric mercury, a globally transported neurotoxin, much less is known about the long-term changes of its concentrations and anthropogenic emissions in China. In this study, over a decade of continuous observations at four Chinese sites show that gaseous elemental mercury (GEM) concentrations continuously increased until the early 2010 s, followed by significant declines at rates of 1.8%–6.1% yr−1 to 2022. The GEM decline from 2013 to 2022 (by 38.6%±12.7%) coincides with the decreasing concentrations of criteria air pollutants in China, and is larger than those observed elsewhere in the Northern Hemisphere (5.7%–14.2%). The co-benefits of emission control measures contributed to the reduced anthropogenic Hg emissions and led to the GEM decline in China. We estimated that anthropogenic GEM emissions in China were reduced by 38%–50% (116–151 tons) from 2013 to 2022 using the machine learning and relationship models.

Identifying decadal trends in deweathered concentrations of criteria air pollutants in Canadian urban atmospheres with machine learning approaches

Abstract. This study investigates long-term trends of criteria air pollutants, including NO2, CO, SO2, O3 and PM2.5, and Ox (meaning NO2+O3) measured in 10 Canadian cities during the last 2 to 3 decades. We also investigated associated driving forces in terms of emission reductions, perturbations due to varying weather conditions and large-scale wildfires, as well as changes in O3 sources and sinks. Two machine learning methods, the random forest algorithm and boosted regression trees, were used to extract deweathered mixing ratios (or mass concentrations) of the pollutants. The Mann–Kendall trend test of the deweathered and original annual average concentrations of the pollutants showed that, on the timescale of 20 years or longer, perturbation due to varying weather conditions on the decadal trends of the pollutants are minimal (within ±2 %) in about 70 % of the studied cases, although it might be larger (but at most 16 %) in the remaining cases. NO2, CO and SO2 showed decreasing trends in the last 2 to 3 decades in all the cities except CO in Montréal. O3 showed increasing trends in all the cities except Halifax, mainly due to weakened titration reaction between O3 and NO. Ox, however, showed decreasing trends in all the cities except Victoria, because the increase in O3 is much less than the decrease in NO2. In three of the five eastern Canadian cities, emission reductions dominated the decreasing trends in PM2.5, but no significant trends in PM2.5 were observed in the other two cites. In the five western Canadian cities, increasing or no significant trends in PM2.5 were observed, likely due to unpredictable large-scale wildfires overwhelming or balancing the impacts of emission reductions on PM2.5. In addition, despite improving air quality during the last 2 decades in most cities, an air quality health index of above 10 (representing a very high risk condition) still occasionally occurred after 2010 in western Canadian cities because of the increased large-scale wildfires.

Decoupling impacts of weather conditions on interannual variations in concentrations of criteria air pollutants in South China – constraining analysis uncertainties by using multiple analysis tools

Abstract. In this study, three methods, i.e., the random forest (RF) algorithm, boosted regression trees (BRTs) and the improved complete ensemble empirical-mode decomposition with adaptive noise (ICEEMDAN), were adopted for investigating emission-driven interannual variations in concentrations of air pollutants including PM2.5, PM10, O3, NO2, CO, SO2 and NO2 + O3 monitored in six cities in South China from May 2014 to April 2021. The first two methods were used to calculate the deweathered hourly concentrations, and the third one was used to calculate decomposed hourly residuals. To constrain the uncertainties in the calculated deweathered or decomposed hourly values, a self-developed method was applied to calculate the range of the deweathered percentage changes (DePCs) of air pollutant concentrations on an annual scale (each year covers May to the next April). These four methods were combined together to generate emission-driven trends and percentage changes (PCs) during the 7-year period. Consistent trends between the RF-deweathered and BRT-deweathered concentrations and the ICEEMDAN-decomposed residuals of an air pollutant in a city were obtained in approximately 70 % of a total of 42 cases (for seven pollutants in six cities), but consistent PCs calculated from the three methods, defined as the standard deviation being smaller than 10 % of the corresponding mean absolute value, were obtained in only approximately 30 % of all the cases. The remaining cases with inconsistent trends and/or PCs indicated large uncertainties produced by one or more of the three methods. The calculated PCs from the deweathered concentrations and decomposed residuals were thus combined with the corresponding range of DePCs calculated from the self-developed method to gain the robust range of DePCs where applicable. Based on the robust range of DePCs, we identified significant decreasing trends in PM2.5 concentration from 2014 to 2020 in Guangzhou and Shenzhen, which were mainly caused by the reduced air pollutant emissions and to a much lesser extent by weather perturbations. A decreasing or probably decreasing emission-driven trend was identified in Haikou and Sanya with inconsistent PCs, and a stable or no trend was identified in Zhanjiang with positive PCs. For O3, a significant increasing trend from 2014 to 2020 was identified in Zhanjiang, Shenzhen, Guangzhou and Haikou. An increasing trend in NO2 + O3 was also identified in Zhanjiang and Guangzhou and an increasing or probably increasing trend in Haikou, suggesting the contributions from enhanced formation of O3. The calculated PCs from using different methods implied that the emission changes in O3 precursors and the associated atmospheric chemistry likely played a dominant role than did the perturbations from varying weather conditions. Results from this study also demonstrated the necessity of combining multiple decoupling methods in generating emission-driven trends in atmospheric pollutants.

Long-term trends and affecting factors in the concentrations of criteria air pollutants in South Korea

Here, we used a novel approach to analyze the trends in the concentrations of six national criteria air pollutants, carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), PM10, PM2.5, and surface ozone (O3), between 2001 and 2018, and the factors affecting the concentrations of CO and SO2 at the district level in South Korea (Korea) between 2011 and 2016. We considered four factors affecting the concentrations of CO and SO2: (1) concentration-to-emission ratio, (2) air pollutant-to-CO2 emission ratio, (3) carbon intensity, and (4) area-weighted energy supply. We found that the most influencing factors determining the concentrations of CO and SO2in Korea were the air pollutant-to-CO2emission ratio and the concentration-to-emission ratio. The annual mean concentrations of CO, SO2, PM10, PM2.5, and NO2 generally decreased, while O3 levels showed an increasing trend, over the last 18 years in Korea. We also found that NO2 concentration had strong positive and negative correlations with PM2.5 and O3 concentrations, respectively. However, the relationship between O3 and NO2 levels showed an inverted U shape under NO2 super-rich condition (e.g., > 55ppb in Seoul), and the daily maximum 8-h values (MDA8O3) increased in proportion to the NO2 level under poor NO2 conditions (e.g., < 25ppb in Seoul).

Impact of the ‘Coal-to-Natural Gas’ Policy on Criteria Air Pollutants in Northern China

During the last decades, China had issued a series of stringent control measures, resulting in a large decline in air pollutant concentrations. To quantify the net change in air pollutant concentrations driven by emissions, we developed an approach of determining the closed interval of the deweathered percentage change (DPC) in the concentration of air pollutants on an annual scale, as well as the closed intervals of cumulative DPC in a year compared with that in the base year. Thus, the hourly mean mass concentrations of criteria air pollutants to determine their interannual variations and the closed intervals of their DPCs during the heating seasons from 2013 to 2019 in Qingdao (a coastal megacity) were analyzed. The seasonal mean SO2 concentration decreased from 2013 to 2019. The seasonal mean CO, NO2, and PM2.5 concentrations also generally decreased from 2013 to 2017, but increased unexpectedly in 2018 (from 0.9 mg m−3 (CO), 42 µg m−3 (NO2), and 51 µg m−3 (PM2.5) in 2017 to 1.1 mg m−3, 48 µg m−3, and 64 µg m−3 in 2018, respectively). The closed intervals of DPC in concentrations of CO, NO2, and PM2.5 from the 2017 heating season (2017/2018) to the 2018 heating season (2018/2019) were obtained at (27%, 30%), (15%, 18%), and (30%, 33%), respectively. Such high positive endpoint values of the closed intervals, in contrast to their small interval lengths, indicate increased emissions of these pollutants and/or their precursors in 2018/2019 compared with 2017/2018, by minimizing the meteorological influences. The rebounds of CO, NO2, and PM2.5 in 2018/2019 were likely associated with a doubled increase in natural gas (NG) consumption implemented by the “coal-to-NG” project, as the total energy consumption showed little difference. Our results suggested an important role of the “coal-to-NG” project in driving concentrations of air pollutant increases in China in 2018/2019, which need integrated assessments.

Where Is Air Quality Improving, and Who Benefits? A Study of PM2.5 and Ozone Over 15 Years.

In the United States, concentrations of criteria air pollutants have declined in recent decades. Questions remain regarding whether improvements in air quality are equitably distributed across subpopulations. We assessed spatial variability and temporal trends in concentrations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5) and ozone (O3) across North Carolina from 2002-2016, and associations with community characteristics. Estimated daily PM2.5 and O3 concentrations at 2010 Census tracts were obtained from the Fused Air Quality Surface Using Downscaling archive and averaged to create tract-level annual PM2.5 and O3 estimates. We calculated tract-level measures of: racial isolation of non-Hispanic Black individuals, educational isolation of non-college educated individuals, the neighborhood deprivation index (NDI), and percentage of the population in urban areas. We fitted hierarchical Bayesian space-time models to estimate baseline concentrations of and time trends in PM2.5 and O3 for each tract, accounting for spatial between-tract correlation. Concentrations of PM2.5 and O3 declined by 6.4 μg/m3 and 13.5 ppb, respectively. Tracts with lower educational isolation and higher urbanicity had higher PM2.5 and more pronounced declines in PM2.5. Racial isolation was associated with higher PM2.5 but not with the rate of decline in PM2.5. Despite declines in pollutant concentrations, over time, disparities in exposure increased for racially and educationally isolated communities.

Particle Number Concentration: A Case Study for Air Quality Monitoring

Particle matter is one of the criteria air pollutants which have the most considerable effect on human health in cities. Its legislation and regulation are mostly based on mass. We showed here that the total number of particles and the particle number concentrations in different size fractions seem to be efficient quantities for air quality monitoring in urbanized areas. Particle number concentration (N) measurements were realized in Budapest, Hungary, for nine full measurements years between 2008 and 2021. The datasets were complemented by meteorological data and concentrations of criteria air pollutants. The annual medians of N were approximately 9 × 103 cm−3. Their time trends and diurnal variations were similar to other large continental European cities. The main sources of N are vehicle road traffic and atmospheric new aerosol particle formation (NPF) and consecutive growth events. The latter process is usually regional, so it appears to be better assessible for contribution quantification than mass concentration. It is demonstrated that the relative occurrence frequency of NPF was considerable, and its annual mean was around 20%. NPF events increased the contribution of ultrafine (UF &lt; 100 nm) particles with respect to the regional particle numbers by 12% and 37% in the city center and in the near-city background, respectively. The pre-existing UF concentrations were doubled on the NPF event days.

Decoupling Impacts of Weather Conditions on Interannual Variation in Concentrations of Criteria Air Pollutants in South China – Constraining Analysis Uncertainties by Using Multiple Analysis Tools

Decoupling Impacts of Weather Conditions on Interannual Variation in Concentrations of Criteria Air Pollutants in South China – Constraining Analysis Uncertainties by Using Multiple Analysis Tools

Air quality and public health risk assessment: A case study in a typical polluted city, North China

To evaluate air quality changes along with public health in Jinan, a typical polluted city of North China, spatial and temporal features of six criteria pollutants and relative health risk were conducted from 2013 to 2017. In general, the concentrations of criteria air pollutants except ozone had obviously decreased. For spatial pattern, the air qualities in north Jinan were influenced by dust, vehicle and industry emission. Health risk evaluation showed people mainly suffered health risk from PM10 and PM2.5. However, O3 had become another noticeable pollutant in recent years. Compared with other cities in China, the citizens in Jinan were more likely to suffer from much higher health risk categories than the current Air Quality Index (AQI) approach, particularly in winter. During severe polluted episodes, secondary formation via heterogeneous reaction would increase public health risk from air pollution. Back trajectories and potential source contribution function (PSCF) analysis identified anthropogenic sources from near provinces particularly to the east and south may aggravate air pollution by air mass transport. In general, the emission controls on VOCs, NO2 and regional joint pollution prevention would be essential to reduce urban air pollution in the next phases.

Assessment of air quality within Maiganga coal mining area in Akko Local Government Area, Gombe State, Nigeria

Anthropogenic activity especially coal mining contributes immensely to environmental pollution within coalmine and the host community especially if not well managed. This study is on the assessment of air quality in and around Maiganga coalmine, with the objectives of finding out the ambient concentration levels of criteria air pollutants within the coalmine, the Maiganga community and the four control sites 2km north, south, east and west of the coalmine, as well as compare the findings with the concentration levels of pollutants recommended as acceptable safety limits set by Federal Ministry of Environment, FMEnv. Six sampling locations were selected for detail assessment, with one point in each of the sites mentioned. Measurement of concentrations of criteria air pollutants; sulphur dioxide (SO2), nitrogen dioxide (NO2) volatile organic compounds (VOCs), carbon monoxide (CO), ammonia (NH3), and ozone (O3) were taken in-situ using Personal Toxic Gas Monitor (Tango TXI single gas monitor). Fine particulate matter (PM2.5), coarse particulate matter (PM10), were collected using a Portable Counter HT – 9601 (PM2.5 and PM10) personal dust meter high volume gravity sampler. Volatile organic compounds (VOCs) were also measured using a Portable Hand Held Gas Detector (Porcheck+). The study was done during the dry season and the results revealed that, coarse paticulate matter (PM10) was above the stipulated safety limit of 250µg/m3 set by the FMEnv for the coal mine area and Maiganga community but all other parameters were within the safety limits of the FMEnv. CO, NO2, SO2, and NH3 in coalmine area had concentrations lower than in that in control areas because of other anthropogenic activities like burning, heating, waste disposal, agricultural practices and a host of others taking place in the control area and which are not available in the coalmine area. However, the concentrations of the aforementioned parameters were higher in Maiganga community than in the control areas due to higher rate of anthropogenic activities in the community than in the control areas. The hypothesis were tested using student t – test, and the alternative hypothesis was accepted which showed there was no significant variations in the values of fine particulate matter (PM2.5), coarse particulate matter (PM10), sulphur dioxide (SO2), nitrogen dioxide (NO2), volatile organic compounds (VOCs), carbon monoxide (CO), ammonia (NH3), and ozone (O3) obtain from the coalmine, Maiganga community and the Control (N.S.E.W) with safety limits set by FMEnv. It is however, recommended that the Federal Ministry of Environment and National Environmental Standards and Regulations Enforcement Agency (NESREA) should ensure strict compliance with safety and environmental standards agreed upon during Environmental Impact Assessment (EIA).

Effects of the COVID-19 lockdown on criteria air pollutants in the city of Daegu, the epicenter of South Korea's outbreak.

The outbreak of COVID-19 in Daegu, South Korea, early in 2020 has led this metropolitan city to become one of the major hotspots in the world. This study investigates the association of meteorology and the new daily COVID-19 confirmed cases and the effects of the city lockdown on the variation in criteria air pollutants (CAPs) in Daegu. Ambient temperature and relative humidity were negatively correlated to the new daily cases and played an important role in the spread of COVID-19. Wind speed could enhance the virus transmission through the inhalation of aerosols and/or droplets and contact with fomites. The lockdown has directly decreased the concentrations of CAPs. In particular, reductions of 3.75% (PM10), 30.9% (PM2.5), 36.7% (NO2), 43.7% (CO), and 21.3% (SO2) between the period before and during the outbreak were observed over the entire city. An increase in O3 (71.1%) was affected by natural processes and photochemical formation other than the lockdown effects. The three central districts were the areas most affected by the virus and showed the highest reductions in CAPs (except for O3) during the outbreak. Apart from the influence of the lockdown, the decreasing trend in CAPs may be a result of the actions taken by the government to mitigate air pollutants nationwide since 2019. The results of this study can be useful for government and medical organizations to understand the behavior of the virus in the atmosphere. Further studies are necessary to explore the detailed influences of the lockdown on the environment and public life.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-020-11360-4.

Short-term effects of anthropogenic/natural activities on the Tehran criteria air pollutants: Source apportionment and spatiotemporal variation

In this paper, we apply a somewhat new approach to address the data missing issue of the detailed air monitoring dataset of Tehran 2018 (hourly data of over 15 monitoring sites) and to study the short-term effects of anthropogenic/natural activities on the criteria air pollutants (CAP) in the urban and rural areas. A homogenous dataset was produced by the Singular Value Thresholding (SVT) algorithm and source apportionment was then conducted using the absolute principle component scores-multiple linear regression (APCS-MLR) method. The contributions of major sources to the local ozone level and the existing correlations between the CAP concentrations are also discussed. Results show that the vehicular emissions were the predominant contributors to the CAP concentrations, accounting for an average of 45%, and desert dust and industries around the city were ranked as the subsequent principal CAP sources for the summer season. Residential and transportation sectors accounted for an average of 59% and 18.4% of the CAP concentrations in the wintertime, respectively. Aerosols formation was accelerated during the “lunch-time” peak. This phenomenon was attributed to the heavy traffic emission of Tehran in urban environments. The concentrations of CAP, except ozone, gently increase by moving toward the cold days of the year, whereas O3 concentration usually exceeds 70 μg/m3 in summer days. On-road vehicle emissions were the leading source of ozone formation in Tehran for the studied time. The correlation coefficients of ozone and other CAP vary to some extent by moving from urban areas toward the rural areas of the city.

충청남도 지역 2018년 초여름 대기환경기준물질 농도의 시간적·공간적 변화 분석

충청남도 지역 2018년 초여름 대기환경기준물질 농도의 시간적·공간적 변화 분석

Effects of meteorological variables and holidays on the concentrations of PM10, PM2.5, O3, NO2, SO2, and CO in Tehran (2014-2018)

Introduction: The aim of this study was to investigate the concentrations&#x0D; &#x0D; of PM10, PM2.5, O3, NO2, SO2, and CO in Tehran during March 2014-March 2018, and evaluate the effects of holidays and meteorological parameters on&#x0D; &#x0D; the air pollution levels.&#x0D; &#x0D; Materials and methods: Hourly concentrations of PM10, PM2.5, O3, NO2, SO2, and CO in different air quality monitors of Tehran were acquired. The data from each air quality monitored were validated, and only high-quality monitors were included in this study.&#x0D; &#x0D; Results: The 4-year averages of PM10, PM2.5, O3, NO2, SO2, and CO concen-trations were 88.74 (µg/m3), 31.02 (µg/m3), 34.87 (ppb), 71.01 (ppb), 20.04&#x0D; &#x0D; (ppb), and 3.78 (ppm), respectively. Higher concentrations of PM10 and O3 were observed during summer. In case of PM2.5 and CO, autumn and winter concentrations were higher than those in springer and summer. Lower concen-trations of PM10 and NO2 in Fridays were observed comparing to other days of week. Ozone had high concentrations in Fridays as the weekend in Iran. Except for O3, all of the pollutants had higher concentrations in the working days, comparing to those in any type of vacation days. Concentrations of all pollutants rather that SO2 and O3 in Nowruz holidays were statistically lower than those in the working days. By controlling for the effects of meteorologi-cal variables, our results showed that the air pollution control policies and ac-tions have been not effective for particulate matter.&#x0D; &#x0D; Conclusion: These results determines the time periods in which the concen-trations of criteria air pollutants are high. This can be very useful for an-nouncing alarms for citizens, and designing the air pollution control plans. In addition, more effective actions should be designed and implemented for reducing ambient levels of particulate matter.

Investigating horizontal and vertical pollution gradients in the atmosphere associated with an urban location in complex terrain, Reno, Nevada, USA

A new statistical method, the quadrant method, was used to aid in identifying different conditions affecting the relationship between columnar aerosol optical depth (τext) and surface concentrations of particulate matter (<2.5 μg m−3 in aerodynamic diameter, PM2.5). The main goal of this study was to identify air pollution sources and atmospheric processes affecting gradients of atmospheric pollutants observed at two valley sites (∼1370 m) and a high elevation site (2515 m) located in and adjacent to Reno, Nevada, USA. The two valley sites were used to investigate the horizontal gradient of pollutants associated with mobile sources from high volume highways. Results indicated statistically significant differences in concentrations of criteria air pollutants between the two valley sites, located 0.03 km and >1 km from major highways. Vertical gradients were impacted by air pollution sources, including local and long-range transport, and atmospheric boundary layer stability. During periods when τext and surface PM2.5 concentrations were associated (i.e. both increase), emissions from wildfires and local pollutants in a well-mixed boundary layer dominated the relationship. During periods of no association, stable boundary layer conditions and pollution aloft created vertical heterogeneity of PM2.5 concentrations. Results showed that the quadrant method, developed for hourly data, can be used with 24 h PM2.5 and gaseous data and that it is a useful tool for identifying air pollution sources and atmospheric physics driving pollution gradients.

Assessment on pattern of urban air quality by using chemometric technique:a case study in Kota Kinabalu, Sabah

The study evaluate the relationship between the main daily concentrations of criteria air pollutants in urban areas and their associations by using chemometric technique. Data were gathered from the Department of Environmental for three years observations (2011-2013) consisting of 5 major pollutants such as SO 2 , NO 2 , O 3 ,CO and PM 10 and meteorological parameters such as wind direction, wind speed, temperature and humidity were used. Chemometric technique such asPCA and SPC were used in this study.It can be concluded that Chemometric technique is meaningful tool for assessment of large and complex air quality data. Besides, it also able to give a clear picture about trends, pattern of major air pollutants and sources identification of pollutants in the study area. This is important for a better management of air quality in the future which able to reduce the possible health and environmental effect.

Characterization of air quality and sources of fine particulate matter (PM2.5) in the City of Calgary, Canada

With concern about fine particulate matter (PM2.5) pollution in urban areas and levels approaching a new Canadian Ambient Air Quality Standards (CAAQS), an exploratory study of air quality characteristics and potential sources affecting PM2.5 levels was undertaken in the City of Calgary, Alberta. The study was performed for the economic recession period 2014 to 2016 using hourly concentrations of criteria air pollutants at two monitoring stations (Calgary central and Calgary northwest). The overall mean and median PM2.5 concentrations were similar at both Calgary central (arithmetic mean: 7.7 μg/m3, median: 6.0 μg/m3) and Calgary northwest (arithmetic mean: 7.5 μg/m3, median: 6.0 μg/m3). Three-year averages of annual average daily 24 h PM2.5 concentrations at both stations were below the 2015 annual CAAQS of 10 μg/m3 during the study period 2014–2016. A multivariate receptor model positive matrix factorization (PMF) revealed five sources, where secondary aerosol was identified as the largest source of PM2.5 contributing 54% at Calgary central and 42% at Calgary northwest. Other sources included combustion (18%, 39%), traffic (18%, 12%), an O3-rich source (8%, 4%), and a mixed urban source (2%, 3%) at Calgary central and Calgary northwest, respectively. Variations in annual contributions of secondary aerosol, combustion and traffic were observed at Calgary downtown for 2014–2016. At Calgary northwest no variation was found for annual traffic contributions. These findings offer preliminary information about the contributions of different potential sources to PM2.5 in Calgary; and this information can support policy makers in developing appropriate air quality management initiatives for PM2.5 pollution if needed.

Characterization of air quality and fine particulate matter sources in the town of Hinton, Alberta

With concern in recent years about dust issues and fine particulate matter (PM2.5) levels approaching a new Canadian Ambient Air Quality Standards (CAAQS), an investigation of air quality characteristics and potential sources influencing PM2.5 concentrations was undertaken in the community of Hinton, Alberta. The study was conducted for the period November 2013 to February 2016 using hourly concentrations of criteria air pollutants. Comparatively higher concentrations of PM2.5 were observed in summer (mean: 12.5 μg/m3, median: 8.0 μg/m3) than in winter (mean: 7.5 μg/m3, median: 6.0 μg/m3).The 3-year averages of annual average PM2.5 concentrations (8.1–8.9 μg/m3) were below the 2015 annual CAAQS value of 10 μg/m3. Exceedances of a 1 h Alberta Ambient Air Quality objective (58 times > 80 μg/m3) and a 24 h CAAQS (16 times > 28 μg/m3) were observed at Hinton for the study period and occurred during summer months primarily due to occurrence of forest fire episodes. A multivariate model positive matrix factorization (PMF) revealed five sources. Background dust and secondary aerosol was identified as the largest source contributing 68% to PM2.5 mass. Other sources included traffic (13.4%), an O3-rich source (12.7%), industry (3.1%) and a mixed source (3.1%). These findings offer preliminary information about contributions of different sources to PM2.5 at Hinton; and this information can support policy makers in developing appropriate management initiatives for reducing dust and secondary particulate matter pollution.

Exposure to low ambient concentrations of criteria air pollutants in Ontario, Canada, and the incidence of acute myocardial infraction and congestive heart failure, 1996-2012

Exposure to low ambient concentrations of criteria air pollutants in Ontario, Canada, and the incidence of acute myocardial infraction and congestive heart failure, 1996-2012

Seasonal and Temporal Variations of Criteria Air Pollutants and the Influence of Meteorological Parameters on the Concentration of Pollutants in Ambient Air in Lahore, Pakistan

Criteria air pollutants have their significance for causing health threats and damage to theenvironment. The study was conducted to assess the seasonal and temporal variations of criteria air pollutantsand evaluating the correlations of criteria air pollutants with meteorological parameters in the city ofLahore, Pakistan for a period of one year from April 2010 to March 2011. The concentrations of criteriaair pollutants were determined at fixed monitoring stations equipped with HORIBA analyzers. The annualaverage concentrations (µg/m3) of PM2.5, O3, SO2, CO and NOx (NO+NO2) for this study period were118.94±57.46, 46.0±24.2, 39.9±8.9, 1940±1300 and 130.9±81.0 (61.8±46.2+57.3±22.19), respectively.PM2.5, SO2, CO and NOx had maximum concentrations during winter whereas O3 had maximum concentrationduring summer. Minimum concentrations of PM2.5, SO2 and NOx were found during monsoon as comparedto other seasons due to rainfall which scavenged these pollutants. The O3 showed positive correlation withtemperature and solar radiation but negative correlation with wind speed. All other criteria air pollutantsshowed negative correlation with wind speed, temperature and solar radiation. A significant (P&lt;0.01)correlation was found between NOx and CO (r = 0.779) which showed that NOx and CO arise from commonsource that could be the vehicular emission. PM2.5 was significantly correlated (P&lt;0.01) with NOx (r = 0.524)and CO (r = 0.519), respectively. High traffic intensity and traffic jams were responsible for increased airpollutants level especially the PM2.5, NOx and CO.