Air pollution we breathe: Assessing the air quality and human health impact in a megacity of Southeast Asia.

With 24 million inhabitants and 6.6 million vehicles on the roads, Karachi, Pakistan ranks among the world's most polluted cities due to high levels of fine particulate matter (PM2.5). This study aims to investigate PM2.5 mass, seasonal and temporal variability, chemical characterization, source apportionment, and health risk assessment at two urban sites in Karachi. Samples were analyzed using ion chromatography and dual-wavelength optical transmissometer for various inorganic components (anions, cations, and trace elements) and black carbon (BC). Several PM2.5 pollution episodes were frequently observed, with annual mean concentrations at Kemari (140 ± 179 µg/m3) and Malir (95 ± 40.9 µg/m3) being significantly above the World Health Organization's guidelines of 5 µg/m3. Chemical composition at both sites exhibited seasonal variability, with higher pollution levels in winter and fall and lower concentrations in summer. The annual average BC concentrations were 4.86 ± 5.29 µg/m3 and 4.52 ± 3.68 µg/m3, respectively. A Positive Matrix Factorization (PMF) analysis identified 5 factors, crustal, sea salt, vehicular exhaust, fossil-fuel combustion, and industrial emission. The health risk assessment indicated a higher number of deaths in colder seasons (fall and winter) at the Kemari (328,794 and 287,814) and Malir (228,406 and 165,737) sites and potential non-carcinogenic and carcinogenic risks to children from metals. The non-carcinogenic risk of PM2.5 bound Pb, Fe, Zn, Mn, Cr, Cu and Ni via inhalation exposure were within the acceptable level (<1) for adults. However, potential non-carcinogenic and carcinogenic health risk posed by Pb and Cr through inhalation were observed for children. The findings exhibit critical levels of air pollution that exceed the safe limits in Karachi, posing significant health risks to children and sensitive groups. Our study underscores the urgent need for effective emission control strategies and policy interventions to mitigate these air pollution risks.

Beyond the outdoors: indoor air quality guidelines and standards - challenges, inequalities, and the path forward.

In the last few decades, indoor air quality (IAQ) has become a major threat to public health. It is the fifth leading cause of premature death globally. It has been estimated that people spend ∼90 % of their time in an indoor environment. Consequently, IAQ has significant health effects. Although IAQ-related standards and guidelines, policies, and monitoring plans have been developed in a few countries, there remain several global inequalities and challenges. This review paper aims to comprehensively synthesize the current status of widely accepted IAQ guidelines and standards. It analyzes their global implementation and effectiveness to offer insights into challenges and disparities in IAQ policies and practices. However, the complexity of domestic environments and the diversity of international standards impede effective implementation. This manuscript evaluates international, national, and regional IAQ guidelines, emphasizing similarities and differences. In addition, it highlights knowledge gaps and challenges, urging the international scientific community, policymakers, and stakeholders to collaborate to advance IAQ standards and guidelines. The analysis evaluates the efficacy of guidelines, identifies deficiencies, and offers recommendations for the future of domestic air quality standards.

Fine particulate matter and its chemical constituents' levels: A troubling environmental and human health situation in Karachi, Pakistan.

Like many urban centers in developing countries, the effect of air pollution in Karachi is understudied. The goal of this study was to determine the chemical characterization, temporal and seasonal variability, sources, and health impacts of fine particulate matter (PM2.5) in Karachi, Pakistan. Daily samples of PM2.5 were collected using a low-volume air sampler at two different sites (Makro and Karachi University) over the four seasons between October 2009 and August 2010. Samples were analyzed for black carbon (BC), trace metals, and water-soluble ions. Results showed that the annual average concentrations of PM2.5 at Makro and Karachi University were 114 ± 115 and 71.7 ± 56.4 µg m-3, respectively, about 22.8 and 14.3-fold higher than the World Health Organization annual guideline of 5 µg m-3. BC concentrations were 3.39 ± 1.97 and 2.70 ± 2.06 µg m-3, respectively. The concentrations of PM2.5, BC, trace metals, and ions at the two sites showed clear seasonal trends, with higher concentrations in winter and lower concentrations in summer. The trace metals and ionic species with the highest concentrations were Pb, S, Zn, Ca, Si, Cl, Fe, and SO42-. The air quality index in the fall and winter at both sites was about 68 %, which is "unhealthy" for the general population. Positive Matrix Factorization revealed the overall contribution to PM2.5 at the Makro site came from three major sources - industrial emissions (13.3 %), vehicular emissions (59.1 %), and oil combustion (23.3 %). The estimates of expected number of deaths due to short-term exposure to PM2.5 were high in the fall and winter at both sites, with an annual mean estimate of 3592 expected number of deaths at the Makro site. Attention should be paid to the reduction of inorganic pollutants from industrial facilities, vehicular traffic, and fossil fuel combustion, due to their extremely high contribution to PM2.5 mass and health risks.

State of gaseous air pollutants and resulting health effects in Karachi, Pakistan.

Karachi, Pakistan, is a priority site for air pollution research due to high emissions of air pollutants from vehicular traffic, industrial activities, and biomass burning, as well as rapid growth in population. The objectives of this study were to investigate the levels of gaseous pollutants (NO, NO2, O3, HNO3, and SO2) in Karachi, to determine temporal and seasonal variations, to compare Karachi's air quality with other urban centers, to identify relationships with meteorological conditions, to identify source characterization, and to perform a backward-in-time trajectory analysis and a health impact assessment. Daily samples of gaseous pollutants were collected for six consecutive weeks in each of the four seasons for a year. Daily maximum concentrations of NO (90 parts per billion by volume (ppbv)), NO2 (28.1 ppbv), O3 (57.8 ppbv), and SO2 (331 ppbv) were recorded in fall, while HNO3 (9129 parts per trillion by volume (pptv)) was recorded in spring. Seasonal average concentrations were high in winter for NO (9.47 ± 7.82 ppbv), NO2 (4.84 ± 3.35 ppbv), and O3 (8.92 ± 7.65 ppbv), while HNO3 (629 ± 1316 pptv) and SO2 (20.2 ± 39.4 ppbv) were high in spring and fall, respectively. The observed SO2 seasonal average concentration in fall (20.2 ± 39.4) was 5 times higher than that in summer (3.97 ± 2.77) with the fall 24-h average (120 ppbv) exceeding the WHO daily guideline (7.64 ppbv) by a factor of about 15.7. A health impact assessment estimated an increase of 1200 and 569 deaths due to short-term exposure to SO2 in fall and spring, respectively. Chronic daily intake estimated risk per 1000 was 0.99, 0.47, 0.45, and 0.26 for SO2 in fall, NO in winter, O3 in winter, and NO2 in spring, respectively. This study confirms the effect of poor urban air quality on public health and demonstrated the influence of photochemical reactions as well as unfavorable meteorological conditions on the formation of secondary pollutants.

Residential Proximity to Biorefinery Sources of Air Pollution and Respiratory Diseases in New York State.

Understanding potential health risks associated with biofuel production is critical to sustainably combating energy insecurity and climate change. However, the specific health impacts associated with biorefinery-related emissions are not yet well characterized. We evaluated the relationship between respiratory emergency department (ED) visits (2011-2015) and residential exposure to biorefineries by comparing 15 biorefinery sites to 15 control areas across New York (NY) State. We further examined these associations by biorefinery types (e.g., corn, wood, or soybean), seasons, and lower respiratory disease subtypes. We measured biorefinery exposure using residential proximity in a cross-sectional study and estimation of biorefinery emission via AERMOD-simulated modeling. After controlling for multiple confounders, we consistently found that respiratory ED visit rates among residents living within 10 km of biorefineries were significantly higher (rate ratios (RRs) range from 1.03 to 3.64) than those in control areas across our two types of exposure indices. This relationship held across biorefinery types (higher in corn and soybean biorefineries), seasons (higher in spring and winter), air pollutant types (highest for NO2), and respiratory subtypes (highest for emphysema). Further research is needed to confirm our findings.

Identifying and evaluating school environmental health indicators.

Children's health, attendance, and academic performance may be affected by school environmental hazards. While prior studies evaluated home environment and health, few have evaluated indicators of school in-/outdoor environment and health. This study addresses this knowledge gap by systematically reviewing and evaluating outdoor and indoor indicators of school environment and student's health and performance in New York State (NYS). We also evaluate statistical methodologies to address highly correlated indicators and integrate multiple exposures. Multiple school environmental indicators were identified from various existing NYS datasets. We summarized data sources, completeness, geographic and temporal coverage, and data quality for each indicator. Each indicator was evaluated by scientific basis/relevance, analytic soundness/feasibility, and interpretation/utility, and validated using objective NYS data. Finally, advanced variable selection methods were described and discussed. We have identified and evaluated multiple school environmental health indicators. It was found that mold and moisture problems, ventilation problems, ambient ozone, and PM2.5 levels are among the top priorities of school environmental issues/indicators in NYS, which were also consistent while using NYS data. Choice of best variable selection method should be made based on the research questions and data characteristics. The school environmental health indicators identified, and variable selection methods evaluated, in this study could be used by other researchers to help school officials and policy makers initiate prevention programs.

Projecting life-cycle environmental impacts of corn production in the U.S. Midwest under future climate scenarios using a machine learning approach.

Climate change is exacerbating environmental pollution from crop production. Spatially and temporally explicit estimates of life-cycle environmental impacts are therefore needed for suggesting location and time relevant environmental mitigations strategies. Emission factors and process-based mechanism models are popular approaches used to estimate life-cycle environmental impacts. However, emission factors are often incapable of describing spatial and temporal heterogeneity of agricultural emissions, whereas process-based mechanistic models, capable of capturing the heterogeneity, tend to be very complicated and time-consuming. Efficient prediction of life-cycle environmental impacts from agricultural production is lacking. This study develops a rapid predictive model to quantify life-cycle global warming (GW) and eutrophication (EU) impacts of corn production using a novel machine learning approach. We used the boosted regression tree (BRT) model to estimate future life-cycle environmental impacts of corn production in U.S. Midwest counties under four emissions scenarios for years 2022-2100. Results from BRT models indicate that the cross-validation (R2) for predicting life cycle GW and EU impacts ranged from 0.78 to 0.82, respectively. Furthermore, results show that future life-cycle GW and EU impacts of corn production will increase in magnitude under all four emissions scenarios, with the highest environmental impacts shown under the high-emissions scenario. Moreover, this study found that changes in precipitation and temperature played a significant role in influencing the spatial heterogeneity in all life-cycle impacts across Midwest counties. The BRT model results indicate that machine learning can be a useful tool for predicting spatially and temporally explicit future life-cycle environmental impacts associated with corn production under different climate scenarios.

Assessing the association between fine particulate matter (PM2.5) constituents and cardiovascular diseases in a mega-city of Pakistan.

Concerning PM2.5 concentrations, rapid industrialization, along with increase in cardiovascular disease (CVD) were recorded in Pakistan, especially in urban areas. The degree to which air pollution contributes to the increase in the burden of CVD in Pakistan has not been assessed due to lack of data. This study aims to describe the characteristics of PM2.5 constituents and investigate the impact of individual PM2.5 constituent on cardiovascular morbidity in Karachi, a mega city in Pakistan. Daily levels of twenty-one constituents of PM2.5 were analyzed using samples collected at two sites from fall 2008 to summer 2009 in Karachi. Hospital admission and emergency room visits due to CVD were collected from two large hospitals. Negative Binominal Regression was used to estimate associations between pollutants and the risk of CVD. All PM2.5 constituents were assessed in single-pollutant models and selected constituents were assessed in multi-pollutant models adjusting for PM2.5 mass and gaseous pollutants. The most common CVD subtypes among our participants were ischemic heart disease, hypertension, heart failure, and cardiomyopathy. Extremely high levels of PM2.5 constituents from fossil-fuels combustion and industrial emissions were observed, with notable peaks in winter. The most consistent associations were found between exposure to nickel (5-14% increase per interquartile range) and cardiovascular hospital admissions. Suggestive evidence was also observed for associations between cardiovascular hospital admissions and Al, Fe, Ti, and nitrate. Our findings suggested that PM2.5 generated from fossil-fuels combustion and road dust resuspension were associated with the increased risk of CVD in Pakistan.

Fine particles exposure and cardiopulmonary morbidity in Jeddah: A time-series analysis.

Health effects linked to PM2.5, have been extensively studied in developed countries of Europe and N. America. However, little has been done in Saudi Arabia and the Middle East. This study evaluated the morbidity risk for cardiovascular (CVD) and respiratory (RD) diseases, associated with PM2.5 exposure in Jeddah, Saudi Arabia. 24-h PM2.5 sampling was conducted at 3 sites for 6 weeks quarterly from Apr 8th, 2013-Feb 18th, 2014 with simultaneous hospital data collection. The relative risks (RRs) for cardiopulmonary morbidity at different moving averages (MAs) of lagged exposures were estimated using a generalized linear time-series model. Elevated risks for RD were associated with recent PM2.5 exposures (0-2 days). RD prevalence was highest in children 0-14 years. Overall, RD morbidity risk ranged from 1.081 (CI: 1.005-1.162) to 1.096 (CI: 1.023-1.173) at MAs_2-4; male, 1.081 (CI: 1.019-1.146) to 1.087 (CI: 1.020-1.159) at MAs_2-3, and female, 1.086 (CI: 1.007-1.172) to 1.093 (CI: 1.017-1.175) at MAs_2-4. Generally, females 0-14 years were the most at risk for RDs with RR = 1.097 (CI: 1.025-1.174) to 1.148 (CI: 1.049-1.257). CVD morbidity risk was highest in ER visits with overall RR = 1.057 (CI: 1.005-1.111) to 1.137 (CI: 1.065-1.213) across all MAs; male, 1.060 (CI: 1.007-1.204) to 1.131 (CI: 1.060-1.208); female, 1.065 (CI: 1.008-1.125) to 1.116 (CI: 1.045-1.192). PM2.5 exposure showed significantly increased cardiopulmonary morbidity risk, accentuating the severe health effects associated with elevated PM2.5 in Jeddah. Overall, females (0-14 years) were more at risk for RD morbidity than males. CVD morbidity risk was relatively higher in males than females, with highest risk observed in age-groups above 40 years.

Ambient air quality in the holy city of Makkah: A source apportionment with elemental enrichment factors (EFs) and factor analysis (PMF).

Air pollution remains a major global public health and environmental issue. We assessed the levels of PM2.5 and delineated the major sources in Makkah, Saudi Arabia. Fine particulate matter (PM2.5) sampling was performed from February 26, 2014-January 27, 2015 in four cycles/seasons. Samples were analyzed for black carbon (BC) and trace elements (TEs). PM2.5 source apportionment was performed by computing enrichment factors (EFs) and positive matrix factorization (PMF). Backward-in time trajectories were used to assess the long-range transport. Significant seasonal variations in PM2.5 were observed, Spring: 113 ±â€¯67.1, Summer: 88.3 ±â€¯36.4, Fall: 67.8 ±â€¯24, and Winter: 67.6 ±â€¯36.9 µg m-3. The 24-h PM2.5 exceeded the WHO (25 µg m-3) and Saudi Arabia's (35 µg m-3) guidelines, with an air quality index (AQI) of "unhealthy to hazardous" to human health. Most delta-C computations were below zero, indicating minor contributions from bio-mass burning. TEs were primarily Si, Ca, Fe, Al, S, K and Mg, suggesting major contributions from soil (Si, Ca, Fe, Al, Mg), and industrial and vehicular emissions (S, Ca, Al, Fe, K). EF defined two broad categories of TEs as: anthropogenic (Cu, Zn, Eu, Cl, Pb, S, Br and Lu), and earth-crust derived (Al, Si, Na, Mg, Rb, K, Zr, Ti, Fe, Mn, Sr, Y, Cr, Ga, Ca, Ni and Ce). Notably, all the anthropogenic TEs can be linked to industrial and vehicular emissions. PMF analysis defined four major sources as: vehicular emissions, 30.1%; industrial-mixed dust, 28.9%; soil/earth-crust, 24.7%; and fossil-fuels/oil combustion, 16.3%. Plots of wind trajectories indicated wind direction and regional transport as major influences on air pollution levels in Makkah. In collusion, anthropogenic emissions contributed >75% of the observed air pollution in Makkah. Developing strategies for reducing anthropogenic emissions are paramount to controlling particulate air pollution in this region.

Association of fine particulate air pollution with cardiopulmonary morbidity in Western Coast of Saudi Arabia.

OBJECTIVES: To assess cardiopulmonary morbidity associated with daily exposures to PM2.5 in Western Coast of Saudi Arabia. Methods: We monitored 24-h PM2.5 and its constituents including black carbon (BC), particulate sulfate (p-SO42-), nitrate (p-NO3-), ammonium (p-NH4+) and trace elements (TEs) at a site in Rabigh, Saudi Arabia from May to June 2013 with simultaneous collection of hospital data (N=2513). Cardiopulmonary morbidity risk was determined in a generalized linear time-series model.  Results: Exposure to PM2.5 was associated with a 7.6% (p=0.056) increase in risk of respiratory disease (RD) in females. Black carbon increased RD morbidity risk by 68.1% (p=0.056) in females. Exposure to p-SO42- increased the cardiovascular disease (CVD) risk by up to 5.3% (p=0.048) in males; and RD by 2.9% (p=0.037) in females and 2.5% (p=0.022) in males. The p-NH4+ increased CVD risk by up to 20.3% (p=0.033) in males; and RD by 10.7% (p=0.014) in females and 8% (p=0.031) in males. No statistically significant association was observed for p-NO3- and TEs exposure. Conclusion: Overall, results show an increased risk for cardiopulmonary morbidity following exposure to air pollution.

Multipathways human health risk assessment of trihalomethane exposure through drinking water.

Life-time human health risk of cancer attributed to trihalomethanes in drinking water in an urban-industrialized area of Karachi (Pakistan) was conducted through multiple pathways of exposure. The extent of cancer risk was compared with USEPA guidelines. Human health cancer risk for total trihalomethanes (TTHMs) through ingestion and dermal routes were estimated in "acceptable-low risk" (≥1.0E-06; ≤5.10E-05), whereas through inhalation route it was estimated under "acceptable-high risk" (≥5.10E-05; ≤1.0E-04) category. However, at some industrial-urban areas cancer risk for CHCl3 were estimated under "unacceptable risk" (≥1.0E-04) through inhalation route.

Carbonyls and non-methane hydrocarbons at a rural mountain site in northeastern United States.

Measurements of carbonyls and C(2)-C(6) non-methane hydrocarbons (NMHCs) were made in ambient air at a rural site at the summit of Whiteface Mountain (WFM) in New York State. Alkanes dominated in the samples, with ethane and propane making up about 55% of the total on a carbon-atom basis. Ethane, the longest-lived of the NMHCs, showed a mixing ratio in the range of 0.86-2.1 ppbv. Photochemical ageing analysis indicated an anthropogenic influence on the NMHC levels. The photochemical reactivity of the hydrocarbons, calculated in terms of propylene-equivalent concentration, was dominated by alkenes (propene and ethene), which accounted for 74% of the total NMHC sum. Air mass back-trajectories have been used to investigate the origin of the observed NMHCs and carbonyls. Higher concentrations were found when air masses arrived from the midwestern US corridor. Acetone was the most abundant species, comprising from 31% to 53% of the total detected carbonyls, followed by MEK (15-53%), HCHO (7-39%), and CH(3)CHO (7-19%). Average concentrations were determined to be 1.61 ppbv for CH(3)C(O)CH(3), 1.40 ppbv for MEK, 1.16 ppbv for HCHO, and 0.49 ppbv for CH(3)CHO. The variations in carbonyl concentrations were observed to follow patterns similar to variations in O(3) concentrations, typical of secondary products. Correlations and statistical analysis of the carbonyls and NMHCs were performed, and showed that most of the compounds derived from mixing and photochemical transformation of long-range transported pollutants from the major source areas. Ranking of the carbonyls with respect to removal of the OH radical showed HCHO to be the most important species, followed by CH(3)CHO, MEK, and CH(3)C(O)CH(3).

Lead content of petrol and diesel and its assessment in an urban environment.

Pakistan is one of the few countries in Asia that continues to use only leaded-petrol as vehicular fuel. The concentration of Pb in its petrol reported in 1991 was the highest (1.5-2.0 g Pb L(-1)) of all produced by the various Asian countries and far exceeded the WHO's guideline of 0.15 g Pb L(-1). We have undertaken a study to trace and quantify this toxic element in the environs of Karachi. Pakistan's major metropolis, having more than 30% of the nation's total number of vehicles. In this article we report the Pb contents of petrol and diesel currently manufactured and marketed in the city. Samples of 'Regular' petrol collected in 1999 was found to contain 0.363 g Pb L(-1) (range: 0.335-0.390 g Pb L(-1)), a factor of 5 lower than that marketed prior to 1991. Its concentration in diesel fuel was much lower (0.017 g Pb L(-1)). Based on the available statistical data on the type and volume of vehicular traffic, we assessed that the current lead emission from vehicular traffic into the atmosphere is 391 metric tons a year, which is a factor of 2.7 lower than that estimated for 1989.