Sudhir Kumar Pandey

The modern paradox of unregulated cooking activities and indoor air quality

Pollutant emission from domestic and commercial cooking activities is a previously neglected area of concern with respect to human health worldwide. Its health effects are relevant to people across the globe, not only those using low quality food materials in lesser-developed countries but also to more affluent people enjoying higher quality food in developed countries. Based on the available database of pollutant emissions derived from fire-based cooking, its environmental significance is explored in a number of ways, especially with respect to the exposure to hazardous vapors and particulate pollutants. Discussion is extended to describe the risk in relation to cooking methods, cooking materials, fuels, etc. The observed pollutant levels are also evaluated against the current regulations and guidelines established in national and international legislation. The limitations and future prospects for the control of cooking hazards are discussed.

The Relative Performance of NDIR-based Sensors in the Near Real-time Analysis of CO2 in Air

In this study, the reliability of NDIR-based sensors was explored by evaluating the comparability between measurement systems in the near real-time analysis of CO2. For this purpose, replicate analyses were performed using sensors of two different model types (H-550 and B-530, ELT Company, Korea). Three replicate data of each sensor type collected continuously by side-by-side analysis in three second intervals (a duration of 304 hour) were evaluated for the relative performance of NDIR sensors. The reproducibility of sensors, when assessed by relative standard error (RSE %) values of all sensor units, showed moderate changes with time with the overall mean of 2.33%. When CO2 measurements from all NDIR sensor units were evaluated by correlation analysis, the results showed strong comparability, regardless of the model type. The overall results of this study suggest that NDIR sensors are reliable enough to produce highly comparable data at least in a relative sense.

Airborne mercury pollution from a large oil spill accident on the west coast of Korea

Atmospheric mercury pollution was recognized after a large oil spill on the west coast of Korea on 7 December 2007. In this study, the concentrations of gaseous elemental mercury (GEM: Hg(0)) in air were measured both shortly after the oil spill ( approximately 100h) and 1month after the accident near the accident site. When the Hg concentration levels were compared between two seashore sites and two parallel sites offshore, the values tend to decrease further offshore. The unusual rise in Hg concentration levels observed on the seashore area shortly after the accident (mean of 16.4+/-9.85ngm(-3)) dropped dramatically after 1month with active cleanup activities (2.99+/-1.40ngm(-3)). Because of the connection between crude oil and Hg (one of the major impurities), the unusual rise in the atmospheric Hg after the oil spill can be explained by the active evasion of Hg from the spilled crude oil. Although Hg levels determined a few days after the accident did not exceed the reference exposure limits (REL) proposed by several agencies, the early build-up of elemental mercury level due to the oil spill might have exerted certain impacts on the surrounding environments.

The fundamental properties of the direct injection method in the analysis of gaseous reduced sulfur by gas chromatography with a pulsed flame photometric detector

In this study, the fundamental aspects of gas chromatography with a pulsed flame photometric detector were investigated through the calibration of gaseous reduced sulfur compounds based on the direct injection method. Gaseous standards of five reduced sulfur compounds (hydrogen sulfide, methane thiol, dimethyl sulfide, carbon disulfide, and dimethyl disulfide) were calibrated as a function of injection volume and concentration level. The results were evaluated by means of two contrasting calibration approaches: fixed standard concentration method (variable volumetric injection of standard gases prepared at a given concentration) and fixed standard volume method (injection of multiple standards with varying concentrations at a given volume). The optimum detection limit values of reduced sulfur compounds, when estimated at 100microL of injection volume, ranged from 2.37pg (carbon disulfide) to 4.89pg (dimethyl sulfide). Although these detection limit values improved gradually with decreasing injection volume, the minimum detectable concentration (e.g., in nmolmol(-1) scale) remained constant due to a balance by the sample volume reduction. The linearity property of pulsed flame photometric detector also appeared to vary dynamically with changes in its sensitivity. According to this study, the performance of pulsed flame photometric detector, when tested by direct injection method, is highly reliable to precisely describe the behavior of reduced sulfur compounds above approximately 20nmolmol(-1).

BBQ charcoal as an important source of mercury emission

In this study, the environmental significance of mercury emission has been investigated with respect to the use of the barbecue (BBQ) charcoal. For this purpose, emission gas samples collected from a total of 11 barbecue charcoal products commonly available in the Korean market were analyzed. All of these products consist of both domestic (4 types) and imported products (7 types from three countries). The emission concentration of Hg varied widely from sample to sample ranging from 114 to 496ngm(-3). The amount of Hg emission appeared to be affected by the diverse nature of raw materials and/or the processes involved in their production. In light of the recent reference exposure limits (REL) of Hg, it can be a potential threat to human health. As such, a proper regulation is desirable from a toxicological viewpoint to reduce the potential risk associated with the use of BBQ charcoal.

Comparative analysis of odorous volatile organic compounds between direct injection and solid-phase microextraction: Development and validation of a gas chromatography–mass spectrometry-based methodology

In this study, the feasibility of GC-MS was evaluated for the quantification of odorous volatile organic compounds (VOCs) in environmental samples. These included methyl ethyl ketone, isobutyl alcohol, methyl isobutyl ketone, and butyl acetate plus benzene, toluene, and xylene (BTX). For this purpose, the gaseous standard for these VOCs were analyzed by GC-MS with the aid of both direct injection (DI) into the GC injector and solid-phase microextraction (SPME). The liquid phase standard prepared independently was tested additionally by the DI method as a reference to gaseous calibration. The detection limit (DL) values, when tested for basic quality assurance in this study, showed large differences between DI (0.002-0.007 ng) and SPME method (1.03-1.81 ng) in terms of absolute mass. The DL values, when expressed in terms of concentration (v/v), showed considerable improvement in SPME (below 0.40 nmol mol(-1)) relative to the DI method (approximately 6-15 nmol mol(-1)). The reliability of the GC-MS method was further validated through an analysis of real environmental samples collected from an industrial area.

An evaluation of volatile compounds released from containers commonly used in circulation of sports beverages

In an effort to identify and quantify important volatile organic compounds (VOCs) released from sports beverage containers commonly used for storage and distribution, three brands of sports beverages with poly ethylene terephthalate (PET) and metal cans were analyzed through headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Out of 80 volatile compounds identified from all container types, I-limonene recorded the highest concentration (34.3-118 pmol mol(-1)) along with 12 other VOCs detected most frequently (more than 3 out of all 6 products) such as 2-methyl-6-methylene-2,7-octadiene, alpha-terpineol, decanaldehyde, and p-isopropyltoluene. When each container was filled up with water and analyzed after a long-term storage (49 days), a total of 14 VOCs were detected. According to our analysis, all the VOCs detected from either beverage or container materials were below the safety limits prescribed previously by diverse agencies. However, an extension of these analyses may be necessary for other beverage types, as certain VOCs can be migrated from container materials.

DIAGNOSTIC ANALYSIS OF OFFENSIVE ODORANTS IN A LARGE MUNICIPAL WASTE TREATMENT PLANT IN AN URBAN AREA

A diagnostic study was conducted to examine the effectiveness of malodor removal from a large-scale municipal waste treatment plant in an urban area. To this end, the odor pollution status was investigated from a total of 16 spots in the treatment facility to cover the dual treatment lines consisting of regenerative thermal oxidation (first stage) and a wet chemical scrubber (second stage). As a simple means to learn more about the odorant removal efficiency of different treatment units, samples collected from ambient spots as well as before and after each treatment unit were analyzed for 22 key offensive odorants (i.e., reduced sulfur compounds, carbonyl compounds, nitrogenous compounds, volatile organic compounds, and fatty acids) along with dilution-to-threshold ratios based on the air dilution sensory test. The removal patterns differed greatly between different odorant groups across different processing units. The effectiveness of this dual treatment system was optimized for such odorants as hydrogen sulfide and ammonia, while it was not the case for others (e.g., some aldehydes and organic acids). The results thus suggest the need for the validation of the efficiency in many types of odor processing units and for establishing new control techniques to cover a list of odorants un-subordinate to preexisting methods.

Airborne foliar transfer of PM bound heavy metals in Cassia siamea: A less common route of heavy metal accumulation

In order to investigate possible foliar transfer of toxic heavy metals, concentrations of Cd, Pb, and Fe were measured in samples of: Cassia siamea leaves (a common tree) Cassia siamea foliar dust, nearby road dust, and soil (Cassia siamea tree roots) at six different sites in/around the Bilaspur industrial area and a control site on the university campus. Bilaspur is located in a subtropical central Indian region. The enrichment factor (EF) values of Pb and Cd, when derived using the crustal and measured soil Fe data as reference, indicated significant anthropogenic contributions to Pb and Cd regional pollution. Based on correlation analysis and scanning electron microscopy (SEM) observations, it was evident that Pb and Cd in foliar part of Cassia siamea were largely from airborne sources. The SEM studies of leaf confirmed that leaf morphology (epidermis, trichome, and stomata) of Cassia siamea helped accumulate the toxic metals from deposited particulate matter (PM). There is a line of evidence that the leaf of Cassia siamea was able to entrap PM in respirable suspended particulate matter (RSPM) range (i.e., both in fine and coarse fractions). The overall results of this study suggest that Cassia siamea can be a potential plant species to control the pollution of PM and PM-bound metals (Pb and Cd) in affected areas.

Analytical bias among different gas chromatographic approaches using standard BTX gases and exhaust samples

In this study, the analytical compatibility of the gas chromatographic (GC) approach was evaluated through a cross-calibration exercise. To this end, three aromatic volatile organic compounds (VOCs: benzene, toluene, and p-xylene (BTX)) were simultaneously analyzed with four individual instrumental setups (type I = GC with MS plus solid phase microextraction (SPME) method, II = GC with flame ionization detection (FID) plus SPME, III = fast GC-FID plus SPME, and IV = GC-FID plus air server/thermal desorption (AS/TD) method). A comparison of basic quality assurance (QA) data revealed considerable differences in DL values among the methods with moderate variabilities in the intercompound sensitivity. In light of the differences in detection properties, the analytical bias involved for each methodological approach was assessed by the relative relationship between analytes and basic operating conditions. The results suggest that the analysis of environmental samples at ultra-low concentration levels (at or below ppb level) can be subject to diverse sources of bias. Although detection properties of target compounds seem to be affected by the combined effects of various factors, changes in the sample concentration levels were seen to be the most consistent under the experimental setups analyzed in this study.