Volatile Organic Air Pollutants Research Articles

Ambient BTEX levels over urban, suburban and rural areas in Malaysia

Benzene, toluene, ethylbenzene and xylene isomers (BTEX) are volatile organic air pollutants of concern which arise from natural and anthropogenic sources. This study aims to determine and evaluate the BTEX levels in ambient air in selected areas of Malaysia, namely: Kuala Lumpur (KL-urban), Penang (PG-urban), Bangi (BG-suburban), Langkawi (LGK-suburban) and the Danum Valley (DV-rural). Active sampling with sorbent tubes was applied in this study and samples were analysed using thermal desorption (TD) coupled with gas chromatography-mass spectrometry (GC-MS). The results show that the urban area of KL had the highest ΣBTEX (40.36 ± 6.99 μg/m3) followed by PG (30.82 ± 8.06 μg/m3). ΣBTEX concentrations in the suburban areas of LGK and BG were measured as 20.22 ± 11.42 μg/m3 and 12.36 ± 2.26 μg/m3, respectively. The rural area of DV had the lowest concentration of ΣBTEX (5.55 ± 2.54 μg/m3). The average toluene to benzene (T:B) ratio at KL, PG and LG were found to be within the range of 2.00–5.00 thus indicating vehicle emissions as the main source. The benzene level at both KL (7.43 μg/m3) and PG (5.12 μg/m3) were found to be slightly higher than the annual benchmark of 5 μg/m3 as suggested by the European Union (EU). The results of health risk assessments found that the cancer risk (CR) based on benzene concentrations in urban, suburban and rural areas was > 10−6 thus indicating a link between human cancer risks and ambient benzene exposure.

Adsorptive Removal of Formaldehyde from Air Using Mixed-Metal Oxides

Volatile organic air pollutants such as aldehyde compounds have been identified as progressively damaging chemicals impacting human health at small albeit dangerous quantities. This study focuses o...

Toxic volatile organic air pollutants across Canada: multi-year concentration trends, regional air quality modelling and source apportionment

A Unified Regional Air-quality Modelling System, AURAMS, was expanded to predict six toxic volatile organic compounds (VOCs) within a continental domain and two nested domains covering eastern and western Canada. The model predictions were evaluated against Environment Canada’s National Air Pollution Surveillance (NAPS) data set to assess the predictive capability of the model at daily and seasonal time scales. The predictions were also evaluated with satellite-derived column total maps for formaldehyde, carbon monoxide, and nitrogen dioxide. In general, the model showed fair to good predictive skill in terms of both correlation (R) and normalized mean bias (NMB) for benzene (R = 0.53 NMB = 26 %), formaldehyde (R = 0.73, NMB = −15 %) and acetaldehyde (R = 0.55, NMB = 29 %). For the other toxics VOCs, the model showed less predictive skill in the order 1,2,4-trimethylbenzene (R = 0.50, NMB = −41 %), 1,3-butadiene (R = 0.26, NMB = 40 %) and acrolein (R = 0.052, NMB = −51 %). The goal of this study was to apply an air quality model to assess the contribution of mobile sources to ambient levels of toxic VOCs at urban locations across Canada. The mobile source contribution varied in a complex manner for each species for different regions. For benzene and 1,2,4-trimethylbenzene, the mobile source contribution was in the range 40–65 % for major Canadian cities. The model predicted considerably lower mobile source contributions for rural locations in the Canadian Prairies, where other area sources dominate, such as the petrochemical industry. Measured concentration trends in toxics are also presented from 2004 to 2010. The primary emitted toxics declined gradually (13–16 % over 6 yr) whereas the toxic aldehydes showed no trend.

Effects of unregulated anthropogenic activities on mixing ratios of volatile organic air pollutants—A case study

During the months of October to November, many important festivals are celebrated in India. Celebration of these festivals are marked by extensive use of fireworks or pyrotechnics, bonfire, incense burning, open air community cooking, and temporary eateries using crude fuel such as coal, wood, kerosene, cow dung, burning of raw/semiwood, and coconut shells. The present study deals with the influence of these unregulated anthropogenic activities on ambient mixing level of volatile organic compounds (VOCs), especially some carbonyl compounds. The study was undertaken in the metropolitan city of Kolkata, India, with very high population density, which is even higher during festival period. The average total carbonyl level at different sites in Kolkata varied from 134.8 to 516.5 μg m−3 in pre-festival season, whereas in post-festival season the same varied from 252.2 to 589.3 μg m−3. Formaldehyde to acetaldehyde ratio altered from 0.62 in pre-festival season to 1.78 in post-festival season. Diurnal variation also altered, indicating variation in source composition of carbonyls. The total ozone forming potential calculated for all 14 carbonyls in pre-festival season increased by 35% in post-festival season. The effect of anthropogenic activities typical to the event of Diwali night characterized by intense execution of pyrotechnics resulted in significantly high level of carbonyl VOCs. Principal component analysis study for the event of Diwali shows clear contribution of the event on certain carbonyl VOCs. The results indicate elevated primary emissions of these pollutants and also their effect on formation of secondary pollutants. The study emphasizes the need of generating awareness among the communities in society as well as need for regulations to minimize the emissions and related hazards to the extent possible.Implications: Altered anthropogenic activities typical of festival season including extensive use of pyrotechnics affect ambient level of volatile organic compounds, especially some carbonyls. Such activities have considerable effect on interspecies ratio and diurnal variation. They also affect formation of secondary pollutants such as tropospheric ozone. Principal component analysis (PCA) study shows clear contribution of the pyrotechnics execution on certain carbonyl VOCs. The findings emphasize the need of generating awareness in society and need for regulations to minimize the emissions.

Bindered anthracite briquettes as fuel alternative to metallurgical coke: Full scale performance in cupola furnaces

The authors have developed bindered anthracite briquettes that can replace conventional coke as a fuel in foundry cupolas. The anthracite briquettes included fine anthracite grains that were bindered together with collagen, lignin and silicon. These binders gave the briquettes high mechanical strength through the full spectrum of temperatures encountered in a foundry cupola furnace – from ambient temperature up to 1550°C. The bindered anthracite briquettes offered the same structural strength and fuel content as has conventional foundry grade coke. The conventional coking process involves pyrolyzing coal at 1000°C for a day; and this consumes about 15% of the raw coal’s energy, while releasing volatile organic air pollutants. In contrast, the briquetting process consumes scant energy, without releasing pollutants. During two full-scale demonstrations that each employed 4 tons of these briquettes, the anthracite briquettes performed similarly to the foundry grade coke, while the briquettes replaced up to 25% of the coke. During briquette replacements, the cupola temperatures, off-gas CO/CO2 proportions, tuyere back-pressures, and metal-to-fuel ratios were maintained or improved. The iron castings produced during this briquette replacement were of the same high quality and composition as when mere coke was used; and these iron castings were sold. Observations through the tuyere windows – where oxygen-enriched air was lanced into the bottom of the cupola – showed that these anthracite briquettes reached the cupola’s melting zone while maintaining their physical integrity. Once these briquettes reached the level of the tuyere windows, they exhibited faster burning in the oxygen-enriched air than did conventional coke.

Perinatal Exposure to Hazardous Air Pollutants and Autism Spectrum Disorders at Age 8

Hazardous air pollutants are plausible candidate exposures for autism spectrum disorders. They have been explored in recent studies for their role in the development of these disorders. We used a prevalent case-control design to screen perinatal exposure to 35 hazardous air pollutants for further investigation in autism etiology. We included 383 children with autism spectrum disorders and, as controls, 2,829 children with speech and language impairment. All participants were identified from the records-based surveillance of 8-year-old children conducted by the Autism and Developmental Disabilities Monitoring Network in North Carolina (for children born in 1994 and 1996) and West Virginia (born in 1992 and 1994). Exposures to ambient concentrations of metal, particulate, and volatile organic air pollutants in the census tract of the child's birth residence were assigned from the 1996 National Air Toxics Assessment annual-average model. We estimated odds ratios (ORs) for autism spectrum disorders and corresponding 95% confidence intervals (CIs), comparing across the 20th and 80th percentiles of log-transformed hazardous air pollutant concentration among the selected controls, using semi-Bayes logistic models and adjusting for sampling variables (surveillance year and state), a priori demographic confounders from the birth certificate and census, and covarying air pollutants. We estimated many near-null ORs, including those for metals, established human neurodevelopmental toxicants, and several pollutants that were elevated in a similar study in California. Hazardous air pollutants with more precise and elevated OR estimates included methylene chloride, 1.4 (95% CI = 0.7-2.5), quinoline, 1.4 (1.0-2.2), and styrene, 1.8 (1.0-3.1). Our screening design was limited by exposure misclassification of air pollutants and the use of an alternate developmental disorder as the control group, both of which may have biased results toward the null. Despite these limitations, methylene chloride, quinoline, and styrene emerged (based on this analysis and prior epidemiologic evidence) as candidates that warrant further investigation for a possible role in autism etiology.

Impact of inclement weather on the characteristics of volatile organic compounds in ambient air at the Hsinchu Science Park in Taiwan

This study describes continuous monitoring of the volatile organic air pollutants, acetone and toluene, in Hsinchu Science Park (HSP) during an occurrence of inclement weather, i.e., a typhoon. Using a lab-designed sampling system coupled with a continuous automated GC–MS analysis system, a total of 53 polar and nonpolar compounds were identified and quantified. The concentration of polar compounds dropped sharply from 41.4 ppbv before the typhoon to the stage of no detection during the storm, but rose again after the typhoon. The amount of nonpolar compounds remained unaffected during the storm. The polar compounds were more affected by both the rainfall and wind than were the nonpolar compounds. The severity of air pollution strongly correlates with the concentration of acetone released into the atmosphere by a wastewater treatment facility. The system used in this study has been proved reliable while working in inclement weather condition; in addition, the results can probably be applied in the monitoring of the environment during the typhoon season in high-tech research areas.

Efficacy of Indoor Plants for the Removal of Single and Mixed Volatile Organic Pollutants and Physiological Effects of the Volatiles on the Plants

Foliage plants of Hedera helix L. (english ivy), Spathiphyllum wallisii Regal (peace lily), Syngonium podophyllum Schott. (nephthytis), and Cissus rhombifolia Vahl. (grape ivy) were evaluated for their ability to remove two indoor volatile organic air pollutants, benzene and toluene. Removal was monitored when the aerial portion of plants was exposed singly to 1 μL·L-1 or to 0.5 μL·L-1 of each gas in a closed environment over 6-hour periods during the day and the night. Selected physiological processes were assessed before and immediately after treatment to determine the effect of the gases on the plants. The effectiveness of plants in the removal of air pollutant(s) varied with species, time of day, and whether the gases were present singly or as a mixture. When exposed to a single gas, S. wallisii, S. podophyllum, and H. helix displayed higher removal efficiencies (ng·m-3·h-1·cm-2 leaf area) of either gas than C. rhombifolia during the day. The efficiency of removal changed when both gases were present; H. helix was substantially more effective in the removal of either benzene or toluene than the other species, with the removal of toluene more than double that of benzene. When exposed singly, the removal of both compounds was generally higher during the day than during the night for all species; however, when present simultaneously, H. helix removal efficiency during the night was similar to the day indicating that stomatal diffusion for english ivy was not a major factor. The results indicated an interaction between gases in uptake by the plant, the presence of different avenues for uptake, and the response of a single gas was not necessarily indicative of the response when other gases are present. Changes in the rates of photosynthesis, stomatal conductance, and transpiration before and after exposure indicated that the volatiles adversely affected the plants and the effects were not consistent across species and gases. Deleterious effects of volatile pollutants on indoor plants may be critical in their efficacy in improving indoor air quality and warrant further study.

Permeation passive sampling as a tool for the evaluation of indoor air quality

Time-weighted average concentrations of selected volatile organic air pollutants were determined in eight apartments in the city of Gdańsk (Poland) using permeation passive sampling. The samplers were recalibrated prior to use by controlled exposure to standard gaseous mixtures of the analytes. Small but statistically significant differences were found between the calibration constants determined initially and after one year of field use of the samplers for some of the analytes. The results obtained by the passive sampling technique were compared to those obtained by dynamic sampling using active charcoal-filled tubes, and dynamic sampling using Tenax-TA tubes. Overall, the results obtained by the three techniques were similar. Maximum allowable concentrations of the analytes were not exceeded in any of the apartments examined. The results of total volatile organic compounds determination indicated that some VOCs were unaccounted for in the experiment. The effect of outside air infiltration on indoor air quality was evaluated by comparing analyte concentrations in indoor air and in outdoor air in the very vicinity of the apartment. This effect was found to be minimal.

Modeling of the sorption and diffusion processes of volatile organic air pollutants in grape fruits.

A mathematical model for the description of the sorption and diffusion processes of gaseous toluene and p-xylene in fruits of grape has been proposed. This model is based on the Fick's II low regarding a particle with a spherical shape (such as the berry of grapevine) and describes changes of air pollutant concentrations in different layers of the fruit, that is, the wax, peel, and pulp, during an exposure to contaminated air. The mass transfer coefficient and diffusion coefficients in the respective layers can be estimated using the experimental values. The theoretical data and the results from the exposure under steady-state laboratory conditions were compared and showed a good applicability of the proposed model for the prediction of volatile air pollutant partitioning in grape berries.

Trichloroacetic acid as a phytotoxic air pollutant and the dose-response relationship for defoliation of Scots pine

Various ubiquitous volatile organic air pollutants (VOCs), especially C2-halocarbons, may be converted to secondary air pollutants that are phytotoxic and known as herbicides. One of these is trichloroacetic acid (TCA), found in concentrations ranging from 10 to 130 ng/g in the foliage of forest trees in northern Finland. TCA has been used as a herbicide against monocotyledonous weeds. It has formative effects, inhibits growth, and induces chlorosis and necrosis of light-exposed leaves, including those of woody plant species. Twenty Scots pine trees in an experimental stand 50 km southeast of Rovaniemi were sampled for correlation of TCA levels and needle loss. The trees located at the northwesterly edge of the stand could be divided into two groups, one more resistant to the phytotoxicant TCA than the second. The range of TCA concentrations in needles was 8–65 ng/g. The extent of defoliation (range 25–90%) was lower in the TCA-resistant group, with a gradient of 0.32% defoliation per unit TCA concentration; in the sensitive group, the correlation line had a steeper slope of 0.78% defoliation per unit TCA concentration. These two groups serve as a basis for further studies on morphological, anatomical, and biochemical parameters.

The micro-trap: An alternative to cryofocussing in capillary gas chromatography

For routine analyses involving numerous samples or for field operation of on-site instruments, cryogenic traps are inconvenient: their operation is timeconsuming and automation is technically demanding. complete trapping and efficient band-focussing may be achieved at ambient temperature with micro-traps packed with suitable sorbents. Two approaches have been evaluated: if the boiling points of the analytes are within a range of about 100°C, a single-sorbent trap and direct coupling to the column are recommended; for samples containing components wih widely different volatilities, a trap composed of two or more segments with complementary affinties and coupling to the chromatographic column under carrier-gas flow-reversion is preferable. The procedure has been evaluated for airborne C1 and C2-halocarbons; it is also applicable to trace analysis of other volatile organic air pollutants.

Evaluation of canisters for measuring emissions of volatile organic air pollutants from hazardous waste incineration.

Regulation to control air emissions of toxic organic compounds require the collection and analysis of effluent gas from low level sources such as hazardous waste incinerators. The standard SW-846 Method specifies the use of Tenax and Tenax/charcoal adsorbent traps for collection of volatile organics from incinerators. This study evaluates passivated stainless steel canisters as an alternative to adsorbent traps to eliminate some of the problems associated with adsorbent sampling. Initially the stability of 18 nonpolar, volatile organic compounds was determined in Summa-treated stainless steel canisters with greater than 100 ppmv HCl and saturated with water vapor. All 18 components were stable for a two-week period; however, an interference caused a 10-fold increase in the FID response of trichloroethylene, toluene, and chlorobenzene. No interference of the ECD response was found for any of the 11 compounds detected with the ECD including trichloroethylene. A pilot scale incinerator was sampled using canisters, and the destruction efficiency of 1,1,1-trichloroethane was determined at a concentration of less than 0.5 ppbv while determining 1,1-dichloroethylene, the major product of incomplete combustion, at a concentration of 8000 ppbv from the same sample.