Breathing Height Research Articles

Artificial turf: chemical flux and development of silicone wristband partitioning coefficients

This work uses passive samplers to identify PAHs and OPAHs not previously associated with artificial turf, and to provide the first quantitative measure of in situ flux of semi-volatile contaminants on artificial turf fields. Both air (1.5-m height) and turf air (immediately above turf surface) were sampled using two sampling materials: low-density polyethylene and silicone. Utilizing a broad targeted screen, we assess both artificial turf and samples of crumb rubber for over 1530 chemicals including pesticides, phthalates, and personal care products. We report the presence of 25 chemicals that have not yet been reported in artificial turf literature, including some with known human effects. The samplers were also quantitatively analyzed for polycyclic aromatic hydrocarbons yielding gas-phase concentrations at breathing height and surface level—the first such report on an artificial turf outdoor field. Turf pore-air and air chemicals were highly correlated at all sites, and particularly at the recently installed indoor site. Flux of chemicals between air and turf surface appear to follow field age although more research is needed to confirm this trend. The thermal extraction process and silicone passive samplers used are suitable for larger-scale environmental sampling campaigns that aim for less solvent and sample processing. By co-deploying silicone passive samplers and conventional low-density polyethylene, partitioning coefficients are derived that can be used for future silicone passive air sampling environmental assessment. This study provides an initial demonstration that passive samplers can be used to quantify volatile and semi-volatile organic chemicals from artificial turf.

Effect of moving vehicles on pollutant dispersion in street canyon by using dynamic mesh updating method

Moving vehicles exert a considerable influence on air flow and turbulence within urban street canyons, which is an important consideration for the pollutant dispersion and thus, local air quality management. In order to evaluate vehicle-induced turbulence and its contribution to pollutant dispersion, this study proposes a computational fluid dynamics based simulation methodology that uses a dynamic mesh updating method. The unsteady RNG k-ε turbulence model was employed to investigate the turbulent kinetic energy (TKE) induced by vehicle movement and pollutant profile in the target street canyon. The simulation accuracy is successfully validated against a published wind tunnel experiment. The results demonstrate that: (1) The TKE is mainly located behind the vehicle, and the magnitude of the TKE around the moving vehicle body far exceeds that of stationary vehicles; (2) Travelling speed has a significant influence on the TKE. When the moving speed is 15 m/s, its TKE near the tail is about 1.8 times and 6.3 times than that at 10 m/s and at 5 m/s, respectively; (3) Vehicle movement greatly contributes to pollutant dispersion. Compared to no vehicle movement (V = 0 m/s), vehicle-induced turbulence with V above 5 m/s can reduce the carbon monoxide concentration by about 4% at breathing height.

Impacts of forest structure on precipitation interception and run‐off generation in a semiarid region in northern China

AbstractWater resource scarcity and uneven distribution are 2 major environmental issues in China today. Forest structure is a dominant factor that influences hydrological processes, but the specific interactions remain uncertain due to the predominant use of individual or 1‐dimensional forest structure metrics in previous studies. In this study, forest structures in 8 run‐off plots on Mount Miaofeng in north China were parameterized by metrics of different dimensionalities. The relation between canopy interception and forest structure, shrub/litter interception, and forest structure as well as run‐off and forest structure were analysed by regression method and validated by leave‐one‐out cross test. The results showed that canopy interception rates ranged from less than 0.10 all the way to 0.80, affected by forest structure and precipitation, with interception rate decreasing logarithmically as precipitation increased. Forests with a larger canopy area (CA), leaf area index (LAI), and higher average height (H) had a narrow range of canopy interception rates, and forest with larger value of diameters at breath height (DBH), H, LAI, vertical heterogeneity coefficient (T), and structure complexity index (SCI) had higher interception rates. Forests with higher value of DBH, H, and horizontal heterogeneity coefficient (R) had higher shrub/litter interception rates on the forest floor. The run‐off coefficient was only significantly associated with LAI, T, and SCI. The validation test indicated that regression analysis of canopy interception rates and shrub interception are reliable and SCI is a key factor to influence the run‐off coefficient. However, the regression results of litter interception have a relatively large error. According to the results, to reduce the risks of the landslides and floods, forest managers should complicate the canopy and preserve trees with thicker stems and larger canopies. By contrast, to obtain more water resource from run‐off in arid regions, forest managers should harvest trees with large canopies and construct complex vertical structures by intermediate cutting.

Volumetric equation development and carbon storage estimation of urban forest in Daejeon, Korea

ABSTRACTThis study was performed to develop equations which are suitable for estimating carbon storage of urban forest in Daejeon, Korea and to evaluate carbon storage and sequestration of urban forest using developed equations. Among the urban forest, we only concern about the major street tree species (Platanus occidentalis, Ginko biloba, Zelkova serrata, Chionanthus retusa, and Acer pseudo-sieboldianum) which are planted alongside a road for vehicles as well as pedestrian in urban area. Developed equations showed R2 of 0.93 (Z. serrata), 0.67 (P. occidentalis), 0.96 (G. biloba), 0.93 (C. retusa), and 0.88 (A. pseudo-sieboldianum) when they were derived from diameter at breath height (DBH). Using the DBH-volume equation, the five street tree species (P. occidentalis, G. biloba, Z. serrata, C. retusa, and A. pseudo-sieboldianum), which account for 70% of total street trees in the Daejeon, stored about 4290 tons of carbon. Among the five street tree species, P. occidentalis constituted more than 50% of total stored carbon and followed by G. biloba. Based on the carbon storage, five street tree species can sequestrate 216 tons of carbon annually which means that 793 tons of carbon dioxide (CO2) removal from the air every year.

Impacts of Traffic Tidal Flow on Pollutant Dispersion in a Non-Uniform Urban Street Canyon

A three-dimensional geometrical model was established based on a section of street canyons in the 2nd Ring Road of Wuhan, China, and a mathematical model describing the fluid flow and pollutant dispersion characteristics in the street canyon was developed. The effect of traffic tidal flow was investigated based on the measurement results of the passing vehicles as the pollution source of the CFD method and on the spatial distribution of pollutants under various ambient crosswinds. Numerical investigation results indicated that: (i) in this three-dimensional asymmetrical shallow street canyon, if the pollution source followed a non-uniform distribution due to the traffic tidal flow and the wind flow was perpendicular to the street, a leeward side source intensity stronger than the windward side intensity would cause an expansion of the pollution space even if the total source in the street is equal. When the ambient wind speed is 3 m/s, the pollutant source intensity near the leeward side that is stronger than that near the windward side (R = 2, R = 3, and R = 5) leads to an increased average concentration of CO at pedestrian breathing height by 26%, 37%, and 41%, respectively. (R is the ratio parameter of the left side pollution source and the right side pollution source); (ii) However, this feature will become less significant with increasing wind speeds and changes of wind direction; (iii) the pollution source intensity exerted a decisive influence on the pollutant level in the street canyon. With the decrease of the pollution source intensity, the pollutant concentration decreased proportionally.

Sequential Extractions and Toxicity Potential of Trace Metals Absorbed into Airborne Particles in an Urban Atmosphere of Southwestern Nigeria.

The paper investigates the hypothesis that biotoxicities of trace metals depend not only on the concentration as expressed by the total amount, but also on their geochemical fractions and bioavailability. Airborne particles were collected using SKC Air Check XR 5000 high volume Sampler at a human breathing height of 1.5–2.0 meters, during the dry season months from November 2014 to March 2015 at different locations in Akure (7°10′N and 5°15′E). The geochemical-based sequential extractions were performed on the particles using a series of increasingly stringent solutions selected to extract metals (Cd, Cu, Cr, Ni, Pb, Zn, and Mn) into four operational geochemical phases—exchangeable, reducible, organic, and residual—and then quantified using an Atomic Absorption Spectrophotometer. The results showed metals concentration of order Pb > Cr > Cd > Zn > Ni > Cu > Mn. However, most metals in the samples exist in nonmobile fractions: exchangeable (6.43–16.2%), reducible (32.58–47.39%), organic (4.73–9.88%), and residual (18.28–27.53%). The pollution indices show ingestion as the leading route of metal exposure, with noncarcinogenic (HQ) and cancer risk (HI) for humans in the area being higher than 1.0 × 10−4, indicating a health threat.

ABOVEGROUND BIOMASS OF COMMON OAK WINDBREAKS IN THE CENTRAL PART OF UKRAINE

The article is devoted to research of above-ground biomass of oak (Quercus robur L.) windbreaks. Described are the morphological, biological, ecological and forest meliorative properties of common oak growing in windbreaks. The dependence between the amount of biomass components and the main mensurational and meliorative indices such as protective height and openness in the crowns of windbreaks has been established. As a result, mathematic models for the assessment of both the above-ground components of a tree,the crown, and a windbreak, as a whole, have been developed. It is determined that the relative density of the trunk has less accuracy than openness in the crown in the assessment of the components of above-ground phytomass of a windbreak. For a separate tree of 36 cm in diameter at breath height, 24 m in height, a 0.8 windbreak density and a 10 % openness of crown in windbreak, the share of trunk biomass is higher in a massive stand in comparison with a windbreak. However, the crown biomass in a windbreak is 6% larger than in a massive stand. The standards for determination of the amount of phytomass components for trunks and crowns of separate trees and oak windbreaks, as well as that of sequestered carbon have been developed. The developed models and standards were analyzed. and the structure of phytomass on the components and sequestered carbon done. The comparative analyze has revealed the trends towards increased share of crown phytomass in the oak windbreaks with increasing their biometric characteristics as compared to massive stands.

Where to locate transit stops: Cross-intersection profiles of ultrafine particles and implications for pedestrian exposure.

Epidemiological studies have shown that exposure to traffic-related pollutants increases incidence of adverse health outcomes. Transit users in cities across the globe commonly spend 15-45min or more waiting at transit stops each day, often at locations with high levels of pollution from traffic. Here, we investigate the characteristics of concentration profiles of ultrafine particles (UFP) with 5m spatial resolution across intersections, to determine the best place to site transit stops to minimize exposures. Cross-intersection UFP profiles were derived from 1744 profiles covering 90m before and after each intersection center with a mobile monitoring platform. Measurements were made at 10 signalized intersections located at six urban sites, each with a distinct built environment, during both mornings and afternoons. Measurements were made within 1.5m of the sidewalk and approximately at breathing height (1.5m above ground level) to approximate sidewalk exposures. UFP profiles were strongly influenced by high emissions from vehicle stops and accelerations, and peaked within 30m of intersection centers; from there concentrations decreased sharply with distance. Peak concentrations averaged about 90% higher than the minima along the block. They were accompanied by more frequent and larger transient concentration spikes, increasing the chance of people near the intersection being exposed to both short-term extremely high concentration spikes and higher average concentrations. The decays are somewhat larger before the intersection than after the intersection, however as siting transit stops after intersections is preferred for smooth traffic flow, we focus on after the intersection. Simple time-duration exposure calculations combined with breathing rates suggest moving a bus stop from 20 to 40-50m after the intersection can reduce transit-users' exposure levels to total UFP substantially, in proportion to the reciprocal of the magnitude of elevation at the intersection.

Urbanity as a determinant of exposure to grass pollen in Helsinki Metropolitan area, Finland.

Little is known about the levels of exposure to grass pollen in urban environments. We assessed the spatio-temporal variation of grass pollen concentrations and the role of urbanity as a determinant of grass pollen exposure in the Helsinki Metropolitan area. We monitored grass pollen concentrations in 2013 at 16 sites during the peak pollen season by using rotorod-type samplers at the breathing height. The sites were in the cities of Helsinki and Espoo, Finland, and formed city-specific lines that represented urban-rural gradient. The monitoring sites were both visually and based on land use data ranked as high to low (graded 1 to 8) pollen area. The lowest grass pollen concentrations were observed in the most urban sites compared to the least urban sites (mean 3.6 vs. 6.8 grains/m3 in Helsinki; P<0.0001, and 5.2 vs. 87.5 grains/m3 in Espoo; P<0.0001). Significant differences were observed between concentrations measured in morning periods compared to afternoon periods (4.9 vs. 5.4 in Helsinki, P = 0.0186, and 21.8 vs. 67.1 in Espoo, P = 0.0004). The mean pollen concentration increased with decreasing urbanity both in Helsinki (0.59 grains/m3 per urbanity rank, 95% CI 0.25–0.93) and Espoo (8.42, 6.23–10.61). Pollen concentrations were highest in the afternoons and they were related to the ambient temperature. Urbanity was a strong and significant determinant of pollen exposure in two Finnish cities. Pollen exposure can periodically reach such high levels even in the most urban environments that can cause allergic reactions among individuals with allergies.

Occupants' perception of air movements and air quality in a simulated classroom with an intermittent air supply system

The study reported herein builds on occupant response to an intermittent air jet strategy (IAJS), which creates periodic airflow and non-isothermal conditions in the occupied zone. Previous research has highlighted benefits of IAJS for the thermal climate and energy saving potential in view of human thermal perception of the indoor environment. The study herein explores the occupant acceptability of air movements and perceived indoor air quality. Thirty-six participants were exposed to three room air temperatures (nominal: 22.5℃, 25.5℃ and 28.5℃) with each having four air speed conditions (nominal: &lt; 0.15 m/s under mixing ventilation (MV) and 0.4, 0.6 and 0.8 m/s under IAJS) measured at the breathing height (1.1 m). The results show that participants preferred low air movements at lower temperatures and high air movements at higher temperatures. A model to predict percentage satisfied with intermittent air movements was developed. The model predicts that 87% of occupants, in compliance with ASHRAE 55-2013 standard, will find intermittent air movements acceptable between 23.7℃ and 29.1℃ within an air speed range of 0.4 to 0.8 m/s. IAJS also improved participants' perception of air quality in conditions deemed poor under MV. The findings support the potential of IAJS as a primary ventilation system in high occupant spaces such as classrooms.

VOC level control by ventilation improvement of Flexography printing room using CFD modeling

Using Computational Fluid Dynamics (CFD) technique, the dispersion contours and the exposure rate of Flexographic printing workers to VOCs in a printing department is evaluated. Firstly, VOCs distribution is determined in the printing room due to the existing ventilation system. Through next steps, 4 scenarios for lowering VOCs concentration and its exposure rate to workers are analyzed. Concentration distributions of ethylene glycol (MEG) as a representative of VOCs are determined for 4 scenarios. The results show that, regarding the existing ventilation, the concentration of MEG at the breathing height is 1×10-5 mg/m3 and it is higher than the standard permissible level. Finally, the findings of this study lead to lowered VOCs concentrations to 13.87×10-9 mg/m3 via changing the ventilation system for the Flexography Printing Room.

A contribution to the study of airborne Citrus pollen in Córdoba, southern Spain

Citrus species, and especially oranges, are widely grown in Córdoba (southern Spain) both as ornamentals (Citrus aurantium) and as cash crops (Citrus sinensis). There has been little research into the incidence of orange-pollen allergy in the local population. Given the abundant presence of orange trees in Córdoba, a study was designed to determine local Citrus pollen counts at human height in areas where these trees are densely planted. Although standard aerobiological studies report negligible airborne Citrus pollen counts, the samplers used are located at greater heights and in open areas; as a result, large Citrus pollen grains are not recorded. It was found that when Hirst-type volumetric samplers were placed on the roof of a building – the recommended position for aerobiological research – airborne Citrus pollen counts were very low. By contrast, portable samplers placed at human breathing height recorded very high counts, reaching around 2000pollen grains/m3 during the peak day. This finding suggests that greater attention should be paid to the potential negative impact on the local population, given that the sparse research has highlighted the allergenic nature of orange pollen. Citrus pollen could have an adverse local health impact in areas where orange-trees are densely planted, particularly given reported cross-reactivity with other pollen types. However, further aerobiological and clinical research into Citrus pollen is required in order to draw wholly reliable conclusions.

계사 및 우사 내 암모니아 및 황화수소 노출농도 평가

Objectives: There are many hazardous agents at livestock farms. In particular, gases can be detrimental to both workers and animals. This study evaluated ammonia and hydrogen sulfide concentrations in broiler hen barns and beef cattle barns according to sampling location and height. Methods: Three broiler hen barns and three beef cattle barns were selected for gas monitoring in this study. Ammonia and hydrogen sulfide concentrations were measured using a direct-reading instrument which could measure the target gases simultaneously. Gas monitoring was conducted at human breathing height and animal breathing height at three points in each livestock farm. Results: Ammonia concentrations at the broiler hen barns ranged from 3.3 to 12.5 ppm by sampling location and height, but hydrogen sulfide was not detected. In the beef cattle barns, ammonia ranged from 3.1 to 16.3 ppm and low concentrations of hydrogen sulfide were detected at some animal breathing heights. The gas concentrations detected at each livestock farm were significantly higher in the animal breathing zones than in human breathing zones (p<0.0001). Conclusions: We found a difference in gas concentrations between human breathing zones and animal breathing zones. Gas monitoring should be conducted to improve the related environment considering both workers' and animals' health and safety.

Greater nitrogen dioxide concentrations at child versus adult breathing heights close to urban main road kerbside.

Nitrogen dioxide (NO2) is a ubiquitous air pollutant with high concentrations particularly close to main roads. The focus of this study was on possible differences in NO2 concentrations between adult and child heights as a function of different distances from heavily trafficked roads in urban areas. Passive diffusion tubes were used to measure NO2 concentrations at heights of 0.8 m (approximate inhalation height of children and closer to vehicle exhaust height) and 2.0 m (approximate inhalation height of adults) above the ground at a number of locations and over several weeks in the city of Edinburgh, UK. Evidence for significant differences in NO2 between heights was observed up to at least 1.2 m from kerbside of busy roads, with tubes at 0.8 m measuring concentrations 5–15 % (a few μg m−3) greater than at 2.0 m. The vertical NO2 concentration difference was not observable at distances 2.5 m or greater from the kerbside. Fitting of horizontal transects of NO2 concentrations away from main roads demonstrated the strong influence of wind speed in yielding faster fall-off in NO2 concentration from the roadside, and in near-ground vertical gradient in NO2, and lower background NO2 concentrations. These observations have potential public health implications for differential NO2 exposures between children walking, or in buggies, close to heavily trafficked urban roads compared with adults.

航空レーザーによるヒノキ・スギの森林蓄積推定－林分特性の違いを考慮した蓄積推定モデルの開発－

I developed a model to estimate stand volumes using LiDAR data. Stand volumes (v) are often estimated by linear regression model using spatial volume (V), v＝aV or v＝aV＋b, where a and b as constant. This method is easy to apply, but its accuracy is known to be low. Belief of taking “a” as constant may worth for reconsideration. The concept of “Stock Ratio (s)” -defined as s＝v/V is newly proposed in this study. I focused on five representative stand characters-species, diameter of breath height, slope, height to diameter ratio and Hart-Becking index and examined the relation between these factors and Stock Ratio using 6,000 trees data obtained in field measurements. The results strongly suggested that species and Hart-Becking index have an apparent relation with Stock Ratio. Hence, it is clear that Stock Ratio will differ among species and Hart-Becking index. The relation can be modeled as s＝Bse(－As×Sr) where Sr is Hart-Becking index and, As and Bs are the constant by species. Introducing the estimation of Stock Ratio with above two factors which is proposed in this study will improve the accuracy of the estimation for the stand volume (i.e. v＝sV＝Bse(－As×Sr)V) than conventional methods.

Atmospheric Volatile Organic Compounds and Ozone Creation Potential in an Urban Center of Southern Nigeria

The relative contribution of individual volatile organic compounds (VOC) species to photochemical ozone formation depends on their atmospheric concentrations and their oxidation mechanism. In an attempt to evaluate the ozone creation potential of ambient VOCs captured in an urban settlement of Benin City, Nigeria, the VOCs concentrations data collected in field studies at nine measurement sites of different air quality in the city and a background site were analysed. Air samples were collected at human breathing height of 1.5 meters from ground level at each site. Active sampling method using the low volume sampling pump (Acuro, Drager, Lubeck, Germany) was used to drawn the air into the tube; the absorbent was Chromosorb 106. The sampling periods were between May 2010 and June 2011; the period covered both dry and wet seasons. The adsorbed gases were desorbed using solvent extraction method with carbon disulphide as solvent. The extracted solutions were analyzed with gas chromatography and mass spectrometer. The observed concentrations of individual VOCs were determined and maximum incremental reactivity (MIR) coefficient along with rate constants of VOC-OH reactions were applied to assess the ozone formation potential of individual VOC in the ambient atmosphere. Sixteen VOC species were observed at various sites with mixing height in decreasing order: toluene (5.82), mp-xylene (3.58), ethylbenzene (3.46), benzene (2.29), and n-butane (0.84). The ozone formation potential study revealed that, ranking by propyl-equivalent, the alkanes included in this study account for 58% of the total propyl-equivalent concentration. The total ozone creation potential in the atmosphere of the Benin City was calculated to be 281.1 µg/m3. A comparison of total ozone formation potential (OFP) in our study with results obtained from other cities of the world revealed that the total concentration of ozone production in our study is threefold lower than the values reported in China city of Foshan. It is suggested that the sources of this pollutant need to be monitored in the area as a way of curtailing the impact of ozone in this city.

Atmospheric dispersion of natural carbon dioxide emissions on Vulcano Island, Italy

AbstractLa Fossa quiescent volcano and its surrounding area on the Island of Vulcano (Italy) are characterized by intensive, persistent degassing through both fumaroles and diffuse soil emissions. Periodic degassing crises occur, with marked increase in temperature and steam and gas output (mostly CO2) from crater fumaroles and in CO2 soil diffuse emission from the crater area as well as from the volcano flanks and base. The gas hazard of the most inhabited part of the island, Vulcano Porto, was investigated by simulating the CO2 dispersion in the atmosphere under different wind conditions. The DISGAS (DISpersion of GAS) code, an Eulerian model based on advection‐diffusion equations, was used together with the mass‐consistent Diagnostic Wind Model. Numerical simulations were validated by measurements of air CO2 concentration inside the village and along the crater's rim by means of a Soil CO2 Automatic Station and a Tunable Diode Laser device. The results show that in the village of Vulcano Porto, the CO2 air concentration is mostly due to local soil degassing, while the contribution from the crater gas emission is negligible at the breathing height for humans and always remains well below the lowest indoor CO2 concentration threshold recommended by the health authorities (1000 ppm). Outdoor excess CO2 maxima up to 200 ppm above local background CO2 air concentration are estimated in the center of the village and up to 100 ppm in other zones. However, in some ground excavations or in basements the health code threshold can be exceeded. In the crater area, because of the combined effect of fumaroles and diffuse soil emissions, CO2 air concentrations can reach 5000–7000 ppm in low‐wind conditions and pose a health hazard for visitors.

Estructura de una población del árbol Peltogyne purpurea (Cesalpinaceae) en un bosque intervenido de la Península de Osa, Costa Rica

The regeneration of the rain forest tree Peltogyne purpururea Pittier after selective logging was studied in Mogos, Osa Peninsula, Costa Rica. The distribution of all adult trees of P. purpurea according to diameter at breath height (dbh) categories revealed that the distribution of the adult trees followed a bell-shaped curve. The largest number of individuals was found in the 70 to 80 cm dbh category. We did not find any significant differences in the distribution of saplings around seed-producing trees. There were similar numbers of saplings in the four transects established around each reproductive tree following the four cardinal directions. Overall, the majority of the saplings were found in the first meters around each seed-producing tree. There was another peak in the number of saplings at the distance where the crown of the tree ended. Logging can negatively affect the regeneration of P. purpurea.

Large trees as key elements of carbon storage and dynamics after selective logging in the Eastern Amazon

The long term effect of Reduced-Impact Logging (RIL) on above-ground live biomass (AGB) dynamics was investigated in 18 1-ha logged over permanent sample plots set up in a terra firme rain forest in the Eastern Amazon (Brazil, Paragominas). Both tree survival and growth were investigated among three Diameter at Breath Height (DBH) classes (20–40, 40–60, ⩾60cm) to assess the contribution of each DBH class to the post-logging AGB recovery. Before logging, mean tree density and AGB per plot (dbh⩾20cm) were 187±14 trees ha−1 and 377.6±62.8Mgha−1 respectively. Although big trees (dbh⩾60cm) only represented 9.3% of the total tree density, they gathered almost half of total AGB. During the post-logging period (8years), the mortality of large trees was found to drive the annual net changes and largely overcame the AGB gain in the smaller DBH classes. Indeed, plots with high post-logging mortality of large trees showed negative carbon balance t over the study period (8years). The over mortality of large trees injured by logging contributed significantly to the annual AGB losses (up to 40%) in the first years after logging. Due to the overwhelming importance of this size class in carbon stocks and dynamic, reducing logging damages and intensity might have great impact in the post-logging biomass dynamics. We estimated that reducing logging intensity from 6 to 3 stems ha−1 would save 27.7Mg C ha−1 for a 35years rotation cycle. To compensate this loss of profits, compensatory payments of avoided CO2 emission should worth US $ 6.5/Mg of CO2. This price falls into the range of prices of the international carbon market. Sustainable forest management aiming at enhancing carbon stocks could therefore promote the preservation of the large trees. At our study site, we recommend the adoption of a maximum diameter cutting limit of 110cm.

Cancer risk of incremental exposure to polycyclic aromatic hydrocarbons in electrocautery smoke for mastectomy personnel

BackgroundElectrocautery applications in surgical operations produce evasive odorous smoke in the cleanest operation rooms. Because of the incomplete combustion of electrical current in the tissues and blood vessels during electrocautery applications, electrocautery smoke (ES) containing significant unknown chemicals and biological forms is released. The potential hazards and cancer risk should be further investigated from the perspective of the occupational health of surgical staff.MethodsThe particle number concentration and the concentration of polycyclic aromatic hydrocarbons (PAHs) in ES were thoroughly investigated in 10 mastectomies to estimate the cancer risk for surgical staff. The particle number concentration and gaseous/particle PAHs at the surgeons’ and anesthetic technologists’ (AT) breathing heights were measured with a particle counter and filter/adsorbent samplers. PAHs were soxhlet-extracted, cleaned, and analyzed by gas chromatography/mass spectrometry.ResultsAbundant submicron particles and high PAH concentrations were found in ES during regular surgical mastectomies. Most particles in ES were in the size range of 0.3 to 0.5 μm, which may potentially penetrate through the medical masks into human respiration. The average particle/gaseous phase PAH concentrations at the surgeon’s breathing height were 131 and 1,415 ng/m3, respectively, which is 20 to 30 times higher than those in regular outdoor environments. By using a toxicity equivalency factor, the cancer risk for the surgeons and anesthetic technologists was calculated to be 117 × 10-6 and 270 × 10-6, respectively; the higher cancer risk for anesthetic technologists arises due to the longer working hours in operation rooms.ConclusionsThe carcinogenic effects of PAHs in ES on the occupational health of surgical staff should not be neglected. The use of an effective ES evacuator or smoke removal apparatus is strongly suggested to diminish the ES hazards to surgical staff.