Tape-stripping as a method for measuring dermal exposure to resin acids during wood pellet production

The purpose of this study was to develop a sensitive and specific method for quantifying dermal exposure to the resin acids 7-oxodehydroabietic acid (7-OXO), dehydroabietic acid (DHAA), abietic acid (AA), and pimaric acid (PA). In addition the method was evaluated in occupational settings during production of wood pellets. Tape-strips were spiked with the substances to evaluate the recovery of the acids from the tape. The removal efficiency of the tape was assessed by tape-stripping a specified area on a glass plate spiked with resin acids. The recovery of the acids from human skin in vivo was evaluated by applying acids in methanol onto the skin of volunteers. Occupational dermal exposure to the resin acids was assessed by tape-stripping the skin of workers involved in the production of wood pellets. The resin acids were analyzed by liquid chromatography mass spectrometry (LC-MS). The limit of detection was 15 pg (7-OXO), 150 pg (DHAA), 285 pg (AA) and 471 pg (PA) per injection. The recovery from spiked tapes was in general 100%. The removal efficiency of the tape was 48-101%. Recovery tests from human skin in vivo showed a mean recovery of 27%. Quantifiable amounts of resin acids were observed on four different skin areas with an increase in exposure during a work shift. This study shows that occupational dermal exposure to resin acids can be assessed by tape-stripping and quantified by LC-MS.     

GC/FTIR-FID测定石化废水中挥发性有机物

所述石化废水中挥发性有机物分析方法 ,以 GC分离 ,FTIR定性 ,FID定量。水样前处理采用大吹脱体积 ,两级捕集的吹脱捕集技术。为解决剖析分析无标样定量问题 ,成功地实现了 GC/FTIR-FID匹配联机 ,使得未知组分定性定量一次完成。方法变异系数低于 5% ,回收率高于 90 % ,最低检出浓度可达 0 .0 0 5mg/L     

Analysis of BTEX and other substituted benzenes in water using headspace SPME-GC-FID: method validation

The analysis of BTEX and other substituted benzenes in water samples using solid phase microextraction (SPME) and quantification by gas chromatography with flame ionization detection (GC-FID) was validated. The best analytical conditions were obtained using PDMS/DVB/CAR fibre using headspace extraction (HS-SPME) at 50 [degree]C for 20 min without stirring. The linear range for each compound by HS-SPME with GC/FID was defined. The detection limits for these compounds obtained with PDMS/DVB/CAR fibre and GC/FID were: benzene (15 ng L(-1)), toluene (160 ng L(-1)), monochlorobenzene (54 ng L(-1)), ethylbenzene (32 ng L(-1)), m-xylene (56 ng L(-1)), p-xylene (69 ng L(-1)), styrene (35 ng L(-1)), o-xylene (42 ng L(-1)), m-dichlorobenzene (180 ng L(-1)), p-dichlorobenzene (230 ng L(-1)), o-dichlorobenzene (250 ng L(-1)) and trichlorobenzene (260 ng L(-1)). This headspace SPME-GC-FID method was compared with a previously validated method of analysis using closed-loop-stripping analysis (CLSA). The headspace SPME-GC-FID method is suitable for monitoring the production and distribution of potable water and was used, in field trials, for the analysis of samples from main intakes of water (surface or underground) and from the water supply system of a large area (Lisbon and neighbouring municipalities).     

The impact of domestic wood burning on personal, indoor and outdoor levels of 1,3-butadiene, benzene, formaldehyde and acetaldehyde

The aim of this study was to quantify personal exposure and indoor levels of the suspected or known carcinogenic compounds 1,3-butadiene, benzene, formaldehyde and acetaldehyde in a small Swedish town where wood burning for space heating is common. Subjects (wood burners, n = 14), living in homes with daily use of wood-burning appliances were compared with referents (n = 10) living in the same residential area. Personal exposure and stationary measurements indoors and at an ambient site were performed with diffusive samplers for 24 h. In addition, 7 day measurements of 1,3-butadiene and benzene were performed inside and outside the homes. Wood burners had significantly higher median personal exposure to 1,3-butadiene (0.18 microg m(-3)) compared with referents (0.12 microg m(-3)), which was also reflected in the indoor levels. Significantly higher indoor levels of benzene were found in the wood-burning homes (3.0 microg m(-3)) compared with the reference homes (1.5 microg m(-3)). With regard to aldehydes, median levels obtained from personal and indoor measurements were similar although the four most extreme acetaldehyde levels were all found in wood burners. High correlations were found between personal and indoor levels for all substances (r(s) > 0.8). In a linear regression model, type of wood-burning appliance, burning time and number of wood replenishments were significant factors for indoor levels of 1,3-butadiene. Domestic wood burning seems to increase personal exposure to 1,3-butadiene as well as indoor levels of 1,3-butadiene and benzene and possibly also acetaldehyde. The cancer risk from these compounds at exposure to wood smoke is, however, estimated to be low in developed countries.     

Analysis of indoor gaseous formic and acetic acid, using radial diffusive samplers

A diffusive sampling method for the determination of gaseous acetic and formic acids, using a radial symmetry diffusive sampler, has been optimised for a 7-day exposure time in this study. Sampling rate determinations were performed on data obtained from a dynamic exposure chamber, simulating the indoor conditions of an empty, closed, room, at room temperature and minimal wind speed. Analysis has been performed by means of ion chromatography. The sampling rates for formic acid concentrations of 128 microg m(-3) and 1248 microg m(-3) were determined to be 91.2 +/- 3.9 ml min(-1) and 111.6 +/- 2.8 ml min(-1), respectively. The acetic acid sampling rate was independent of the concentration in the range 160 microg m(-3)-1564 microg m(-3), and amounted to 97.3 +/- 3.1 ml min(-1). Experimentally determined sampling rates showed deviations of 3% for acetic acid, and 3-21% for formic acid, in relation to theoretically derived values. The blank values were as low as 1.69 +/- 0.07 microg for formic acid and 1.21 +/- 0.14 microg for acetic acid, and detection limits lower than 0.5 microg m(-3) could be achieved, which is an improvement of 98-99% compared to previously validated diffusive sampling methods. This study describes the first step of an extended validation program in which the applicability of these types of samplers for the measurement of organic acids will be validated and optimised for the environmental conditions typical for museum showcases.     

Occurrence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Lake Maggiore (Italy and Switzerland)

Samples of air (gas and particulate phases), bulk deposition, aquatic settling material and sediments were collected in Lake Maggiore (LM) in order to determine their content of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Air (gas and particulate phases) concentrations were 0.5 pg m(-3), 80 pg m(-3), 13 pg m(-3) and 106 pg m(-3) for SigmaPCDD/Fs, SigmaPCBs, Sigma dioxin-like PCBs (DL-PCBs) and SigmaPBDEs, respectively. Deposition fluxes ranged from 0.7 ng m(-2) d(-1) for SigmaPCDD/Fs to 32 ng m(-2) d(-1) for SigmaPCBs. Aquatic settling material presented concentrations of 0.4 ng g(-1) dry weight (dw) for SigmaPCDD/Fs, 13 ng g(-1) dw for SigmaPCB, 3.4 ng g(-1) dw for SigmaDL-PCBs and 5.7 ng g(-1) dw for SigmaPBDEs. Mean sediment concentrations were 0.4 ng g(-1) dw for SigmaPCDD/Fs, 11 ng g(-1) dw for SigmaPCB, 3 ng g(-1) dw for SigmaDL-PCBs and 5.1 ng g(-1) dw for SigmaPBDEs. Similar PCDD/F and DL-PCB congener patterns in all the environmental compartments of LM point to an important, if not dominant, contribution of atmospheric deposition as source of these pollutants into LM. In contrast, PBDE congener distribution was not similar in the different environmental compartments. BDE 47 dominated air and settling material, while BDE 209 was the predominant congener in the bulk atmospheric deposition. Moreover, sediments showed two distinct PBDE congener profiles. Lower PBDE concentrated sediments were dominated by congeners 47 and 99, while BDE 209 dominated in higher PBDE concentrated samples. This suggests the influence of local sources as well as atmospheric input of PBDEs into LM.     

水中酞酸酯类化合物的测定

通过筛选水中酞酸酯类化合物的萃取条件，优选出方法简单、回收率高的萃取方法，利用GC—FID和GC—MS—SIM检测，证明筛选的方法稳定可靠，平均回收率在98．1％～105％，在能力验证中获得了满意的结果。     

Concentration, distribution and source apportionment of atmospheric polycyclic aromatic hydrocarbons in the southeast suburb of Beijing, China

Total suspended particle samples and gas phase samples were collected at three representative sampling sites in the southeastern suburb of Beijing from March 2005 to January 2006. The samples were analyzed for 16 US EPA priority PAHs using GC/MS. Concentrations of Sigma PAHs in particle and gas phases were 0.21-1.18 x 10(3) ng m(-3) and 9.5 x 10(2) ng-1.03 x 10(5) ng m(-3), respectively. PAH concentrations displayed seasonal variation in the order of winter>spring>autumn>summer for particle phase, and winter>autumn>summer>spring for gas phase. Partial correlation analysis indicates that PAH concentrations in particle phase are negatively correlated with temperature and positively correlated with air pollution index of SO(2). No significant correlation is observed between gas phase PAHs and the auxiliary parameters. Sources of PAH are identified through principal component analysis, and source contributions are estimated through multiple linear regression. Major sources of atmospheric PAHs in the study area include coal combustion, coke industry, vehicular emission and natural gas combustion.     

SBSE-GC/MS法测定饮用水源水中7种多氯联苯单体

采用搅拌棒吸收萃取(SBSE)-溶剂解吸-气相色谱/质谱联用法测定饮用水源水中7种多氯联苯单体,优化了萃取和解吸条件。方法在5 ng/L~100 ng/L范围内线性良好(r≥0.979),7种多氯联苯单体的检出限为0.8 ng/L~3.4 ng/L(100 mL水样SBSE萃取2 h),加标10 ng/L时实际水样回收率为93.0%~116%。     

Spatial and temporal distribution of gaseous elemental mercury in Chongqing, China

In order to investigate the spatial and temporal variability of atmospheric mercury (Hg) in Chongqing, China, gaseous elemental mercury (GEM) was measured from August 2006 to September 2007, using Lumex multifunctional mercury analyzer RA-915(+) (Lumex Ltd., Russia). The mean GEM concentration was 6.74 +/- 0.37 ng m(-3) in Chongqing, much higher than the accepted global background values (1.5-2 ng m(-3)). The GEM concentrations were different in different function areas. GEM in transport, industrial and commercial areas were 7.07 +/- 1.04, 7.05 +/- 0.96 and 6.71 +/- 1.10 ng m(-3), respectively, while GEM was 6.14 +/- 1.30 and 4.32 +/- 1.04 in the educational/recreational and nature conservation areas, suggesting that Hg emissions from mobile vehicles and industrial sources (specially coal combustion) were the most important contributors to atmospheric Hg in Chongqing. Mean Hg concentrations also had monthly variations with highest in November (8.24 +/- 0.50 ng m(-3)) and lowest values in August (5.36 +/- 0.70 ng m(-3)). Additionally, the diurnal variation of GEM concentrations was dependent on the local/regional atmospheric conditions. At Jinyun Mountain site (natural conservation area), hourly GEM concentrations had much higher values in daytime than at night. At Power Plant site, however, the hourly GEM concentrations were lower in daytime than at night. GEM concentrations in the air were correlated significantly with meteorological parameters except for barometric pressure.     

Use of denuder/filter apparatus to investigate terpene ozonolysis

A denuder/filter apparatus was used to collect the gaseous and particulate reaction products from ozonlysis of α-pinene, limonene and α-terpineol in an effort to develop sampling techniques for characterizing indoor environment chemistry. Carboxylic acids found in the particulate phase were derivatized to 2,2,2-trifuoroethylamides by reaction with 3-ethyl-1-[3-(dimethylamino)propyl]carbodiimide hydrochloride (EDC) and 2,2,2-trifluoroethylamine hydrochloride (TFEA). Carbonyl compounds collected in both gas phase and particulate phase were derivatized to their respective oximes by reaction with O-(2,3,4,5,6-pentafluoro-benzyl)hydroxylamine hydrochloride (PFBHA). The ozonolysis of α-pinene yielded the carboxylic acids: cis-pinonic acid and pinic acid and the proposed carboxylic acids methanetricarboxylic acid and terpenylic acid; the carbonyls: 4-oxopentanal, norpinonaldehyde, pinon aldehyde and the proposed carbonyl methylidenepropanedial. The ozonolysis of limonene yielded the carboxylic acids: limonic acid and pinic acid and the carbonyls: 1-(4-methylcyclohex-3-en-1-yl)ethanone (4AMCH), glyoxal, methyl glyoxal, 4-oxopentanal and 6-oxo-3-(prop-1-en-2-yl)heptanal (IPOH). The ozonolysis of α-terpineol yielded the proposed carboxylic acids: terpenylic acid and homoterpenylic acid and the carbonyls: (5E)-6-hydroxyhept-5-en-2-one, methyl glyoxal and 4-oxopentanal.     

甲胺、二甲胺及三甲胺的气相色谱测定

采用气相色谱法、大口径毛细管柱分离了甲胺、二甲胺、三甲胺.用氮磷检测器(NPD)检测,得到了良好的分离效果和很高的灵敏度,检测限可达0.025mg/L.同时,对甲胺类在NPD和氢火焰离子化检测器(FID)上的灵敏度作了比较,发现甲胺类物质在NPD上的灵敏度大大高于FID,因此,前者特别适用于检测环境试样中低含量甲胺类有机物的监测.     

Aerosol chemical characteristics of an island site in the Bay of Bengal (Bhola-Bangladesh)

Aerosol constituents (elemental carbon, organic carbon, soluble ions including organic acids, and selected trace metals) were investigated from samples of a field campaign taking place at Bhola Island in the Bay of Bengal (Bangladesh). The campaign took place in the pre-monsoon season (May 2001) using low volume samplers. Carbonaceous material comprised the majority of the analysed components. The average concentrations of EC and OC were 2.8 and 4.6 microg m(-3), respectively. Oxalic acid was the most abundant dicarboxylic acid (average 268 ng m(-3)) followed by malonic and malic acid. The contribution of carboxylic acids-carbon to organic carbon was 2.0%. Average concentrations observed for sulfate and nitrate were 3.7 microg m(-3) and 1.5 microg m(-3). Two different types of aerosol were identified at the rural background site on Bhola Island during southerly synoptic flow by means of trajectory analysis: air masses were transported from the Bay of Bengal to the sampling site in all cases. However, during "Period 1" they experienced longer residence times over the Indian Ocean, while the "Period 2" trajectories came along the Indian coast or passed over the Indian continent. During Period 1 the concentration levels of soluble ions were a factor of 4-6 lower than during Period 2. The concentrations of EC, OC and K differed less than a factor of 1.5 between the two periods. The Period 1 aerosol showed similarities to the haze layers observed during winter-monsoon conditions south of India during the INDOEX experiment. Based on EC/TC and K/EC ratios we find that around 80% of the carbonaceous aerosol from Period 1 in Bhola is from fossil fuel and only around 50% from Period 2. Absolute concentrations of carbonaceous species, soluble ions and trace metals indicate that the background site on Bhola Island is affected by emissions from urbanized regions of Southeast Asia.     

大气预浓缩仪-GC/FPD测定环境空气中的痕量硫化物

采用大气预浓缩仪-GC/FPD建立了环境空气中7种含硫化合物的测定方法。结果表明,经惰性化改造后的大气预浓缩仪-GC/FPD测定系统的基线低,对硫化物无残留。7种化合物的线性回归方程的相关系数均在0.995以上,高、中、低3种浓度的空白加标回收率分别为98.6%~105.3%、99.1%~103.7%、85.7%~99.7%,除硫化氢的相对标准偏差为10.9%外,其余6种含硫化合物的相对标准偏差可控制在6.9%以内。当进样体积为400 m L时,方法的检出限在0.10~1.1 ng/m3。CO2、H2O对实际样品的测定无干扰。因此,该方法能够满足目前监测工作的要求,更加适用于环境空气中痕量含硫化合物的测定。     

Airborne endotoxin in woodworking (joinery) shops

Symptoms such as shortness of breath and cough have been noted in woodworking facilities even where wood dust itself is well-controlled. Suspicion has fallen on other possible contaminants in the workplace atmosphere, including bacterial endotoxin. A few studies have indicated potentially high endotoxin exposure with exposure to fresh wood in sawmills and in the production of fiberboard and chipboard, but fewer studies have been carried out on exposure to endotoxin in dry wood work, for example in joineries. A study of the endotoxin content of airborne wood dust samples from US woodworking facilities is presented, from the re-analysis of samples which previously had been taken to establish mass collection relationships between the IOM sampler, the closed-face 37 mm plastic cassette (CFC) sampler and the Button sampler. Endotoxin was strongly correlated with total dust, but the endotoxin content of a few fresh wood samples was found to be up to ten times higher per unit of wood dust than for dried-wood samples, and this difference was significant. No long-term time-weighted average sample exceeded the recommended limit value of 50 EU m(-3) (EU, endotoxin units)used in the Netherlands, although a number of the IOM samples came close (seven samples or 44% exceeded 20 EU m(-3)) and one short-term (48 minute) sample registered a high value of 73 EU m(-3). The geometric mean concentration from the IOM samples (11 EU m(-3)) is within the range of geometric means found from Australian joineries (3.7-60, combined: 24 EU m(-3)). In contrast, the corresponding values from the CFC (3.6 EU m(-3)), and the Button sampler (2.1 EU m(-3)) were much lower and no samples exceeded 20 EU m(-3). Endotoxin is likely only to be a significant problem in working with dried woods when associated with very high dust levels, where the wood dust itself is likely to be a cause for concern. The results from the few samples in this study where fresh wood was being worked were similar to results from other studies involving fresh woods. The agreement between these studies is encouraging given the difficulties of endotoxin analysis and the wide variation often expected between different laboratories.     

中国表层水体沉积物中多环芳烃源解析及评价

采用索氏提取气相色谱-质谱法测定中国6个重点水体表层沉积物中16种多环芳烃的含量。各化合物含量范围分别为长江6.20~163 ng/g、淮河7.90~249 ng/g、海河12.1~401 ng/g、松花江5.75~152 ng/g、太湖29.1~2 810 ng/g和滇池19.1~795ng/g；16种多环芳烃的总量分别为：长江1 147 ng/g、淮河1 723 ng/g、海河2 595 ng/g、松花江793 ng/g、太湖12472 ng/g、滇池3 714 ng/g，属中等污染水平。利用特征分子比值法分析结果表明6条水体表层沉积物中PAHs均可能以燃料（包括柴油、汽油、煤、木材）燃烧以及焦化污染为主。淮河和滇池还可能存在轻微石油泄漏污染。利用沉积物质量基准法（SQGs）和沉积物质量标准法分别对6条水体表层沉积物中多环芳烃的风险评估表明严重的多环芳烃生态风险在这些水体表层沉积物中不存在，但长江、淮河、松花江、海河均可能存在一定的潜在风险，负面生物毒性效应会偶尔发生，风险主要来源于荧蒽和菲。太湖和滇池水体中存在的潜在多环芳烃风险种类较多，风险主要来源于菲、荧蒽、芘、苯并（a）蒽、苊和蒽，对水生生物毒性效应较高，有必要进行更深入细致的调查研究高风险区域底栖生物的受损状况、污染来源和途径，以制定合理的污染控制对策。     

气相色谱-质谱法测定大气中98种挥发性有机物

通过色谱-质谱联用法(简称GC-MS),利用低温冷阱技术对大气中的VOCs进行浓缩富集,然后经过加热解吸分别至毛细管色谱柱和FID检测器及MS检测器,对大气中98种挥发性有机化合物(VOCs)进行分离、定性、定量测定。方法检出限为0.008×10-9~0.100×10-9(V/V);线性相关系数的平方值为0.992 7~1,相对标准偏差为4.0%~20.2%,总体标准偏差为0.154 2~0.952 1。     

Ambient elemental, reactive gaseous, and particle-bound mercury concentrations in New Jersey, U.S.: measurements and associations with wind direction

Two and a half years of data of ambient concentrations of elemental mercury (Hg(0)), reactive gaseous mercury (RGM), and particle-bound mercury (Hg(p)) were collected at measurement sites at Elizabeth, New Jersey and New Brunswick, New Jersey with Tekran sampling units. The data were processed, summarized, and analyzed from a variety of perspectives. Data quality control and quality assurance procedures are described. Wind direction and wind speed data for each of the sites were also collected. Significant temporal variations in concentrations of all three species were observed. Some significant directional variations were also seen. The sporadic nature of many of the temporal variations is consistent with and could reflect highly variable emissions patterns from anthropogenic mercury sources. Overall mean concentrations of all species were determined. These were, for Hg(0), Hg(p), and RGM respectively; 2.25 +/- 0.04 nanograms per cubic meter (ng/m(3)), 8.21 +/- 0.39 picograms per cubic meter (pg/m(3)), and 8.93 +/- 0.31 pg/m(3) (arithmetic means and 95% confidence intervals) at Elizabeth, and 2.15 +/- 0.02 ng/m(3), 10.73 +/- 0.45 pg/m(3), and 6.04 +/- 0.30 pg/m(3) at New Brunswick. Mean concentrations were determined for 16 different sectors representing wind directions. The impact of one known large source is suggested by these data. Reasons for some directional variations are not apparent and suggest a need for further investigation.     

Polycyclic aromatic hydrocarbons study and toxic equivalency factor (TEFs) in Tehran, IRAN

Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants released by various urban combustion sources. Benzo[a]pyrene (BaP) is a representative member of the class of PAHs. Health risk assessment associated with inhalatory PAHs uptake is often estimated on the basis of the BaP concentrations in air. Atmospheric particulate PAHs concentrations were measured at five locations in Tehran, Iran. Sixteen PAHs were extracted from the airborne particles and analyzed by HPLC. Total PAHs concentrations (16 compounds) at five station Arjanteen, Enghelab, Azadi, Bahman, Haft Houz were respectively, 70.2, 96.5, 130, 79.1, 44.1 ng/m(3). The information obtain from the present study indicated that mean of human carcinogens are: benzo[a]antheracene (0.17-4.76 ng/m(3)), chrysene (1.74-3.62 ng/m(3)), benzo[b]fluoranthene (0-5.25 ng/m(3)), benzo[k]fluoranthene (0.32-1.72 ng/m(3)), benzo[a]pyrene (1.41-3.82 ng/m(3)), dibenzo[a,h]anthracene (0.33-2.13 ng/m(3)), and indeno[1,2,3-cd]pyrene (0.25-11.08 ng/m(3)). The development and the establishment of a toxicity equivalency factor (TEF) are used in the assessment of mixtures containing PAHs. The contribution of the carcinogenic potency of BaP alone is in the range of 49.6-76.3% of the total carcinogenic activity. The annual number of lung cancer cases (persons per million) among Tehran residents (population = 10 millions) attributable to these carcinogenic PAHs compounds in 2005 was estimated at 58 persons per million. In Tehran urban areas vehicular emission are the primary contributor to PAHs concentrations, with additional local contributors like industrials emissions.     

Organophosphorus flame retardants and plasticizers in air from various indoor environments

Eleven organophosphorus compounds (OPs) that are used as plasticizers and flame retardants were analysed in duplicate samples of indoor air from 17 domestic and occupational environments. Solid-phase extraction (SPE) columns were used as adsorbents and analysis was performed using GC with a nitrogen phosphorus selective detector. The total amounts of OPs in the air samples ranged between 36 and 950 ng m(-3); tris(chloropropyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) being the most abundant (0.4 to 730 ng m(-3)), followed by tributyl phosphate (0.5-120 ng m(-3)). Public buildings tended to have about 3-4 times higher levels of OPs than domestic buildings. The relative amounts of individual OPs varied between the sites and generally reflected the building materials, furniture and consumer products used in the sampled environments. Potential sources of these compounds include, inter alia, acoustic ceilings, upholstered furniture, wall coverings, floor polish and polyvinylchloride floor coverings. A correlation was observed between the TCEP concentrations in the air in the sampled environments and previously reported concentrations in dust, but no such correlation was seen for the heavier and less volatile tris(2-butoxyethyl) phosphate (TBEP). Based on estimated amounts of indoor air inhaled and dust ingested, adults and children in the sampled environments would be exposed to up to 5.8 microg kg(-1) day(-1) and 57 microg kg(-1) day(-1) total OPs, respectively.