Cooking Operations Research Articles

Reduction of PDO Pecorino Siciliano cheese making duration: Microbial dynamics and quality attributes deriving from replacing whey permeate with hot water during cooking

This work was carried out with the aim to reduce the transformation duration of Protected Designation of Origin (PDO) Pecorino Siciliano cheese. To this purpose, the cooking in hot water (experimental production, EXP) was compared to the traditional cheese cooking under whey permeate (control production, CTR). The microbiological composition of under rind (UR) and core (Co) section of CTR and EXP cheeses was determined by a combined culture-dependent and -independent approach. Total mesophilic microorganisms and lactic acid bacteria (LAB) present in raw ewes' milk (5.0 log CFU/mL) increased during cheese making and reached values of about 8.0 log CFU/g in both sections (UR and Co) of 5-month ripened cheeses of both productions (CTR and EXP) monitored. The identification of the viable LAB populations in ripened cheeses showed that Enterococcus, Lacticaseibacillus, Lactiplantibacillus, Levilactobacillus, Limosilactobacillus and Streptococcus dominated UR and Co sections of all cheeses. MiSeq Illumina analysis demonstrated that LAB populations (lactobacilli, lactococci and streptococci) dominated the bacterial community of cheeses at 95.63–98.41 % of relative abundance. The two different cooking operations did not influence the physicochemical characteristics of PDO Pecorino Siciliano cheeses. Sensory evaluation performed by artificial senses analysis and trained panelists confirmed that the modification of PDO Pecorino Siciliano cheese production protocol did not significantly affect product characteristics and overall acceptance. Thus, data of this work confirmed that cooking under hot water allowed to reduce transformation duration and safeguard typicality of PDO Pecorino Siciliano cheese.

URBAN KITCHEN: A FORM OF URBAN SYSTEM BASED ON COLLECTIVE OPERATION

This paper aims to explore various spatial strategies in urban operations, particularly operation of collective kitchen as a form of the urban system. Through the tracing of micro spatial practice, this paper expands the idea of domestic in urban design discourse. This paper uses a case study method to investigate urban kitchen system in Kampung Bustaman, Semarang, Indonesia, where cooking operations are part of everyday life that is carried out collectively. It shows that the kampung’s everyday operations generate the system of an urban kitchen, where domestic activities shift from the household to become integrated into society, challenging the dualities between domestic and urban space. The mapping of the everyday operations reveals hidden systems of society where connectivity and spatial negotiations play important role. This paper introduces the idea of the urban kitchen as a form of urban system that is transformative, dynamic, and flexible that is driven by collective domestic operations.

Effects of combined roasting and steam cooking on NaCl reduction and quality changes in marinated salmon flesh as compared with roasting and water bath cooking

In this study, combining roasting with steam cooking was proposed to reduce sodium chloride (NaCl) content during cooking operations. The NaCl reduction effects of roasting-steam cooking (RS), roasting (R), and water bath cooking (WB) on marinated salmon flesh samples with different cooking times (2, 4, 6 and 8 min) were evaluated. Results showed that the NaCl contents in the samples treated by RS and R were reduced by 22.44% and 15.59%, respectively. RS could also provide high overall acceptability without compromising the taste and flavour. FTIR analysis demonstrated that RS and R increased α-helix and β-sheet and slightly decreased β-turn in sample proteins as compared with WB, indicating that RS could achieve low denaturation and weak unfolding degree of protein structure due to protein conformation inhibited by the steam. Therefore, RS could serve as a novel method for reducing NaCl contents in cooked meat products.

A Study on the Distribution Characteristics of Formaldehyde, Volatile Organic Compounds, Particulate Matter, and Airborne Bacteria in Indoor Play Centers

This study aimed to evaluate the indoor air quality differences at 19 indoor play centers of cafés and play areas in Gyeonggi-do where were 430 m<sup>2</sup> or larger. We examined concentrations of formaldehyde (HCHO), volatile organic compounds (VOC), particulate matter, and total airborne bacteria, and how their distributions varied with the number of visitors at the places. On weekdays, there were no statistically significant differences in mean indoor air pollutant concentrations between the cafés and play areas at 95% confidence intervals. However, significant differences were observed on weekends when the number of visitors increased. HCHO concentrations increased up to 159%, and VOC concentrations increased up to 210%. A higher increase rate of HCHO occurred at the cafés compared to the play areas since cooking operations were performed under natural ventilation. The PM10 concentration increased by approximately 33.2%, with an increase of 49.2% in the play areas and a 18.3% increase in the cafés on weekends. PM<sub>2.5</sub> concentration particularly increased during weekends in the cafés and play areas by 113% and 63.6%, respectively. During cooking operations, the concentration of gaseous and particulate pollution increased more in the air pollutant concentration of cafés, and the overall bacterial concentration increased during weekends due to higher numbers of visitors. Therefore, indoor play centers with cooking operations require adequate air quality management to mitigate the indoor pollution.

Enhancement of vitamin D2 in edible mushroom using ultraviolet irradiation and assessing its storage and cooking stability

Purpose The purpose of this study was to optimize the parameters for enhancing the vitamin D2 formation in three edible mushroom varieties, namely, shiitake mushroom (Lentinula edodes), white button mushroom (Agaricus bisporus) and oyster mushroom (Pleurotus ostreatus) using ultraviolet (UV) irradiation. Design/methodology/approach Freshly harvested mushrooms were irradiated with UV-B and UV-C lamps. Further, mushrooms were treated with UV-B at a distance ranging between 10 and 50 cm from the UV light source, for 15–150 min, to maximize the conversion of ergosterol to vitamin D2. Analysis of vitamin D2 content in mushrooms before and after UV exposure was done by high pressure liquid chromatography (HPLC). Findings HPLC results showed a significant (p < 0.001) increase in vitamin D2 levels of shiitake (17.3 ± 0.35 µg/g), button (24.9 ± 0.71 µg/g) and oyster (19.1 ± 0.35 µg/g) mushrooms, irradiated with UV-B at a distance of 20–30 cm for 120 min. Further, stability studies revealed that vitamin D2 levels in UV-B-irradiated mushrooms gradually increased for 48 and 72 h of storage at room and refrigeration temperatures, respectively. During cooking operations, 62%–93% of vitamin D2 was retained in UV-B-irradiated mushrooms. Originality/value This study describes the most effective parameters such as ideal wavelength, mushrooms size, duration of exposure and distance from UV sources for maximum vitamin D2 formation in edible mushrooms using UV irradiation. Further, assessment of vitamin D2 stability in UV exposed mushrooms during storage period and cooking operations has been carried out. In addition, this study also provides a comparison of the vitamin D2 levels of the three widely cultivated and consumed mushroom varieties treated simultaneously under similar UV exposure conditions.

Determination and Similarity Analysis of PM2.5 Emission Source Profiles Based on Organic Markers for Monterrey, Mexico

Source attribution of airborne particulate matter (PM) relies on a host of different chemical species. Organic molecular markers are a set of particularly useful marker compounds for estimating source contributions to the fine PM fraction (i.e., PM2.5). Although there are many source apportionment studies based on organic markers, these studies heavily rely on the few studies that report region-specific emission profiles. Source attribution efforts, particularly those conducted in countries with emerging economies, benefit from ad hoc information to conduct the corresponding analyses. In this study, we report organic molecular marker source profiles for PM2.5 emitted from 12 major sources types from five general source categories (meat cooking operations, vehicle exhausts, industries, biomass and trash burning, and urban background) for the Monterrey Metropolitan Area (Mexico). Source emission samples were obtained from a ground-based source-dominated sampling approach. Filter-based instruments were utilized, and the loaded filters were chemically characterized for organic markers by GC-MS. Levoglucosan and cholesterol dominate charbroiled-cooking operation sources while methoxyphenols, PAHs and hopanes dominate open-waste burning, vehicle exhaust and industrial emissions, respectively. A statistical analysis showed values of the Pearson distance < 0.4 and the similarity identity distance > 0.8 in all cases, indicating dissimilar source profiles. This was supported by the coefficient of divergence average values that ranged from 0.62 to 0.72. These profiles could further be utilized in receptor models to conduct source apportionment in regions with similar characteristics and can also be used to develop air pollution abatement strategies.

Development of a thermal storage type solar cooker for high temperature cooking using solar salt

High temperature cooking operations like frying, roasting and baking using solar energy are normally carried out at the focus of parabolic dish concentrators. This leads to heat discomfort, risk of burns or eye damage to the user. A device which stores latent heat in a phase changing eutectic mixture called “solar salt” was designed and tested, which would enable its storage in an insulated container, and cooking in the shade of a kitchen when needed. It was able to successfully store heat at its melting point of 220 °C in a charging time of 110 min. Frying temperature of 170 – 180 °C for the oil was easily obtained during indoor cooking and 0.25 kg of potato chips were fried in 17 min from one charge of heat, while a total of about 0.6 kg of rice was cooked in two successive batches from one charge, taking 20 min each.

Bulgur cooking process: Recovery of energy and wastewater

The cooking process in the grain industries (bulgur, parboiled rice, wheat, pulses, etc.) is an important operation, which requires high levels of energy and water. The wastewater from the cooking process in the bulgur industry is discharged without any recovery measures. In this study, the recovery of energy and water from the wastewater of the bulgur cooking process was investigated, including; i) recovery of the wastewater from the initial cooking process using filtration, centrifugation, a packed-filtering column (containing sand, activated carbon and resin) and ultraviolet-light (UV), and ii) the re-use in the subsequent cooking process by mixing with fresh water. Dissolved Oxygen (DO), 5 days-Biochemical Oxygen Demand (BOD5), pH, turbidity, conductivity, total solid content and Brix were measured to determine the effects of the wastewater treatment operations. It was found that these treatments were significantly (P ≤ 0.05) effective in the reduction of the BOD5 values from 429.5 to 93.7 mg/L. The total solid content, Brix, conductivity and turbidity values decreased. The energy requirement to heat up the water for cooking may be reduced to 57% of current energy usage. It was found that the re-use of wastewater may be possible for the subsequent cooking operations.

Havells India Ltd: QRG foundation on the cross road

Learning outcomes The case will help students to understand the challenges faced by the organisations with respect to implementing social reforms; develop an understanding in creating sustainable solutions to the social problems; identify leadership challenges faced by such enterprises; and understand grassroots challenges of establishing such enterprises in India. Case overview The case deals with the dilemma and challenges of Col. Nirban Singh, in-charge of Midday meal of QRG Foundation at Alwar. The foundation was based on the vision of creating a positive impact in communities through social service. They follow a socially positive agenda and work consistently to contribute to the betterment of the society and its future. Their initiatives revolve around their concerns for the nutrition, health and education of children. It was decided that out of the three programmes on environment, sanitation and the mid-day meal (MDM) for school going children, the later will be the flagship CSR activity of Havells. The programme began with coverage of 1,500 students in 2005. In 2015, ten years since inception, the Havells MDM scheme catered to over 58,000 students from 688 schools every day in the Alwar region of Rajasthan. Till February 2017, Havells has served over 66 million meals to students and impacted lives of millions of Children (Source: Havells). The case illustrates innovative model of automation in food preparation and cooking operations adopted by the company with minimum human intervention, to maintain hygiene and thereby with the help of special vans owned by the company quickly distribute freshly cooked food to schools at lunch time. The case highlights the purpose behind this initiative, challenges that company face in day-to-day activities and the impact of this initiative on the children in Alwar district at Rajasthan. QRG is at the crossroad: Col. Nirban must identify the way forward without compromising on the quality of the services provided. His available options are replicate the programme in the new state, upscale their services in Rajasthan and focus on the existing project and work on the ways to make it sustainable. Complexity academic level The case can be used in both undergraduate and graduate levels in entrepreneurship, management and leadership classes to discuss corporate social responsibility, social entrepreneurship, NGO and responsible business. The case provides practical challenges faced by the social enterprises/NGOs in running the programme, implementing the policies on the ground, replicating and sustaining it. The case can be used in strategy, innovation and ethic classes. Supplementary materials Teaching Notes are available for educators only. Please contact your library to gain login details or email support@emeraldinsight.com to request teaching notes. Subject code Management science.

Multiproduct Traditional Japanese Cuisine Restaurant Improves Labor Productivity by Changing Cooking Processes According to Service Product Characteristics

This study introduces three cooking process improvements for a multiproduct traditional Japanese cuisine restaurant to improve labor productivity and to assess relations between offered process changes and service product characteristics. Restaurant productivity is the lowest among service industries because restaurants are labor-intensive. Therefore, the industry is affected by service product characteristics. Combining line and cell cooking systems, batch cooking using partial freezers, and combining built-to-order and built-to-plan cooking are introduced into actual multiproduct traditional Japanese cuisine restaurants to change cooking operations and improve labor productivity. Results show that all cooking process changes reduce work hours. The correlation coefficient between work hour and sales revenue improved by line and cell cooking, but it is degraded by batch cooking and built-to-order and built-to-plan cooking. Line and cell cooking enhance simultaneity and reduce the influence of perishability because the system adopts hourly work hours to fluctuation of hourly sales by changing cooking systems (line/cell). However, the system does not resolve heterogeneity and intangibility difficulties because the system is intended to resolve quantitative difficulties of cooking operation systems. Batch cooking systems reduce the influence of simultaneity and perishability of service products because the method reduces cooking frequency using partial freezers. Furthermore, the system improves heterogeneity because the restaurant can provide head-chef-made dishes even if the chef is not working at the restaurant. However, the system does not resolve difficulties of intangibility because the system is not designed to improve customers’ subjective evaluation for service. Built-to-order and built-to-plan cooking reduce the respective influences of simultaneity, perishability, and heterogeneity of service products to some degree because built to plan teams also practice batch cooking using partial freezers. However, the system does not resolve the difficulty of intangibility because the system is not intended to improve customers’ subjective evaluation for service.

Mental representation of domestic cooking operations among Japanese consumers

Cooking is a daily undertaking that ensures the proper ingestion of food. However, mental representations of home cooking have yet to be quantitatively elucidated. The primary purpose of the series of three studies presented here was to quantitatively describe the conceptualization of cooking among Japanese consumers by employing Internet surveys. The first study extracted superordinate categories of cooking-related operations, (1) core cooking, (2) subsidiary cooking and (3) convenience food preparation, for 100 Japanese consumers by utilizing an exploratory factor analysis of 30 presumably cooking-related operations. The second study made further sub-categorizations within each superordinate category by utilizing hierarchical cluster analyses in 500 newly recruited Japanese consumers. Core cooking was sub-categorized into “to pickle”, “to cut and heat”, “to season”, and “to mix”. Subsidiary cooking was sub-categorized into “to preserve”, “to acquire”, and “to arrange”. Convenience food preparation was not further sub-categorized. In Study 3, based on the fit indices obtained from structural equation modeling, the appropriateness of the categorizations and sub-categorizations of Studies 1 and 2 was confirmed using 500 newly recruited Japanese consumers. Thus, the current study is the first to quantitatively examine the conceptualization of cooking by elucidating the relationships among a variety of cooking-related operations.

Differences in the Characteristics of Cooking Operations and Procedures between Novices and Experts

Differences in the Characteristics of Cooking Operations and Procedures between Novices and Experts

COOKING TECHNOLOGIES

Most foods are cooked by transferring heat from a heating medium or a heated surface to the food by conduction, convection, or radiation. Other techniques rely on the development of heat inside the solid by the application of electric fields, electromagnetic waves, or high pressure, such as in the case of extrusion. Most technologies can be used as one-step cooking operations; or it is not uncommon to have a combined operation to take advantage of the strengths of different technologies. This chapter presents an overview of cooking technologies by application of heat, which is performed on foods to improve their eating quality and nutritional value.

Portable, Ambient PM2.5 Sensor for Human and/or Animal Exposure Studies

ABSTRACTA field-portable device for logging PM2.5 mass concentration data has been developed. The device combines the Arduino microprocessor with an SD card, a Sharp DN7C3CA006 optical dust monitor, and 10,000-mAh battery. The dust sensor uses a virtual impactor to size select particles <2.5 microns prior to illuminating the selected fraction with an LED. The LED is triggered by a circuit controlled with the Arduino. Nephelometric detection at 120° referenced to incidence is used. The voltage signal reported by the dust sensor is converted to PM2.5 mass through calibration onboard the Arduino. Data points can be saved to the SD card as rapidly as 0.3 s, although averaging signals over 60 s produced more optimal detection limits. For a 60 s average, the PM2.5 mass limit of detection was 9 µg m−3, indicating that the sensor will be useful for monitoring human exposure to fine particles. Portable exposure monitoring has been demonstrated with the sensing platform as several individuals carried the device with them during daily activities in Lubbock, TX and Atlanta, GA. For this group of test subjects, values of PM2.5 exposure varied from 0 to 1000 µg m−3 during the sampling periods. It was observed that, by far, the highest levels of PM2.5 occur during periods of cooking, or being near cooking operations. Other periods of high PM2.5 occurred during ground transportation, use of personal care products, vacuuming, and visiting restrooms. When hourly personal exposure data were correlated with hourly average PM2.5 for outdoor air for the Atlanta data set, a very weak correlation was found (R2 = 0.026). Only two out of eight sampling periods did the personal monitoring estimate of exposure agree with that predicted by outdoor monitoring to within 15%. Personal exposure was often affected by circumstantial, short-term, high exposure events that are difficult to model or predict effectively. The short-term exposure events generally cause true exposure to be higher than that predicted by using outdoor ambient PM2.5 to generate estimates. This finding complicates interpretation of epidemiological studies that find links between ambient outdoor PM2.5 levels and human health, while it buttresses the case for using personal ambient monitors.

立体高次局所自己相関（CHLAC）特徴量を用いた線形判別法による調理動作の識別に関する基礎研究

Recently, robotic cooking support systems that help human's cooking operations have been developed. However, since these systems usually need many sensors to recognize human's cooking operations, it is difficult to introduce these system in a ordinary kitchen. In this study, we use CHLAC(Cubic Higher-order Local Auto-Collelation) features to recognize human's cooking operations. Further, Fisher linear discriminant is used to map the CHLAC feature space into the low dimension space, and the results verified the validity of the proposed approach.

Chemical mass balance source apportionment of fine and PM&lt;sub&gt;10&lt;/sub&gt; in the Desert Southwest, USA

The Desert Southwest Coarse Particulate Matter Study was undertaken in Pinal County, Arizona, to better understand the origin and impact of sources of fine and coarse particulate matter (PM) in rural, arid regions of the U.S. southwestern desert. The desert southwest experiences some of the highest PM10 mass concentrations in the country. To augment previously reported results, 6-week aggregated organic speciation data that included ambient concentrations of n-alkanes, polycyclic aromatic hydrocarbons, organic acids, and saccharides were used in chemical mass balance modeling (CMB). A set of re-suspended soil samples were analyzed for specific marker species to provide locally-appropriate source profiles for the CMB analysis. These profiles, as well as previously collected plant and fungal spore profiles from the region, were combined with published source profiles for other relevant sources and used in the CMB analysis. The six new region-specific source profiles included both organic and inorganic species for four crustal material sources, one plant detritus source, and one fungal spore source. Results indicate that up to half of the ambient PM2.5 was apportioned to motor vehicles with the highest regional contribution observed in the small urban center of Casa Grande. Daily levels of apportioned crustal material accounted for up to 50% of PM2.5 mass with the highest contributions observed at the sites closest to active agricultural areas. Apportioned secondary PM, biomass burning, and road dust typically contributed less than 35% as a group to the apportioned PM2.5 mass. Crustal material was the primary source apportioned to PM10 and accounted for between 50–90% of the apportioned mass. Of the other sources apportioned to PM10, motor vehicles and road dust were the largest contributors at the urban and one of the rural sites, whereas road dust and meat cooking operations were the largest contributors at the other rural site.

Behavior of Staphylococcus aureus in Culture Broth, in Raw and Thermized Milk, and during Processing and Storage of Traditional Greek Graviera Cheese in the Presence or Absence of Lactococcus lactis subsp. cremoris M104, a Wild, Novel Nisin A–Producing Raw Milk Isolate

This study was conducted to evaluate the behavior of Staphylococcus aureus during processing, ripening, and storage of traditional Greek Graviera cheese in accordance with European Union Regulation 1441/2007 for coagulase-positive staphylococci in thermized milk cheeses. Lactococcus lactis subsp. cremoris M104, a wild, novel nisin A-producing (NisA+) strain, also was evaluated as an antistaphylococcal adjunct. A three-strain cocktail of enterotoxigenic (Ent+) S. aureus increased by approximately 2 log CFU/ml when co-inoculated (at approximately 3 log CFU/ml) in thermized Graviera cheese milk (TGCM; 63°C for 30 s) with commercial starter culture (CSC) and/or strain M104 at approximately 6 log CFU/ml and then incubated at 37°C for 3 h. However, after 6 h at 37°C, significant retarding effects on S. aureus growth were noted in the order TGCM + M104 > TGCM + CSC = TGCM + CSC + M104 > TGCM. Additional incubation of TGCM cultures at 18°C for 66 h resulted in a 1.2-log reduction (P < 0.05) of S. aureus populations in TGCM + M104. The Ent + S. aureus cocktail did not grow but survived during ripening and storage when inoculated (at approximately 3 log CFU/g) postcooking into Graviera mini cheeses prepared from TGCM + CSC or TGCM + CSC + M104, ripened at 18°C and 90% relative humidity for 20 days, and stored at 4°C in vacuum packages for 2 months. A rapid 10-fold decrease (P < 0.05) in S. aureus populations occurred within the first 24 h of cheese fermentation. Reductions of S. aureus were greater by approximately 0.4 log CFU/g in CSC + M104 than in CSC only cheeses, concomitantly with the presence of NisA + M104 colonies and nisin-encoding genes in the CSC plus M104 cheeses and their corresponding microbial consortia only. A high level of selective survival of a naturally nisin-resistant EntC z S. aureus strain from the cocktail was noted in CSC + M104 cheeses and in coculture with the NisA + M104 strain in M-17 broth. In conclusion, although S. aureus growth inhibition is assured during Graviera cheese ripening, early growth of the pathogen during milk curdling and curd cooking operations may occur. Nisin-resistant S. aureus strains that may contaminate Graviera cheese milks postthermally may be difficult to control even by the application of the NisA + L. lactis subsp. cremoris strain M104 as a bioprotective adjunct culture.

The effect of household processing on the decline pattern of dimethomorph in pepper fruits and leaves

Abstract The effects of various household processes, including washing, boiling, frying, parboiling, and drying under different conditions (water amount, boiling times, and temperatures) on the residual levels of dimethomorph were evaluated in pepper fruits and leaves grown under plastic greenhouse conditions. The original quick, easy, cheap, effective, rugged, safe (QuEChERS) method (after modification) and liquid chromatography–tandem mass spectrometry (LC/MS/MS) were used for extraction and analysis to determine the sample residues. The results of recovery tests in processed and unprocessed pepper fruits and leaves ranged from 73.6 to 106.2% with relative standard deviations of 1.62–12.4%. Among various processes, washing and parboiling (78.4–85.8% at single and 75.7–89.9% at double dose) and drying after washing and parboiling (95.3–97.3% at single dose) were the most effective household methods to attenuate the analyte residues in pepper fruits and leaves, respectively. We conclude that processing leads to extensive reduction of pesticide residue levels in pepper fruits and leaves, particularly following washing and cooking operations.

Notice on a methodology for characterizing emissions of ultrafine particles/nanoparticles in microenvironments

Notice on a methodology for characterizing emissions of ultrafine particles/nanoparticles in microenvironments Jo&atilde;o Fernando Pereira Gomes,1,2 Paula Cristina Silva Albuquerque,3 Helder Manuel Dias Salva&ccedil;&atilde;o Esteves,4 Patr&iacute;cia Almeida Carvalho5 1Chemical Engineering Department, ISEL, Lisbon Polytechnic, R. Conselheiro Emidio Navarro, Lisbon; 2IBB &ndash; Institute of Biotechnoloy and Bioengineering, IST, Technical University of Lisbon, Lisbon; 3ESTESL &ndash; School of Health Tecnologies, Lisbon Polytechnic, Lisbon; 4Bioengineering Department, IST, Technical University of Lisbon, Lisbon; 5InAir, Lda., Moita, Portugal Abstract: Bearing in mind the potential adverse health effects of ultrafine particles, it is of paramount importance to perform effective monitoring of nanosized particles in several microenvironments, which may include ambient air, indoor air, and also occupational environments. In fact, effective and accurate monitoring is the first step to obtaining a set of data that could be used further on to perform subsequent evaluations such as risk assessment and epidemiologic studies, thus proposing good working practices such as containment measures in order to reduce occupational exposure. This paper presents a useful methodology for monitoring ultrafine particles/nanoparticles in several microenvironments, using online analyzers and also sampling systems that allow further characterization on collected nanoparticles. This methodology was validated in three case studies presented in the paper, which assess monitoring of nanosized particles in the outdoor atmosphere, during cooking operations, and in a welding workshop. Keywords: ultrafine particles, exposure assessment, monitoring methodology

Resolving the interactions between population density and air pollution emissions controls in the San Joaquin Valley, USA

The effectiveness of emissions control programs designed to reduce concentrations of airborne particulate matter with an aerodynamic diameter <2.5 μm (PM2.5) in California's San Joaquin Valley was studied in the year 2030 under three growth scenarios: low, medium, and high population density. Base-case inventories for each choice of population density were created using a coupled emissions modeling system that simultaneously considered interactions between land use and transportation, area source, and point source emissions. The ambient PM2.5 response to each combination of population density and emissions control was evaluated using a regional chemical transport model over a 3-week winter stagnation episode. Comparisons between scenarios were based on regional average and population-weighted PM2.5 concentrations. In the absence of any emissions control program, population-weighted concentrations of PM2.5 in the future San Joaquin Valley are lowest under growth scenarios that emphasize low population density. A complete ban on wood burning and a 90% reduction in emissions from food cooking operations and diesel engines must occur before medium- to high-density growth scenarios result in lower population-weighted concentrations of PM2.5. These trends partly reflect the fact that existing downtown urban cores that naturally act as anchor points for new high-density growth in the San Joaquin Valley are located close to major transportation corridors for goods movement. Adding growth buffers around transportation corridors had little impact in the current analysis, since the 8-km resolution of the chemical transport model already provided an artificial buffer around major emissions sources. Assuming that future emissions controls will greatly reduce or eliminate emissions from residential wood burning, food cooking, and diesel engines, the 2030 growth scenario using “as-planned” (medium) population density achieves the lowest population-weighted average PM2.5 concentration in the future San Joaquin Valley during a severe winter stagnation event. Implications: The San Joaquin Valley is one of the most heavily polluted air basins in the United States that are projected to experience strong population growth in the coming decades. The best plan to improve air quality in the region combines medium- or high-density population growth with rigorous emissions controls. In the absences of controls, high-density growth leads to increased population exposure to PM2.5 compared with low-density growth scenarios (urban sprawl).