Fuzzy clustering and distributed model for streamflow estimation in ungauged watersheds.

This paper proposes a regionalization method for streamflow prediction in ungauged watersheds in the 7461 km2 area above the Gharehsoo Hydrometry Station in the Ardabil Province, in the north of Iran. First, the Fuzzy c-means clustering method (FCM) was used to divide 46 gauged (19) and ungauged (27) watersheds into homogenous groups based on a variety of topographical and climatic factors. After identifying the homogenous watersheds, the Soil and Water Assessment Tool (SWAT) was calibrated and validated using data from the gauged watersheds in each group. The calibrated parameters were then tested in another gauged watershed that we considered as a pseudo ungauged watershed in each group. Values of R-Squared and Nash-Sutcliffe efficiency (NSE) were both ≥ 0.70 during the calibration and validation phases; and ≥ 0.80 and ≥ 0.74, respectively, during the testing in the pseudo ungauged watersheds. Based on these metrics, the validated regional models demonstrated a satisfactory result for predicting streamflow in the ungauged watersheds within each group. These models are important for managing stream quantity and quality in the intensive agriculture study area.

Graphene Decorated with Silver Nanoparticles as a Low-Temperature Methane Gas Sensor.

This paper is devoted to an investigation on the methane sensing properties of graphene (G), decorated with silver nanoparticles (AgNPs), under ambient conditions. To do so, we first present an effective modification in the standard manner of decorating graphene by AgNPs. From structural analysis of the product (AgNPs/G), it is concluded that graphene is indeed decorated by AgNPs of a mean size 29.3 nm, free of aggregation, with a uniform distribution. The so-produced material is then used, as a resistivity-based sensor, to examine its response to the presence of methane gas. Our measurements are performed at relatively low temperatures, for various silver-to-graphene mass ratios (SGMRs) and methane concentrations. To account for the effects of humidity, we have made the measurements, at room temperature, for different levels of humidity. Our results demonstrate that an increase in the SGMR enhances the response of AgNPs/G to methane with an optimum value of SGMR ≅ 12%. It is also illustrated that for methane concentrations less than 2000 ppm, the maximal response increases linearly and rapidly, even at room temperature. Moreover, we demonstrate that AgNPs/G is of low limit of detection, highly stable, selective, reversible, repeatable, and sensor-to-sensor reproducible, for methane sensing. The results thus promise a low-cost and simple-to-fabricate methane sensing device.

An ensemble prediction of flood susceptibility using multivariate discriminant analysis, classification and regression trees, and support vector machines.

Floods, as a catastrophic phenomenon, have a profound impact on ecosystems and human life. Modeling flood susceptibility in watersheds and reducing the damages caused by flooding is an important component of environmental and water management. The current study employs two new algorithms for the first time in flood susceptibility analysis, namely multivariate discriminant analysis (MDA), and classification and regression trees (CART), incorporated with a widely used algorithm, the support vector machine (SVM), to create a flood susceptibility map using an ensemble modeling approach. A flood susceptibility map was developed using these models along with a flood inventory map and flood conditioning factors (including altitude, slope, aspect, curvature, distance from river, topographic wetness index, drainage density, soil depth, soil hydrological groups, land use, and lithology). The case study area was the Khiyav-Chai watershed in Iran. To ensure a more accurate ensemble model, this study proposed a framework for flood susceptibility assessment where only those models with an accuracy of >80% were permissible for use in ensemble modeling. The relative importance of factors was determined using the Jackknife test. Results indicated that the MDA model had the highest predictive accuracy (89%), followed by the SVM (88%) and CART (0.83%) models. Sensitivity analysis showed that slope percent, drainage density, and distance from river were the most important factors in flood susceptibility mapping. The ensemble modeling approach indicated that residential areas at the outlet of the watershed were very susceptible to flooding, and that these areas should, therefore, be prioritized for the prevention and remediation of floods.

The Clinical Course of Patients With Atrial Septal Defects.

BACKGROUND: Atrial septal defect (ASD) is a common congenital heart disease. OBJECTIVES: The aim of this study was to assess the clinical course of ASD, as well as its frequency of spontaneous closure and regression of diameter. METHODS: In a study conducted from 2000 to 2011, 192 consecutive patients with an isolated ASD were followed up regularly with periodic echocardiographic evaluations according to a standardized protocol. The study was conducted in two series of patients: infants and children and adults. Infants were classified into three groups based on ASD diameter: small (≤ 5 mm), medium (6 - 9 mm), and large (> 9 mm). In the same manner, the ASD size in children and adults was categorized into three groups: small (≤ 10), medium (10 - 20 mm), and large (> 20 mm). RESULTS: The patients consisted of 76 (39.6%) males and 116 (60.4%) females. The mean age of patients at diagnosis was 16.12 ± 15.66 years (range 1 week - 75 years). The mean follow-up duration was 70 ± 9 months (range: 25 - 119 months). The most prevalent age group was adult patients (> 20 years), and most ASDs were of medium size (1 - 2 cm). The most common complication was mild pulmonary hypertension (31 cases, 16.2%), and Eisenmenger phenomenon was the rarest complication (2 cases, 1%). Overall spontaneous closure of ASD occurred in 42 (21.9%) cases. Spontaneous closure in cases with small defects occurred in 18 of 22 (81%) infants and 24 of 81 children > 1 years of age. Regression of ASD size occurred in 2 (9.5%) infants and 3 (3.7%) children. No spontaneous closure was observed in cases with a defect size > 10 mm, and no spontaneous occlusion was detected in adolescents or adults. Seventy-two percent (n = 139) of patients needed surgical repair or transcatheter closure of the ASD. CONCLUSIONS: It is concluded that atrial septal defects < 6 mm typically close spontaneously, and ASDs measuring 6 - 9 mm may regress in infants and children. An ASD > 1 cm has little chance of spontaneous closure and may need surgical or device closure. ASD diameter and age at diagnosis are the most important predictors of spontaneous closure and the need for possible surgical or device closure.

Pulmonary function tests and impulse oscillometry in severe chronic obstructive pulmonary disease patients' offspring.

BACKGROUND: Several studies have showed an increased prevalence of airflow obstruction in first degree relatives of individuals with chronic obstructive pulmonary disease (COPD). Considering no specific research had evaluated airway resistance in offspring of patients with severe COPD, we utilized a spirometry and a impulse oscillometry (IO) to evaluate this population. MATERIALS AND METHODS: In this case control study, from November 2011 to July 2012, we consecutively evaluated 54 offsprings of severe COPD patients (case group) admitted in the pulmonary ward, affiliated to the Isfahan University of Medical Sciences and control group. Pulmonary function tests and the IO were obtained for both groups. Student's t-test was used for inter-group comparisons, and P values below 0.05 were taken as significant. RESULTS: Abnormal increased airway resistance was seen in cases in comparison with controls (R5 Hz [46.29%, P = 0.01], R25 Hz [42.59%, P < 0.001]). Also, considering the spirometry, case group had pulmonary function parameters less than control group (forced vital capacity [FVC]; P = 0.02, forced expiratory volume in 1(st) s; P < 0.001, forced expiratory flow (FEF) 25-75; P < 0.001, FEF 25-75/FVC; P < 0.001) but they were in normal range. CONCLUSION: This study demonstrated increased airway resistance among the severe COPD offsprings. The IO may be a sensitive tool for detection of high risk subjects in families with COPD.

Relationship between craniofacial photographic analysis and severity of obstructive sleep apnea/hypopnea syndrome in Iranian patients.

BACKGROUND: Considering the effectiveness of craniofacial photographic analysis for diagnosis and management of obstructive sleep apnea-hypopnea syndrome (OSAHS) as well as ethnic differences in indexes measured by this method, this study designed to compare the surface facial dimensions, including nose width, intercanthal width and mandibular width of Iranian patients with mild, moderate and severe OSAHS. MATERIALS AND METHODS: In this cross sectional study subjects with mild, moderate and severe OSAHS based on apnea-hypopnea index, were studied. To determine cephalometric measurements, face and neck digital photographs were taken from participants following a standardized procedure. Cephalometric measurements including face, intercanthal and mandibular widths were compared between studied groups. RESULTS: In this study, 100 participants enrolled. From which 20 (20.8%), 35 (36.45%) and 41 (42.7%) of them had mild, moderate and severe OSAHS, respectively. Mean of nose, intercanthal and mandibular width were significantly higher in patients with severe OSAHS than those with mild or moderate OSAHS (P < 0.05). In both genders, mandibular width were higher in severe forms of OSAHS. Disease severity was significantly associated with increased age and mandibular width (P < 0.05). CONCLUSION: Mandibular width was the most important index, which had a significant association with the disease severity. It seems that our results could be used both for diagnosis and follow-up of OSAHS management. They could be used as baseline information as well as a clinical and research tool in the field of OSAHS.

Pulmonary function tests in ulcerative colitis.

BACKGROUND: Pulmonary impairment in patients suffering ulcerative colitis (UC) has been suggested by several investigators using standard pulmonary function tests (PFTs). This changes in pulmonary function associated with minimal respiratory symptoms have been documented, especially in patients with active disease. The aim of this prospective study was to determine airway resistance and lung volumes in patients with UC who have no respiratory symptoms in comparisons to a healthy control group. MATERIALS AND METHODS: We evaluated a total of 30 patients with UC by means of spirometry, body plethysmography, and impulse oscillometry. The patients were not complaining of any pulmonary symptoms and did not present any history of previous respiratory diseases. As controls we examined 30 healthy subjects matched for gender, age, and smoking status. The relationship between PFT, lung volume, and airway resistance; and the activity, localization, and duration of the UC disease were analyzed. RESULTS: There was a significant difference between airway resistances (kPa/L/s) measured by body plethysmography in patients with UC and those of the controls (R5hz; 0.60 ± 0.44 vs. 0.39 ± 0.13; P < 0.001) and R20hz (0.37 ± 0.19 vs. 0.29 ± 0.1, P = 0.02). There were no correlation between PFT, airway resistance and site and scoring activity (P > 0.05). CONCLUSION: Despite the lack of pulmonary symptoms, increased airway resistance was found in UC patients. We also have not found correlation between PFT, lung volume and airway resistance values and scoring of UC activity.

All-age relationship between arm span and height in different ethnic groups.

The objective of the present study was to establish multiethnic, all-age prediction equations for estimating stature from arm span in males and females. The arm span/height ratio (ASHR) from 13 947 subjects (40.9% females), aged 5-99 years, from nine centres (in China, Europe, Ghana, India and Iran) was used to predict ASHR as a function of age using the lambda, mu and sigma method. Z-scores for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC in 1503 patients were calculated using measured height and height calculated from arm span and age. ASHR varied nonlinearly with age, was higher in males than in females and differed significantly between the nine sites. The data clustered into four groups: Asia, Europe, Ghana and Iran. Average predicted FEV1, FVC and FEV1/FVC using measured or predicted height did not differ, with standard deviations of 4.6% for FEV1, 5.0% for FVC and 0.3% for FEV1/FVC. The percentages of disparate findings for a low FEV1, FVC and FEV1/FVC in patients, calculated using measured or predicted height, were 4.2%, 3.2% and 0.4%, respectively; for a restrictive pattern, there were 1.0% disparate findings. Group- and sex-specific equations for estimating height from arm span and age to derive predicted values for spirometry are clinically useful.

Validation of the persian version of berlin sleep questionnaire for diagnosing obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is a common but usually under-diagnosed sleep disorder. Objective diagnosis is based on polysomnography, which is an expensive test. We assessed the reliability and diagnostic accuracy of the Berlin questionnaire (BQ) in diagnosis of OSA in Iranian sleep clinic patients. METHODS: A cross-sectional linguistic validation study was conducted on consecutive Iranian patients with Persian language attending one sleep clinic in Isfahan (Iran) were studied. Patients completed the Persian BQ (contains 10 questions in 3 categories), developed by forward-backward translation method. The patients underwent an overnight polysomnographic study at the clinic. Apneas/hypopnea index of >5/Hour was considered for diagnosis of OSA. RESULTS: One hundred and fifty seven patients (55.4% male, mean age = 52.3 ± 13.6 years) were evaluated. Sleep study confirmed OSA diagnosis in 91.7% of the studied patients. The reliability analysis of the BQ categories showed alpha Cronbach's as 0.70 and 0.50 for category 1 and category 2, respectively. BQ categories 1-3 were positive respectively in 88.5%, 67.5%, and 66.9% of the patients. The BQ and sleep study were in agreement for 82.1% of the cases. The sensitivity, specificity, positive and negative predictive values, and positive, and negative likelihood ratio of the BQ were calculated as 84.0%, 61.5%, 96.0%, 25.8%, 2.18%, and 0.26% respectively. CONCLUSIONS: BQ is useful as a screening test for diagnosing OSA in Iranian patients with sleep complaints; however, the test cannot be used for rolling out the OSA. Further studies on editing, modifying, and applying the BQ in a larger sample of patients are warranted in our society.

Impact of ethanol, dry care and human milk on the time for umbilical cord separation.

OBJECTIVE: To compare the extraction time and infection rate of umbilical cord by applying ethanol, humanmilk or dry care. METHOD: The parallel single-blinded randomised clinical trial was performed on 300 neonates at Shahid Sadougi University of Medical Sciences and Health Service, Yazd, Iran, between March and September 2010. The neonates were divided into three random but numerically equal groups. Each group was assigned the application of ethanol or mother's milk or to keep the stump dry. The neonates were visited on the 3rd and the 7th day after birth and follow-up was maintained telephonically until umbilical separation. Umbilical separation time and umbilical local infection frequency were considered as the study outcome, which was compared among the three groups according to age, gender and delivery type of the neonates. RESULTS: Umbilical separation time in neonates of the human milk group had significant difference with the ethanol group (p=0.0001) and drying groups (p = 0.003). Frequency of omphalitis had no significant difference among the three groups. CONCLUSION: Topical usage of human milk on umbilical cord stamp decreased separation time and incidence rate of omphalitis.

Effect of body massage on increase of low birth weight neonates growth parameters: A randomized clinical trial.

BACKGROUND: Admission of low birth-weight (LBW) neonates in neonatal intensive care unit (NICU) causes their deprivation of tactile and sensory stimulation. OBJECTIVE: The purpose of this study was to evaluate efficacy of body massage on growth parameters (weight, height and head circumference) gain velocity of LBW in Yazd, Iran. MATERIALS AND METHODS: A randomized clinical trial study was conducted on LBW neonates whom were admitted to NICU of Shahid Sadoughi Hospital, Yazd, Iran from March to December 2011. Neonates were randomly assigned to two groups. In group one, 20 neonates were received massage three times in a day for consecutive 14 days by their mothers. In group two, intervention consisted of standard and routine care as control group. The primary endpoints were efficacy in increase of mean of weight, height and head circumference that were evaluated 14 days after intervention, at ages one and two months. Secondary outcome was clinical side effects. RESULTS: 17 girls and 23 boys with mean gestational age of 34.4±1.22 weeks were evaluated. In the body massage group, only weight at the age of two months was significantly higher than the control group (mean±SD: 3250±305 vs. 2948±121 gr, p=0.005). No adverse events were seen in the two groups. CONCLUSION: Body massage might be used as an effective and safe non-medical intervention for increasing of weight gain velocity in LBW preterm neonates.

Sleep Apnea Symptoms in Diabetics and their First Degree Relatives.

BACKGROUND: Sleep apnea is associated with increased risk of diabetes mellitus. However, no studies have compared sleep apnea symptoms in diabetic patients and their first degree relatives. The purpose of our study was to investigate high risk for sleep apnea syndrome, in diabetics and their first degree relatives for prevention of diabetes in family. METHODS: As a part of a cohort study, all of diabetic and their first degree relatives who came for glucose control in diabetes clinic were invited to take part in the survey. Two thousand, four hundred and sixty-two individuals (82% of invited) agreed to fill out the Berlin and Epworth sleep questionnaire. Participants consisted of 2462 subjects of 15-70 years of age, both males and females with diabetes and family history of type 2 diabetes mellitus. A total of 1234 participants had diabetes and 11,231 were relatives of diabetic patients. High risk for sleep apnea regarding Berlin questionnaire and Epworth sleepiness scale, diabetic and relative were analyzed. RESULTS: Prevalences of high risk for sleep apnea were higher among diabetics than relatives (P-value<0.001). In a multiple regression analysis, "age, body mass index, education, high blood pressure" were risk factor for sleep apnea symptoms while isolated blood glucose level was not by Berlin questionnaire. By Epworth sleep scale only education level was a risk factor for sleep apnea symptoms while isolated blood glucose level was not risk factor. CONCLUSIONS: Sleep apnea symptoms may not have significant difference between diabetics and their relatives. We need more study on sleep apnea in the family of diabetic patients. We hope that more studies on mentioned field may help prevention of diabetes in their family.

Sleep apnea symptoms and accident risk factors in Persian commercial vehicle drivers.

BACKGROUND: Motor vehicle accidents are the second highest cause of mortality in Iran. Sleep apnea symptoms have been associated with increased risk of motor vehicle accidents in other countries. However, we have limited data in Iran. We conducted a study to evaluate sleep apnea symptoms and sleepiness in professional drivers and to assess the predictors of motor vehicle accidents in Iran. METHODS: A questionnaire-based cross-sectional study of drivers was done in Shahrekord, Iran. This study used a self-administered questionnaire that included personal information, the Epworth sleepiness scale (ESS), the Berlin questionnaire, and history of previous automobile accidents. Nine hundred thirty-one male drivers (62% of invited drivers), aged 40.2 ± 10.1 years (mean±SD), were included in the study. The mean number of hours spent driving was 48.9 h/week. The median distance covered weekly was 2,905 km/week. Statistical analysis included logistic models with covariate-adjusted P values of <0.01 s (odds ratios and 95% confidence intervals or limits). Independent accident predictors were sought. RESULT: The professional drivers with car accidents had a higher risk in Berlin questionnaire (P < 0.02), a larger mean neck circumference (P < 0.04), and more witnessed apneas (P < 0.04). There was no significant association between in drivers with car accident and ESS above 10. CONCLUSIONS: In Persian professional drivers, high-risk Berlin questionnaire, larger neck circumference, and a history of witnessed apneas were the most important predictors of motor vehicle accident.

Prevalence of sleep apnea-related symptoms in a Persian population.

PURPOSE: There are no published data regarding the prevalence of obstructive sleep apnea (OSA) in Iran. The purpose of this cross-sectional study was to identify individuals with a high likelihood to suffer from obstructive sleep apnea in the Persian population. This was compared to similar studies in other countries. MATERIALS AND METHODS: As a part of a population-based cross-sectional study, 3,600 randomly selected individuals aged 18 years or more, were invited to take part in the survey, 3,529 individuals (98%) agreed to fill out the Berlin sleep questionnaire. RESULTS: Based on the Berlin Criteria, 176 subjects (4.98%) were identified as suspicious for OSA. This group consisted of 74 (42%) males and 102 (58%) females. The prevalence of high-risk Berlin in men and women were not significantly different with chi-square test (p > 0.2). But high-risk Berlin subjects also were increasing with age (p < 0.001) and increasing with obesity (p < 0.001) and decreasing with higher education (p < 0.001) with chi-square test. Predictors of high risk for OSA-related symptoms were female sex, age more than 50 years, and body mass index. CONCLUSIONS: We identified persons with a high risk for OSA among a representative Iranian sample. It is concluded that the prevalence of sleep apnea syndrome symptoms is lower in our population as compared with western countries which can be attributed to the excessively young Iranian population.

Comparison of impulse osillometry system and spirometry for diagnosis of obstructive lung disorders.

BACKGROUND: Obstructive lung disease is a growing health problem, especially in developed countries. This study aimed to compare Impulse Osillometry System (IOS) and Spirometry for evaluation of Chronic Obstructive Pulmonary Disease and asthma. MATERIALS AND METHODS: The study groups contained 87 healthy people, 87 asthmatic patients and 56 COPD patients. Spirometry (FVC, FEV1, FEV1/FVC) and IOS (R5, R20, X5) measurements were performed for all the healthy subjects and patients. The results of IOS were compared with spirometric results. RESULTS: Significant differences were detected among the 3 groups (control, COPD and asthma) in terms of all the spirometric parameters (FVC, FEV1, FEV1/FVC) and some parameters of IOS (R5,R20,X5) measurements (p<0.05). Among COPD patients, sensitivity for X5 (the best value of IOS measurements in the COPD group) was 76%. Also, in asthmatic patients, sensitivity for R20 (the best value of IOS measurements in the asthma group) was 77%. We found a correlation between R5, R20 and X5 with FEV1 in asthmatic patients, but only R5 had this correlation with FEV1 in COPD patients. CONCLUSION: We concluded that IOS can be an alternative for spirometry in the diagnosis of obstructive lung disease in patients with minimal cooperation. R5 can represent COPD severity.

Sample survey of chronic obstructive pulmonary disease and associated risk factors in isfahan, iran.

BACKGROUND: The purpose of this cross-sectional study was to estimate the number of individuals with chronic bronchitis and/or chronic obstructive pulmonary disease in Isfahan. Our study results were compared with those of previous studies in Iran and similar studies in other countries. MATERIALS AND METHODS: As a part of a population-based, cross-sectional study, 2,200 randomly selected individuals aged 40 years or older were asked to take part in the survey; among whom, 1308 individuals (59.45%) agreed to fill out the respiratory questionnaire. This group consisted of 636 (48.6%) males and 672 (51.4%) females. Spirometric measurements were performed in 279 cases. COPD was defined by the "Global Initiative for Obstructive Lung Disease" criteria. RESULTS: One hundred-seven individuals (8.1%) fulfilled the clinical criteria for chronic bronchitis as the main sign of COPD. Multivariate analysis revealed that age and smoking were independent predictors for chronic obstructive pulmonary disease. CONCLUSION: It is concluded that the prevalence of chronic bronchitis symptoms is approximately the same in our population as compared with western countries. The frequency of clinical chronic bronchitis has risen in comparison to a previous study in Isfahan.

Correlation between chronic obstructive pulmonary disease and obstructive sleep apnea syndrome in a general population in Iran.

BACKGROUND: The aim of this study was to evaluate epidemiological relationship between chronic obstructive pulmonary disease and sleep apnea syndrome in a sample of Persian population. METHODS: As a part of a population-based cross-sectional study, 3900 randomly selected individuals aged 15 years or older were invited to take part in the survey; 3770 individuals (96.6%) agreed to fill out the respiratory and sleep questionnaire. Those subjects suspected to have either chronic obstructive pulmonary disease and/or obstructive sleep apnea underwent spirometry and polysomnography test if indicated. Spirometric measurements were performed on 420 invited responders. Polysomnography measurements were performed on 25 of the responders. RESULTS: Prevalence rates for sleep apnea, chronic obstructive pulmonary disease and current asthma were 4.98%, 5.7% and 3.1%, respectively. Logistic regression showed independent associations between sleep apnea and chronic obstructive pulmonary disease. There was no significant independent association between sleep apnea symptoms and current asthma and wheeze ever. CONCLUSIONS: These observations indicated relationship between chronic obstructive pulmonary disease and obstructive sleep apnea. These observations indicated the necessity of further studies to explain the possible common pathogenic mechanisms involved in two disease entities.

Endothelial dysfunction in patients with obstructive sleep apnoea independent of metabolic syndrome.

INTRODUCTION: Obstructive sleep apnoea syndrome (OSAS), characterised by intermittent hypoxia/re-oxygenation, has been identified as an independent risk factor for cardiovascular diseases and endothelial dysfunction. Our aim was to investigate flow-mediated dilatation (FMD) in patients with obstructive sleep apnoea with and without metabolic syndrome. MATERIALS AND METHODS: Fifty-two subjects with OSAS diagnosed by polysomnography were classified into 2 groups according to the presence and absence of the metabolic syndrome and also according to the severity: mild to moderate OSAS group and severe OSAS group. Endothelial function of the brachial artery was evaluated by using high-resolution vascular ultrasound. Endothelial-dependent dilatation (EDD) was assessed by establishing reactive hyperaemia and endothelial-independent dilatation (EID) was determined by using sublingual isosorbide dinitrate. Spearman correlation and regression analysis were performed. RESULTS: EDD was not significantly different in patients with OSAS and metabolic syndrome as compared with OSAS without metabolic syndrome (4.62 +/- 0.69 versus 4.49 +/- 0.93, P >0.05). CONCLUSIONS: Endothelial dysfunction in OSA may be independent of metabolic syndrome.

Reference values for lung volumes in an Iranian population: introducing a new equation model.

BACKGROUND: Measurement of lung volumes, especially residual volume and total lung capacity are essential for assessment of restrictive lung disorders. Information regarding normative prediction values for lung volumes as measured by body plethysmography is scarce, and plethysmographic parameters are believed to be poorly reproducible. In this study, we report a comprehensive set of predictive equations for static lung volumes from a general population sample of urban Iranians as measured by body plethysmography. METHODS: Standardized measurements were carried out on 1487 healthy nonsmoking volunteers (845 men and 642 women), aged six to 85 years, living in Isfahan, Iran. Nonlinear multiple regression analysis was used to calculate prediction equations based on subjects' ages and heights for the subdivisions of lung volumes [total lung capacity, functional residual capacity, residual volume, and residual volume/total lung capacity (%)], separately for the two genders. The derived equations were used to calculate prediction values for the subjects. The two sets of predicted and measured values were compared by paired sample t-test. RESULTS: Prediction equations based on a new nonlinear model, (alpha(1) x age + alpha(2) x age(n) + beta x height + c) which best fitted our data are presented. The measured and predicted values closely resemble and there is no significant difference between the two sets. Since increments in total lung capacity, functional residual capacity, and residual volume disclose air trapping within the lungs, their upper limits of normal are as important as the lower limits. So, we have presented both for the equations. CONCLUSION: Despite the usual beliefs we found rather reproducible prediction equations with high coefficient of determination (r2) and low standard error of estimate (SEE) in Iranian population.