Wet Blue Leather Research Articles

Optimizing extraction of collagen from hazardous leather shaving dusts by crude protease enzyme: Chrome recovery and reuse for leather rechroming

This study explores an eco-friendly method to achieve 99.98 % dechroming (reducing Cr from 7700 to 4.71 ppm) of Chrome-tanned leather shaving dust (CSD), through enzymatic hydrolysis using crude protease. The enzyme exhibited strong activity (>40 U mL−1) across a temperature range of 50 °C to 65 °C and a pH range of 5 to 11. The pH of the mixture containing CSD, water, MgO, and enzyme was maintained at 8.9 during hydrolysis. The temperature, hydrolysis time, and enzyme concentration were optimized using response surface methodology (RSM). Under optimal conditions of 17.57 % enzyme concentration, 62.01 °C, and a hydrolysis time of 7 h, the predicted collagen yield was 31.66 %. Laboratory experiments conducted with these predicted parameters resulted in a collagen recovery of 30.9 %, achieving an accuracy of 97.6 % compared to the predictions. In contrast, hydrolysis with MgO alone achieved only 87.01 % dechroming with about 2 % collagen yield, highlighting the enzyme's superior effectiveness. The enzymatic cleavage of peptide bonds in the leather matrix enhanced collagen solubilization. Characterization techniques, including FT-IR, NMR, XRD, DSC, and TGA, confirmed successful extraction and purity, with the collagen being rich in glycine and proline. Cytotoxicity results demonstrated its non-toxic nature, indicating potential applications in biomedical fields, tissue engineering, food, pharmaceuticals, and cosmetics. The recovered chromium sulfate was reused for rechroming goat wet blue leather, with chrome content in crust leather treated with recovered basic chromium sulfate (rBCS) and fresh basic chromium sulfate (BCS) being 3.23 % and 3.35 %, respectively, both meeting industry standards for goat crust leather. SynopsisAn eco-friendly method for dechroming chrome-tanned leather shaving dust (CSD) and extracting collagen was established. The process achieved 99.98 % dechroming and 30.9 % collagen yield using crude protease enzyme. Characterization confirmed the collagen's purity, and recovered chromium sulfate was reused for rechroming goat leather, meeting industry standards.

Integrated circular economic approach of solid waste management and resource recovery: Poultry feather-based keratin extraction and its application in leather processing

The tanning industry faces considerable environmental challenges due to effluent load and hazardous chemical generation during processes like tanning and retanning. Therefore, this research work addresses these issues focusing on the pilot scale extraction and application of poultry feather-based keratin hydrolysate (KH) in leather manufacturing. Through pilot-scale experiments, optimal parameters for NaOH concentration, reaction temperature, and time were used to extract KH effectively. The study explored KH's potential application in chrome tanning and retanning stages as a chrome exhaust aid and keratin filler, respectively. During basification, KH was introduced to enhance chromium uptake by creating additional sites through the provision of crosslinking with collagen (modifying collagen) for better interaction and formation of complex with chromium, which not only streamlined the process by reducing the need for additional chemicals but also improved the thermal stability of the resulting leather product and enhance, the quality of leather. The shrinkage temperature of experimental wet blue leather was recorded to be above 107oC compared to the control wet blue leather which start to shrink at 104oc. Similarly, the percentage chromic oxide content of the experimental wet blue leather was observed to be significantly higher (3.89±0.20%) than that of the control wet blue leather (2.59±0.15). Furthermore, KH replaced commercial protein fillers during retanning, resulting in leathers with enhanced mechanical strength and organoleptic properties. The experimental crust leather treated with keratin solution at pH (5.5) was determined to have better tensile strength (23.4 N/mm2) and tear load (38.7 N/mm) than the control leather with tensile strength and tear load of 19.4 N/mm2 and 29.1 N/mm, respectively. Analytical techniques such as FTIR and XRD confirmed the presence of essential functional groups and protein structures in the KH solution, respectively. Leathers treated with 100 % KH substitution at pH value of 5.5 exhibited superior properties, including increased mechanical strength and thermal stability. Environmental impact assessments revealed a significant reduction in total dissolved solids in the spent liquor when KH replaced conventional fillers. Overall, this research demonstrates the potential of poultry feather-based keratin as an efficient, environmentally friendly filler in leather manufacturing, offering promising results in improving product quality and reducing environmental pollution.

Chrome Uptake and Thermal Stability of Wet Blue Leather Tanned by Static and Rotating Drum

Leather tanning can be done by soaking the skin in pits or rotating in tannery drums. Technical soaking of rotate movement and static soaking affects the skin microstructure matrix. This study aims to compare the quality of wet blue leather tanned by static soaking in a vessel and rotating in a tannery drum, particularly in terms of chrome uptake and thermal stability. The penetration time in the soaking experiment varied from 8, 16, 24, 32, 40, 48, and 56 hours. Meanwhile, the control was processed in a small-scale tannery drum with two hours of penetration time. Then, each sample was subjected to basification using HCOONa and NaHCO3. The results showed that all samples increased in weight and thickness after tanning. After penetration, wet blue leather tanned in a tannery drum performed better blue-green colour evenness compared with the soaked ones. Tannery drum leather also showed better chromium uptake, shrinkage temperature, and thermal stability. When the drum rotates, the pickled pelt gets mechanical action, such as being stretched, bent, and slammed, helping the collagen fibre open and the chromium penetrates deeper and faster. This study revealed that darker wet blue leather indicates higher thermal stability and chromium uptake.

Leather shaving dust utilization in brick preparation: Solid waste management in tannery

In the tannery, after sammying and splitting, the flesh side of wet-blue leather is shaved getting a uniform thickness known as shaving. During shaving, a significant amount of chromium-containing leather shaving dust (LSD) is generated. It affects the environment and the management of chromium-containing LSD is a great challenge. In this work, LSD is used in brick production mitigating the generated solid waste in a tannery. The LSD (w/w) of 0%, 2%, 3%, 4%, 5%, 6%, and 7% are incorporated along with clay and burned at 1000 °C in the brickfield. The outcome discloses 4% LSD amended brick showed the maximum engineering and chemical properties. The optimum 4% LSD amended brick’s weight loss, shrinkage area, water absorption, compressive strength, and efflorescence properties to be 11.38%, 5.51%, 14.26%, 10.69 N/mm2, and no efflorescence, respectively. The Scanning Electron Microscope (SEM) images denote the micro-fibrous structure of the composite that played a significant role in producing lightweight brick. The NEN 7345 leaching test of the LSD-incorporated bricks indicated that leached metals were below the acceptable limit. Utilization of LSD will open an eye as an ingredient in brick production, to mitigate tannery solid waste load.

The Properties of Tannery Waste Addition as a Filler Based on Two Types of Polymer Matrices: Poly(Butylene Adipate-Co-Terephthalate) (PBAT) and Poly(Butylene Succinate) (PBS)

Wet blue leather is a waste produced by the leather industry. It is a difficult waste product to dispose of, and if not disposed of properly, it will affect the environment and cause toxicity. Therefore, recycling was considered as an alternative to waste disposal. In this study, polymer composites were prepared from two types of polymers, poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) (PBS), and wet blue leather (WBL). A twin screw extruder and injection molding were used to prepare the composites. The effect of polymer type and WBL content (5, 10, and 15 wt%) on mechanical properties, thermal properties, flammability, MFI, water absorption, and morphology was investigated. All the polymer composites showed an increase in tensile and flexural strength, Young’s modulus, and water absorption but decreased in elongation at break, impact strength, and flammability compared to neat polymers.

The Effect of Heating Time on the Thermal Stability of Chrome-Tanned Leather

Chrome tanning is an essential process to convert raw animal skin into leather, in which collagen, as the main structure of leather, is stabilized against degradation through cross-linking using chromium, consisting of two steps: penetration and basicity. However, the uptake of chrome in leather still needs to be improved. The purpose of this study was to find the best heating time in the chrome tanning process by thermal analysis. Pickled sheepskin was used as raw material for the chromium tanning process. The samples were varied into four categories: heated at the penetration stage of the tanning process (Initial Heating), heated at the basification stage of the tanning process (Final Heating), and heated both at the penetration and basification stage (Continuous Heating). In this study, the thermal stability of wet blue leather was evaluated by shrinkage temperature behavior (Ts), thermogravimetry analysis (TGA/DTG), and differential scanning calorimetry (DSC). The tanning efficiency was measured by Cr2O3 content. The results demonstrated that wet blue samples heated continuously shows better thermal characteristics. In conclusion, the results can be used for finding the best possible technique for the leather tanning process using chrome salts to gain thermal stability.

Eco-Friendly Valorization and Utilization of Plant Waste as a Source of Tannin for Leather Tanning

In the present study, bark, which is the waste part of a tree, was utilized as a source of tannin for leather tanning after its value addition. The barks of Acacia nilotica L. and Eucalyptus globulus, which are abundantly available in Pakistan, were selected in this study. Different extraction techniques including mechanical, soxhlet, reflux and ultrasonic extraction were used for the extraction of tannin from the selected barks. The medium of extraction included aqueous as well as different solvent mixtures in different ratios. The solvent mixtures used in this study were methanol-water and acetone–water. The methanol–water ratio was kept (50:50) and the acetone–water ratio was maintained at (50:50 and 70:30). In the first step, the process of extraction was optimized for solvent mixtures and extraction time by taking a fixed dose (5 g) of each bark and a fixed volume of each extracting solvent mixture (150 mL). The total phenolic contents (TPC) of the bark extracts were determined by colorimetric assay (as mg GAE/g bark), taking gallic acid as the reference standard. The tannin contents (TC) of the bark extracts were determined by using the standard hide powder method (SLC 117). It was concluded that among the different extraction techniques, and among the solvent mixtures acetone–water in ratio (70:30), ultrasonic extraction resulted in maximum extraction of tannin (196.1 and 125.2 mg/g), respectively for A. nilotica and E. globulus. FTIR analyses of the dried extracts obtained from both barks were compared with FTIR of the most commonly used commercial vegetable tanning agent in the leather industry, i.e., mimosa. Results were comparable, which confirmed the presence of condensed tannin in both barks. The extracted tannin was applied on a pickle and wet blue leather to evaluate its tanning and re-tanning capability. Mimosa, the most abundantly used vegetable tanning material in the leather industry, was applied as a reference standard on the same pickle and wet blue leather for comparison. Different physical properties, such as leather shrinkage temperature, leather softness, tensile strength, percent elongation and breaking strength, were measured to evaluate the tanning efficacy of the extracted tannins. The results showed that tannin obtained from A. nilotica showed comparable physical properties to those of mimosa. It was concluded from the results that tannin obtained from locally available bark, i.e., A. nilotica, can be utilized as a vegetable tanning agent for the leather industry.

Gelatinase Microbial Morphology from Leather Defect

Microbes attach in pickle leather, wet blue leather, and upper shoeleather have been identified to have positive profile to produce extracellular protease enzymes with pH values of acidic to basic on 15% gelatin and 2% commercial skimmed milk as substrates. Defective tanned leather was added to a microbial growth solution enriched with 2% gelatin substrate and incubated for 7 days at room temperature on an open rotary shaker at 120 rpm and then stored at room temperature while waiting for gelatinase testing. There were 5 morphological colonies of microbial gelatinase from defective tanned skin, all of which were white.

Nonionic Short Fluorocarbon Chain Surfactants for Improving Application Properties of Acrylic Resin in the Retanning of Wet-blue Leather

Acrylic resin (AR) is one of the most commonly used leather retanning agents owing to its excellent selective filling property and low cost. However, there are some defects affecting the quality of wet-blue leather in the practical application of AR, such as “excessive convergence”, “detanning”, and “fading”. Herein, the nonionic short fluorocarbon chain surfactants (F6-m) combined with AR for retanning wet-blue goat leather to further improve the application properties of AR. In a series of comparative experiments, the grain surface state and mechanical properties of leather retanned with 4 wt% AR and 2wt% F6-400 are preferred. Moreover, after dyeing, the dye adsorption rate and a* (red-greenness) value of AR/F6-400 retanned leather are higher than that of leather retanned with AR alone. The above issues reveal that F6-400 can improve application properties of AR in the retanning of wet-blue leather to a certain extent, benefiting to further upgrade the quality of leather.

Leather-like composite materials prepared from natural rubber and two leather wastes: Wet blue leather and finished leather

In this study, leather-like composites were prepared from natural rubber (NR) and two different types of leather waste, namely wet blue leather (WBL) and finished leather (FL). Compounding was carried out on an internal mixer and two-roll mill, and curing was further conducted on a compression molding machine. The effects of leather type and content from 20 to 80 parts per hundred of rubber (phr) on cure characteristics, mechanical properties (hardness and tensile properties) and thermal stability of the as-prepared composites were investigated and compared with those of the unfilled NR compound. The curing rate and crosslink density of all composites were found to be lower than those of the unfilled NR. All WBL-filled NR composites exhibited higher tensile strength than the unfilled NR, while all FL-filled NR composites had lower values. Meanwhile, the hardness and modulus at 200% strain of all composites were increased with increasing leather waste contents compared to those of the unfilled NR. The composites containing low WBL loadings (20 and 40 phr) demonstrated higher elongation at break over the unfilled NR, while the other composites exhibited lower values. Besides, the thermal stability of all NR composites was deteriorated, but still largely retained.

Bio-organic fertilizer production from industrial waste and insightful analysis on release kinetics

The present study has been designed to utilize industrial and agricultural solid waste for NPK (Nitrogen–Phosphorus–Potassium) bio-organic fertilizer production and its optimized use. The collagenic material of wet blue leather (WBL) from leather industry was used as nitrogen source, after H3PO4 acid-mediated chromium removal. Chicken meat-bone meal (CMBM) and rice husk ash (RHA) are abundantly available locally, had used as P, K, and Ca sources. The presence of N, P, K, Ca in the produced bio-organic NPK fertilizer were 10.76, 11.03, 3.41, 13.64, respectively as per mixing ratio of ingredients. In this study it was effect on the chili plant (Capsicum annuum L.) growth and revealed 1.15 and 1.03 fold higher plant growth, 1.40 and 1.18 fold higher total chlorophyll content than untreated soil (control), and chemical fertilizer. The liberation of fertilizers components from their source, transport of fertilizer components in the soil, and absorption in plant roots have been studied using mathematical models indicating the optimum fertilizer use for better productivity and to reduce loss of extra fertilizer and eutrophication. The formulation showed excellent water retention capability (3.2 L/kg), which might increase soil water availability to the plants and eventually reduce water demand and labour cost. DNA intercalation study proved there is no harm to use this fertilizer.

Development of natural fibre based flexural composite: A sustainable mimic of natural leather

A natural fibre based flexural composite has been developed by using suitable chemical formulation of natural rubber, sulphur dispersion, accelerator, activator, stabilizer, filler antioxidant etc. with needle punched ramie non-woven fabric. Developed natural fibre based flexural composite products have been examined in terms of different physical properties like absorbency, wicking, swelling, shrinkage. The performance properties i.e abrasion resistance, tensile strength, tear strength, puncture resistance, permeability, porosity and dynamic loading and recovery of the developed product has also been examined and compared with the wet blue (chrome treated) leather of goat. Absorbency time and rate of vertical wicking of the wet blue leather are almost equal as compared to the developed flexural composite whereas composite product shows 20 % higher permeability and less shrinkage as compared to the natural leather. Tensile strength of the developed product was 50 % less whereas tear strength is almost equal as compared to the natural leather, having same weight and thickness. Surface and cross-sectional morphology of the flexural composite and natural leather has also been characterized by scanning electron microscopy analysis. The thermo-gravimetry (TG), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) analysis of developed composites have also characterized. and compare with the natural leather.

Effective leather procurement strategies for leather products retail industry

Now a days lot of corporate giants and World leading brands such as TATA ,Aditya Birla Group, Reliance, Future group, Walmart, Zara etc.. has been performing well in the leather retail industries. As to promote a leather product as a retail brand or to promote the sales of an existing brand the retailer has to attract the customers through their discounts, quality, services and customer focus. Giving discounts and to reduce the product price ,it is mandatory to reduce or minimize the product costing. In leather production the leather is the essential raw material. Reducing the leather products cost, retailers have to minimize the raw /wetblue leather purchase price. But this may not happen because the supplier of raw leather / Wetblue leather is influenced by the availability of good quality leather, animal slaughtering rate and the demand for superior selection / superior grade leather. This study is attempted to know alternative leather procurement methods which is required for leather and leather products industry. The data are collected from 80 samples at TATA International Ltd -Chennai by using convenience sampling Techniques.

Determination of Cr(VI) in leather residues using graphite/paraffin composite electrodes modified with reduced graphene oxide nanosheets

In this study, we determined the Cr(VI) in samples of tanned leather residues by differential pulse voltammetry (DPV) using graphite/paraffin composite electrodes modified with reduced graphene oxide nanosheets (referred to as GPEs/nsRGO). After the modification, the composite electrodes were characterized by two electrochemical techniques (i.e., cyclic voltammetry, CV, and electrochemical impedance spectroscopy, EIS), scanning electron microscopy, and Raman spectroscopy. The electroanalytical method was applied using the GPEs/nsRGO. An analytical curve was obtained in a Clark-Lubs buffer solution (pH = 1), with a linear concentration range from 25.0 to 392.0 μmol L−1 and a limit of detection (LOD) of 1.01 μmol L−1. The GPEs/nsRGO showed good reproducibility in their manufacturing process and good response repeatability with an RSD of 4.59% over twelve measurements. These composite electrodes showed excellent selectivity, which was demonstrated by analyses in the presence of metal ions (Ca2+, Zn2+, Mg2+, Fe3+, Co2+, Na+, and Cu2+) that did not interfere in the analysis of Cr(VI). The GPEs/nsRGO were applied to the determination of Cr(VI) in real samples of wet-blue leather and leather ash using DPV. This approach was validated using the sample recovery method, where it presented values from 95.6 to 108.2%. The proposed method showed satisfactory results compared to the literature and can be considered a good alternative for the determination of Cr(VI) in aqueous samples.

Novel Ester-bonded Gemini Quaternary Ammonium Salt with Good Antimicrobial Activity and Anti-mold Performance for Wet Blue Leather

Herein, we have developed a kind of novel ester-bonded gemini quaternary ammonium salts microbicides named QAS(n+m) for leather application, in which n and m denotes the number of −CH2 between the ester groups on the spacer, and the length of alkyl chain connected to ester groups on the hydrophobic tail chain, respectively. Results indicate that the hydrophobic tail lengths and the spacer lengths in the QAS(n+m) structures affect their antimicrobial activities very differently. QAS(4+10) was used to investigate the antimicrobial mechanism, cytotoxicity, and antimold performance for wet blue leather as it exhibits the strongest antimicrobial effect. It shows QAS(4+10) is capable of inactivating microorganisms mainly by disrupting the integrity of their cell membranes. Compared to commercial leather microbicide product 2-thiocyanomethylthiobenzothiazole (TCMTB), QAS(4+10) exhibits comparable mold resistance and lower toxicity. The present work gives positive insight into the development of novel candidate microbicides for the preservation of wet blue leather.

Mitigating the Formation of Hexavalent Chromium in Leather by Using Aloe Barbadensis Miller Mixed with Carrageenan

Aloe barbadensis miller (Abm) mixed with carrageenan has been investigated as an alternative eco benign ingredient in mitigating hexavalent chromium Cr (VI) formation in thermally and photoaged wet blue and leather crust. The effect of post-tanning operations on the formation of Cr (VI) in wet blue and leather crusts due to spontaneous and accelerated ageing caused by exposure to the temperature of 80 °C and UV radiations for 132 hours is also presented. The Cr (VI) content was analysed according to ISO 17075 standard procedure of Diphenyl carbazide and UV-VIS spectrophotometer at 540 nm. The levels of Cr (VI) in retanned wet blue leather were detectably high, while for tanned, dyed and fatliquored crusts, the levels were below detection limit of 0.2247 mg/kg. After ageing, the Cr (VI) content increased to a detectable level, the highest recorded in retanned wet blue, followed by fatliquored crust and with the lowest levels recorded in dyed wet blue leather. In all the aged samples, the levels were remarkably higher than the recommended 3 mg/kg. The levels of Cr (VI) in wet blue leathers processed with Abm/carrageenan were below detection limit of 3.587 mg/kg, even after exposing the samples to accelerated ageing conditions. Abm/carrageenan completely inhibits formation of Cr (VI) in wet blue and leather crusts. Abm/carrageenan will contribute to the eco benign and sustainable production of leather under the superior chrome-tanning technology.

Lightweight network study of leather defect segmentation with Kronecker product multipath decoding.

In the leather production process, defects on the leather surface are a key factor in the quality of the finished leather. Leather defect detection is an important step in the leather production process, especially for wet blue leather. To improve the efficiency and accuracy of detection, we propose a leather segmentation network using the Kronecker product for multi-path decoding and named KMDNet. The network uses Kronecker products to construct a new semantic information extraction layer named KPCL layer. The KPCL layer is added to the decoding network to form new decoding paths, and these different decoding paths are combined that segment the defective part of the leather image. We collaborate with leather companies to collect relevant leather defect images; use Tensorflow for training, validation, and testing experiments; and compare the detection results with non-machine learning algorithms and semantic segmentation algorithms. The experimental results show that KMDNet has a 1.99% improvement in F1 score compared to UNet for leather and a nearly three times improvement in detection speed.

From waste to value-added products: Evaluation of activated carbon generated from leather waste for supercapacitor applications

Leather tanning operations create a large amount of solid and liquid waste from tanning, wherein Cr(III) compounds are used to produce wet blue leather. In this study, activated carbon (AC) generated from leather waste (LW) was evaluated for supercapacitor (SC) applications. AC was produced through carbonization at a temperature range of 700°C–900 °C, followed by chemical activation. The morphological characteristics of the AC samples revealed a certain degree of porosity and a maximum surface area of 381 m2 g−1. X-ray diffraction and EDX examination showed the existence of graphitic planes in the LW-derived AC. Raman, FT-IR, and XPS confirmed the defect nature and surface functional groups of the AC samples. A three-electrode approach was employed to assess the electrochemical characteristics of the AC samples. The supreme capacitance of a sample (LW700) at 1 A/g was 550 F g−1 (237 C g−1) in a 6 M KOH electrolyte. All the electrochemical results (CV, GCD, and Nyquist curves) demonstrated that the LW carbon possessed a high specific capacitance and electrochemical cycle constancy, and hence is appropriate for SC fabrication. These desirable capacitive performances enable solid leather waste-derived carbons as a source of new materials for low-cost energy storage supercapacitors. This work put forwards a new concept of ‘waste to value-added products’ that can be a helping hand for leather industries and its solid waste management disposal problems.

Improvement of hydrothermal stability and chrome uptake of leather: Amino-terminated hyper-branched polymer as high exhausted tanning auxiliary

Carboxyl-terminated hyper-branched polyester is extensively used as high exhaustion chrome tanning auxiliary owing to its strong coordination ability with trivalent chrome. Owing to lower electronegativity of N than O, the coordination ability with trivalent chrome for hyper-branched polyamide is stronger than polyester. Herein, in this paper, an amino-terminated hyper-branched polyamide (HBPN) is synthesized and used as high exhaustion chrome in tanning of pickling pigskin (HBPN–Cr). The effects of utilization of HBPN in denaturation temperature, shrinkage temperature, chrome uptake, and microstructure structure of wet-blue leather are studied. Moreover, the anti-oxidation stability of wet-blue leather is preliminary studied by heat treatment. The results show that incorporation of 1% HBPN in pickling process can significantly improve chrome uptake to 83.32%. The hydrothermal stability of wet-blue leather is improved due to the formation of higher crosslinking degree of collagen fibers. In addition, for the wet-blue leather without unsaturated fatliquoring agent, through heat treatment, hexavalent chrome does not appear after 24 ​h heat treatment. On the contrary, the chrome complex changes from hydroxyl copolymerization to more stable oxygen copolymerization or chrome oxide for C–Cr and HBPN-Cr tanned leather, respectively. These results will build a data support for the further study of hyper-branched polymer chrome tanning auxiliaries.

Dynamics of Pulmonary Functions based on Body Mass Index Categories in Wet-Blue Leather Tannery Workers

Abstract Almost 30% of the global population is obese and overweight. In Pakistan, the latest research reveals that 28% of peoples are overweight and 16% obese. However, scarce data is available to report a relationship between obesity and pulmonary health in workers. For this reason, the current study aimed to study dynamics of pulmonary function parameters based on body mass index (BMI) categories, through a spirometer device, among wet-blue leather tannery workers. A total of 116 male tannery workers was selected as a studied population. Workers excluded who had age < 20 years, ever-smokers; respiratory disorders, cardiac illness, diabetes, and hypertension. The study was conducted between September to December 2019. Age, height, weight, and BMI were noted. The following BMI categories were used: normal-weight (18.5-24.9), overweight (25.0-29.9), and obese (≥ 30.0). The Pearson correlation test was run to determine was any linear correlation between pulmonary function parameters and BMI categories. Age, weight and BMI showed statistical differences in all BMI categories except height (P= 0.058). In obese and overweight workers, lower mean values of the pulmonary function parameters were observed compared to normal weight workers, respectively. A significant a significant linear correlation between FEV1 %, FVC % and BMI categories except for FEV1/FVC. It was concluded that obese and overweight workers might have reduced pulmonary function parameters. Future studies among tannery workers are highly recommended to find a correlation between BMI categories and pulmonary function with dust exposure. Keywords: Body mass index, Lung, Obesity, Overweight, Pakistan