Study of particle number size distributions at Azadi terminal in Tehran, comparing high-traffic and no traffic area

Indoor and outdoor air quality in street corner kiosks in a large metropolitan area

Poor air quality in workplaces constitutes a great concern on human health as a good fraction of our time is spent at work. In Greece, very unique workplaces are the street corner kiosks, which are freestanding boxes placed on sidewalks next to city streets and vehicular traffic, where one can find many consumer goods. As such, its employees are exposed to both outdoor and indoor air pollutants. Very few studies have examined the occupational exposure of kiosk workers to air pollutants, and thus the magnitude of this unique indoor and outdoor exposure remains unknown. The objective of this study is to investigate and compare the levels of indoor and outdoor particulate matter (PM10 and PM2.5), ultrafine particles (UFPs) and black carbon (BC) in different kiosks located in Athens, Greece, in urban-traffic and urban-background environments. Continuous measurements of the above-mentioned pollutants were carried out on a 24-h basis over 7 consecutive days at three kiosks from September to October 2019. Indoor PM10 concentrations in the urban kiosk ranged from 19.0 to 44.0 μg/m3, PM2.5 values ranged from 14.0 to 33.0 μg/m3, whereas BC concentrations ranged from 1.2 to 7.0 μg/m3 and UFPs from almost 9.5 to 47.0 × 103 pt/cm3. Outdoor PM10 and PM2.5 measurements ranged from 29.0 to 59.0 μg/m3 and from 22.0 to 39.0 μg/m3, respectively. BC outdoor concentrations ranged from 1.1 to 2.2 μg/m3. The mean hazard quotient (HQ) for PM10 (4.9) and PM2.5 (4.7) among all participants was >1. The health risk of exposure to PM10 and PM2.5 was found to be at moderate hazard levels, although in some cases we observed HQ values higher than 10 due to high PM10 and PM2.5 concentrations in the kiosks. Overall our study indicates that people working at kiosks can be exposed to very high concentrations on particulate pollution depending on a number of factors including the traffic that strongly depends on location and the time of the day.

Exposure to air pollution and risk of ovarian cancer: a review

OBJECTIVES

Exposure to air pollution has destructive health consequences and a potential role in ovarian cancer etiology. We conducted a systematic review of the studies assessing the associations between ovarian malignancy and exposure to air pollutants.

CONTENT

The included studies were categorized based on types of measured ambient air pollutants, including particulate matter (five studies), gases (two studies), air pollutant mixtures (eight studies), and traffic indicators for air pollution (only one study). Because of the heterogeneity of quantitative data of the reviewed studies, we qualitatively reviewed the air pollution role in ovarian cancer risk with representing incidence and/or the mortality rate of ovarian cancer in related with air pollution. Nine studies were ecological study design. Except for one, all studies confirmed a positive correlation between exposure to ambient air pollution (AAP) and increased ovarian cancer risks.

SUMMARY

We concluded that prolonged air pollution exposure through possible mechanisms, estrogen-like effects, and genetic mutations might affect ovarian tumorigenesis. This research surveyed the limitations of the previous studies, including issues with ambient air pollution surveillance and assessing the exposure, determining the air pollution sources, data analysis approaches, and study designs.

OUTLOOK

Finally, the authors provide suggestions for future environmental epidemiological inquiries on the impact of exposure to ambient air pollution on ovarian malignancy.

Traces of black carbon sources before and after the Covid-19 outbreak in Tehran, Iran

The concentration of black carbon was measured in four sites of the industrial and high-traffic metropolis of Tehran with different land uses. Then, the contribution of biomass and fossil fuels in the emission of this pollutant was modeled using the Aethalometer model. The possible locations of important sources of black carbon dissemination were projected using PSCF and CWT models, and the results were compared in the two periods before and after the Covid-19 outbreak. Temporal variations of black carbon illustrated that BC concentration decreased in the period after the onset of the pandemic in all studied areas, and this decline was more explicit in the traffic intersection of the city. Diurnal changes of BC concentration indicated the significant impact of the application of the law banning night traffic of motor vehicles in reducing the BC concentration in this period, and probably the reduction of HDDV traffic has played the most important role in this reduction. The results related to the share of BC sources indicated that black carbon emissions are affected by an average of about 80% of fossil fuel combustion and wood combustion interferes with about 20% of BC emissions. Finally, speculations were made about the possible sources of BC emission and its urban scale transport using PSCF and CWT models, which indicated the superiority of the CWT model in terms of source segregation. The results of this analysis were further utilized to surmise black carbon emission sources based on the land use of receptor points.

PAHs pollution in the outdoor air of areas with various land uses in the industrial city of Iran: distribution, source apportionment, and risk assessment

Shahryar city regions with various land uses had their outdoor air concentrations of PM_2.5-bound PAHs determined. Totally, 32 samples were taken - eight samples from the industrial region air (IS), eight samples from the high-traffic urban regions air (HTS), eight samples from the air of commercial regions (CS), and eight samples from residential areas (RS), which were analyzed by GC-MS. According to the study's findings, in the outdoor air of IS, HTS, CS, and RS, there were mean ƩPAHs concentrations of 23.25 ± 20.22, 38.88 ± 26.53, 6.97 ± 4.26, and 4.48 ± 3.13 ng/m³, respectively. As comparison to CS and RS, mean concentration of ƩPAHs in samples from HTS and IS was substantially greater (p < 0.05). Using the Unmix.6 receptor model, sources of PAHs in the air of Shahryar were allocated. The model's results show that 42% of PAHs come from diesel vehicles and industrial activities, 36% from traffic and other transportation sources, and 22% from heating sources and coal burning. The carcinogenicity suffering resulting from exposure to PAHs was as follows: This value for children of the ingestion, inhalation pathways and dermal contact is (1.90 × 10^-6-1.38 × 10^-4), (5.5 × 10^-11-2.67 × 10^-9) and (2.36 × 10^-6-1.72 × 10^-4), respectively. Also, for adults were (1.47 × 10^-6 - 1.07 × 10^-4), (1.14 × 10^-10 - 5.27 × 10^-9) and (3.68 × 10^-6- 2.87 × 10^-4), respectively. In general, the analyzed region's carcinogenicity risk estimates fell within the range of acceptable limit.

Attributable risk and economic burden of pneumonia among older adults admitted to hospital due to short-term exposure to airborne particulate matter: a time-stratified case-crossover study from China

Many studies have proven the relationship between air pollutants and respiratory diseases, but few studies have assessed the impacts of air particulate matter exposure on older patients with pneumonia. This study aimed to reveal the impacts of short-term exposure to air particulate matter on the daily number of older adult patients hospitalized due to pneumonia and calculate the economic costs attributable to this exposure. We collected inpatient data from 9 city hospitals in Sichuan Province, China, from January 1, 2018, to December 31, 2019, and calculated odds ratios and 95% confidence intervals using a time-stratified case-crossover study design and an attributable risk model to calculate the economic burden due to particulate matter pollution. It was found that for every 10 μg/m³ increase in PM_2.5 and PM₁₀ concentrations, the daily number of older adult pneumonia inpatients increased by 1.5% (95% CI: 1.010-1.021) and 1.0% (95% CI: 1.006-1.014), respectively. Those 65 ~ 79 years old were more susceptible to air particulate pollutants (P < 0.05). During the study period, the total hospitalization costs and out-of-pocket expenses attributable to PM_2.5 and PM₁₀ exposure were 44.60 million CNY (6.22%) and 16.03 million CNY (6.21%), respectively, with PM_2.5 being the primary influencing factor. This study revealed the relationship between particulate matter pollution and pneumonia among older adults. The role of policies to limit particulate matter concentrations in reducing disease burden among older adults can be further explored.

Associations between long-term exposure to ambient fine particulate pollution with the decline of kidney function and hyperuricemia: a longitudinal cohort study

Evidence of associations between ambient fine particulate matter (PM_2.5) and risks of decline of kidney function and hyperuricemia is limited. We aimed to investigate the associations between long-term exposure to PM_2.5 with decline of kidney function and hyperuricemia in China. We conducted a two-stage study based on China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2015. Cox proportional hazard regression models and restricted cubic splines were used to evaluate the associations of PM_2.5 with risks of decline of kidney function and hyperuricemia. Latent class trajectory models (LCTM) were used to identify trajectories of PM_2.5 from 2011 to 2015 in the sensitivity analysis. A total of 9760 participants were included in baseline analysis, and 5902 participants were in follow-up analysis. PM_2.5 was associated with the risks of decline of kidney function [hazard ratio (HR): 2.14; 95% confidence interval (CI): (1.03, 4.44)] and hyperuricemia [HR 1.40 (95% CI: 1.10, 1.79)] in the second quartile group versus the lowest quartile group of PM_2.5. We also observed nonlinear relationships between PM_2.5 and the risks of the decline of kidney function and hyperuricemia (P_non-linear < 0.001). In sensitivity analysis, four trajectory groups were identified. "Maintaining a high PM_2.5" [odds ratio (OR): 2.20; 95%CI: (1.78, 2.73)] and "moderately high starting PM_2.5 then steadily decreased" [OR (95%CI): 5.15 (1.55, 16.13)] were associated with hyperuricemia risk, using "low starting PM_2.5 then steadily decreased" trajectory as reference. In conclusion, improved air quality is essential for prevention of decline of kidney function and hyperuricemia.

The effect of PM2.5-related hazards on biomarkers of bronchial epithelial cells (A549) inflammation in Karaj and Fardis cities

Fine particles (especially PM2.5 particles) in ambient air can cause irreversible effects on human health. In the present study, seasonal variations in toxicity PM2.5 (cell viability and release of pro-inflammatory cytokines) were exposed human lung cells (A549) to concentrations of PM2.5 samples in summer (sPM2.5) and winter (wPM2.5) seasons. Cells were separately exposed to three concentrations of PM2.5 (25, 50, and 100 μg/mL) and three times (12 h, 1 and 2 days). We evaluated cell viability by MTT assay [3- (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium bromide] and liberation of pro-inflammatory cytokines (interleukin-6 and interleukin-8) by the ELISA method. The toxicological results of this study showed that increasing the concentration of PM2.5 particulates and contact time with it reduces cell viability and increases inflammatory responses. Seasonal cytotoxicity of PM2.5 particles in high-traffic areas at summer season compared to winter season was lower. The lowest percent of viability at 2 days of exposure and 100 μg/mL exposure in the winter sample was observed. Also, PM2.5 particles were influential in the amount of interleukins 8 and 6. The average release level of IL-6 and IL-8 in the cold season (winter) and the enormous exposure time and concentrations (2 days-100 μg/mL) was much higher than in the hot season (summer). These values were twice as high for winter PM2.5 samples as for summer samples. The compounds in PM2.5 at different seasons can cause some biological effects. The samples' chemical characteristics in two seasons displayed that the PMs were diverse in chemical properties. In general, heavy metals and polycyclic aromatic hydrocarbons were more in the winter samples. However, the samples of wPM2.5 had a lower mass quota of metals such as aluminum, iron, copper, zinc, and magnesium. Concentrations of chromium, cadmium, arsenic, mercury, nickel, and lead were more significant in the sample of wPM2.5.

Potential cytotoxicity of PM2.5-bound PAHs and toxic metals collected from areas with different traffic densities on human lung epithelial cells (A549)

Laboratory and epidemiological researches have indicated that ambient air particulate matter have a plays critical role in causing diseases. The current research evaluated the chemical attributes of PM2.5 in the ambient air of the cities of Karaj and Fardis and determined its toxicological effects on human lung epithelial cells (A549). In the study city, 16 points were selected from the two high-traffic and low-traffic points for sampling. A sampling of ambient air was carried out in spring, summer, autumn, and winter 2018-19. Air sampling was performed for 24 h according to the EPA-TO/13A guidelines. To analyze of toxic metals and polycyclic aromatic hydrocarbons (PAHs), ICP-OES and GC-MS were used, respectively, and for cell toxicity analysis, an ELISA reader was used. Then from SPSS, Excel and R software were used for statistical analysis. The results of the current study indicated that the concentration of PAHs carcinogenic in the autumn season in high-traffic stations was the highest and equal to 9.3 ng/m3, and in the spring season in the low-traffic stations, it was the lowest and equal to 5.82 ng/m3. In general, during the period of study, Heavy metals including Zn, Fe, Pb, Cu, and Al had the highest concentration compared to other metals. However, Hg, Cr, As, Pb, Cu, Cd, and Zn were higher concentration in the winter and autumn seasons than in the spring and summer seasons. Cell viability measurements by using MTT showed that low-traffic and high-traffic stations had the highest toxicity in autumn season compared to other seasons. (p < 0.05). In general, high-traffic stations had the highest toxicity than low-traffic stations. The general conclusion of the present study was that PM2.5-bound PAHs and toxic metals, due to their high concentration, were toxic pollutants in air for residents of Karaj and Fardis. Also, the high concentration of PM2.5 caused the mitochondrial activity of A549 cells to stop and this stop was more significant in cold seasons and high-traffic areas.

Spatial distribution and health risk of exposure to BTEX in urban area: a comparison study of different land-use types and traffic volumes

Many previous studies have investigated BTEX concentrations in urban areas; however, the available evidence on the association of different land-use types and BTEX concentrations is still scarce. In this study, the BTEX concentrations were measured and compared in different land-use types and traffic volumes of Mashhad metropolis, Iran. Sampling was conducted in summer and winter of 2018 based on NIOSH 1501 method in six land-use types, including Residential, Commercial/official, Industrial, Greenspace, Transportation, and Tourism. The spatial autocorrelation model was used to investigate the emission pattern. The Monte Carlo simulation technique and sensitivity analysis were used to assess the health risk of exposure to BTEX compounds. The median [interquartile range (IQR)] of benzene, toluene, ethylbenzene m-xylene, o-xylene and total BTEX concentrations based on overall mean were 4 (2.23), 8.37 (4.48), 1.2 (1.46), 0.89 (2.59), 0.8 (1.73) and 17.7 (8.19) µg/m³, respectively. Benzene and toluene had clustered emission patterns (z-score > 1.96). Exposure to benzene in the study area had a carcinogenic risk for inhabitants. The concentration of BTEX compounds was significantly different based on land-use type. The maximum and minimum concentrations of BTEX were observed in Transportation and Greenspace land uses, respectively. The BTEX concentrations in summer were significantly higher than in winter, and traffic had a significant effect on BTEX concentrations. Overall, our results supported a significant relationship between land-use type and BTEX concentrations in the urban area. Moreover, ambient benzene concentration had a carcinogenic risk potential for inhabitants of study area.

Health risk assessment and source apportionment of heavy metals in atmospheric dustfall in a city of Khuzestan Province, Iran

The heavy metals in the atmospheric particulate matters are now considered a risk for humans and the environment. The purpose of this study was to assess the concentration, source apportionment, and health risk of heavy metals in atmospheric dustfall in Dezful City of Khuzestan Province, Iran. The dustfall samples were collected from five locations every month for one year (2018-2019). The heavy metals ( lead (Pb), cadmium (Cd), chromium (Cr), iron (Fe), and nickel (Ni)) contents of dustfall samples were determined by ICP-OES. The monthly mean of dustfall for five sampling locations was 22.81 ± 21.9 ton.km- 2.month- 1. The mean concentrations of the examined heavy metals were assessed as Fe > Cr > Ni > Pb > Cd. The highest enrichment level belonged to Cd (59.35 ± 128.18) and all heavy metals had enrichment levels beyond 10. The HI (Hazard Index) values were less than one and there was no significant non-carcinogenic risk due to these heavy metals. For children, Ni showed the most HI with a value of 0.205. The calculations demonstrate that the obtained values of cancer risk in both groups are less than the acceptable range (10- 6 to 10- 4). The PMF (Positive Matrix Factorization) results indicated four main sources of pollutants, namely, vehicular exhaust, industrial, road dust, and nonferrous smelting. The results of the study revealed that industrial activities and traffic play crucial roles in increasing the heavy metals contamination of dustfall in Dezful City.

Airborne particulate matter in Tehran's ambient air

In recent decades, particulate matter (PM) concentrations in Tehran have exceeded the World Health Organization's (WHO) guideline on most days. In this study, a search protocol was defined by identifying the keywords, to carry out a systematic review of the concentrations and composition of PM in Tehran's ambient air. For this purpose, searches were done in Scopus, PubMed, and Web of Science in 2019. Among the founded articles (197 in Scopus, 61 in PubMed, and 153 in Web of Science). The results show that in Tehran, the annual average PM₁₀ exceeded the WHO guidelines and for more than 50.0% of the days, the PM_2.5 concentration was more than WHO 24-h guidance value. The PM concentration in Tehran has two seasonal peaks due to poorer dispersion and suspension from dry land, respectively. Tehran has two daily PM peaks due to traffic and changes in boundary-layer heights; one just after midnight and the other during morning rush hour. Indoor concentrations of PM10 and PM2.5 in Tehran were 10.6 and 21.8 times higher than the corresponding values in ambient air. Tehran represents a unique case of problems of controlling PM because of its geographical setting, emission sources, and land use. This review provided a comprehensive assessment for decision makers to assist them in making appropriate policy decisions to improve the air quality. Considering factors such as diversity of resources, temporal and spatial variations, and urban location is essential in developing control plans. Also future studies should focus more on PM reduction plans.

Characterization, possible sources and health risk assessment of PM2.5-bound Heavy Metals in the most industrial city of Iran

Air pollution associated with particulate matters results in different types of disease including allergy, lung destruction, heart failure, and related problems. This study has been designed and performed to examine the concentration of PM_2.5-bound heavy metals, risk assessment, possible sources and effect of meteorological parameters on 17 sites of the air of the most industrial city of Iran (Karaj) in 2018-19. For this purpose, four samples were taken from every point of Karaj air over one year using a pump (Leland Legacy (SKC)) with flow rate of 3 L/min on PTFE filter for 24 h. Overall, 68 samples of PM_2.5-bound heavy metals were collected. Note that during the sampling, atmospheric parameters including temperature, pressure, humidity, and wind speed were regularly recorded using PHB318 portable device. In examining the chemical composition of these particles, the concentration of metals (Al-Zn- Ar-Cd-Cr-Cu-Fe-Hg-Mn-Ni-Pb) was determined after digestion of the collected samples and through injection into ICP-OEC device. The results indicated that the mean annual concentration of PM_2.5 particles range from 21.84 to 72.75 µg/m³. The mean concentration of heavy metals lied within the range of 25.63 to 336.27 ng/m³. Among heavy metals, the maximum concentration belonged to aluminum (277.95 ng/m³) and iron (336.27 ng/m³), which are known as elements with a ground source (sources such as car fuels, exhaust gases, decorative materials, batteries, indoor smoking, the paint used for painting walls, erosion and corrosion of rubber of cars). Meanwhile, there was a positive relationship between heavy metals and temperature(r: 0.418, p < 0.019), pressure (r: 0.184, p < 0.0.402), as well as wind speed (r: 0.38, p < 0.017), while an inverse relationship was observed with relative humidity (r: -0.219, p < 0.018). The ecological risk of the metals calculated was very notable, with the maximum environmental risk being related to cadmium in children (6.61) and manganese in adults (0.82). The largest HQ in children and adults was associated with Cr. Finally, ILCR values for cadmium in both children (1.19 E-04) and adult (4.81 E-04) groups indicated high risk of developing cancer in humans.

Monitoring of airborne asbestos fibers in an urban ambient air of Mashhad City, Iran: levels, spatial distribution and seasonal variations

Asbestos, as with other pollutants in the air, has adverse effects on the health of human beings and animals. Today, the relationship between presence of asbestos fibers in the air breathed by humans and developing serious diseases such as lung cancer (asbestosis) and mesothelioma has been proven. The objectives of this study were to monitor the levels of asbestos fibers in ambient air of Mashhad, Iran during 2018, and to draw its Geographic Information System (GIS) distribution map for the city. In this descriptive study, 13 sampling points in Mashhad city were chosen. Sampling of asbestos was carried out for 3 hour during summer and winter at 2018. Sampling of asbestos was performed using MCE (Mixed Cellulose Ester) membrane filters (pour size 0.45 µm; diameter: 25 mm) and cassette holder and peripheral pump. The samples were the analyzed by the phase contrast microscopy (PCM) method (NIOSH7400). Also, to investigate the type of asbestos and for more accurate counting of fibers, Scanning Electron Microscopy (SEM) analysis was utilized. Meteorological parameter were recorded through portable devices. To draw the graphs, Excel, R and Arc GIS software were used. Results showed that the mean asbestos fiber concentrations were equal to 11.40 ± 2.14 and 14.38 ± 2.52 f/L in summer and winter, respectively. The maximum level of asbestos fiber was detected in the station of Baitolmoghaddas square by 26.64 ± 2.14 and 19.3 SEM f/L in winter and summer, respectively. High concentration of asbestos fiber observed in this study can be attributed to the heavy traffic, the presence of prominent industries in the vicinity of the study area, and topographic features. The results from this research recommends that suitable controlling policies should be regulated to reduce both ambient air asbestos and its adverse health endpoints in Mashhad.

Levels, sources, isotope signatures, and health risks of mercury in street dust across China

Spatial distribution and isotope signature of mercury (Hg) in street dusts across China were investigated by collecting dust samples from 14 cities and reviewing previously published data from an additional 46 cities. Potential sources of street dust and the associated health risks to humans were also assessed. The total Hg (THg) concentrations in street dust ranged from 0.020-39.1 mg kg^-1 with an average of 0.433 ± 0.185 mg kg^-1 in the 60 cities. Street dust samples collected from 14 cities were characterized by slightly negative δ²⁰²Hg (-0.61 ± 0.92‰) and near-zero Δ¹⁹⁹Hg (-0.03 ± 0.08‰) values, and coal combustion and industrial activities were estimated to be the major sources of Hg in street dust. The estimated average probable daily intake (PDI) of THg from street dust exposure for adults and children (1.36E-03 and 1.27E-02 μg d^-1 kg^-1, respectively) were comparable to their respective exposures via rice consumption in China. Children being exposed to THg in dust is a major concern in mercury mining areas (e.g., Wangshan and Xunyang), and may also be a concern in cities with major coal-based industries and nonferrous metal smelting. Results from this study suggest that exposure to street dust is not a primary MeHg exposure pathway in China.

Assessment of common plant parameters as biomarkers of air pollution

Air pollution is a very serious current environmental issue of human society. Large parts of countries, especially the densely populated cities, having high vehicular movement, industries, and factories, are worst affected. Biomarkers are changes in plant parameters that help in easy assessment of the environmental quality of an area at a certain time. Plants can react to different environmental stresses with the most evident responses shown by the leaves. In the present work, we have studied changes in biochemical parameters in the leaves of a mango plant (Mangifera indica), a very common plant in West Bengal, India, which were collected from four different locations in the city of Kolkata which has a high concentration of air pollutants and one control area from a rural region having a low concentration of air pollutants. It was observed that leaves which were exposed to high amounts of harmful air pollutants showed higher accumulation of molecules such as phenol, proline, malondialdehyde, and cellulose with lower amounts of chlorophyll. From this, we can observe that common environmental stress such as air pollution leads to a change in the synthesis of bioactive molecules to resist the effect of stress on the plant. Thus, from these data, it can be concluded that biochemical parameters can serve as efficient biomarkers of the air quality of an area.

The investigation of type and concentration of bio-aerosols in the air of surgical rooms: A case study in Shariati hospital, Karaj

The presence of bio-aerosols is one of the main causes of hospital infections that can be dangerous especially for immunocompromised patients. This research aimed to determine the relationship between hospital infections and surgical incision size in addition to determining the concentration and bacterial and fungal bioaerosols found in the operating rooms. This cross-sectional descriptive-analytic study was carried out in the operating rooms of Shariati Hospital in Karaj, Iran during the years 2016 and 2017. A total of 198 bacterial samples and 198 fungal samples were collected and analyzed using a passive sampling standard method (1/1/1) for 180 days. Tryptic Soy Agar (TSA) and Sabouraud Dextrose Agar (SDA) medium were used for bacterial and fungal samples, respectively. Relevant differential tests were used to determine the genus and species of bacteria and fungi such as DNase test, Bile-esculin, motility test urease test. In general, this work presents:

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The present evaluated the relationship between bioaerosols concentration and surgical incision size.

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The intraoperative concentration of bacterial and fungal bioaerosols in indoor air of the orthopedic, internal and cesarean operating rooms was significantly higher than their preoperative concentration (p-value<0.05).

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Also, there was not significant difference between the bacterial and fungal concentrations in various operating rooms) p-value<0.05).

Investigation of thermal exposure in traditional neyshabur bakeries using heat strain and physiological indices

Bakery is one of the occupations which are exposed to the high shear stress. The incidence of heat discomfort among traditional bakery workers is much more than machinery bakery. The aim of this study was to investigate the rate of heat strain index and temperature of drumhead under physical conditions in this group of workers. This cross-sectional study was conducted on 103 workers of the Bakeries in winter 2018. Heart rate and oral temperature were respectively measured using a heart rate meter and an oral thermometer. The Wet-bulb globe temperature (WBGT) index was recorded and the Heat Strain Score Index (HSSI) was completed simultaneously was used. Data obtained from this study were analyzed by comparing means, t test, and Person tests with the SPSS 20 software. The results of the assessment of WBGT, and HSSI showed that 28.69(1.41)and 15.02(2.6) percent of workers exposed to heat stress higher than permissible limits proposed by standard bodies. Also, the present study proved that the mean rate of Heat Strain indicating the presence of strain level 2. According to the results from this study, the oral temperature and drumhead were higher in workers who performed baking activity than other two groups. It is concluded that there is a significant relationship between Heat strain index and Distance of bakery floor ratio to stre.