A systematic review of ventilation conditions and airborne particulate matter levels in urban offices.

Many working activities are carried out in office buildings that are located in urban areas. Several studies have shown that these workplaces are likely to present poor indoor environmental quality (IEQ) due to inadequate ventilation rates, compromised thermal comfort conditions, and/or high concentration of air pollutants, such as particulate matter. This study aimed to review ventilation conditions, based on carbon dioxide (CO2 ) concentrations, and indoor airborne particulate matter (PM2.5 and PM10 ) levels assessed in offices worldwide. The approach carried out in this work followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six databases (Scopus, Web of Science, PubMed, Inspec, Science Direct, and Dimensions) were used to search for peer-reviewed articles on the subject of IEQ, in particular, those reporting data for the levels of CO2 and particulate matter in offices, published during the last decade. Firstly, 394 records were identified, resulting in 23 articles included in the review after the screening process and the implementation of eligibility criteria. Based on the results and considering the mean concentration reported, office environments present, in general, acceptable ventilation conditions (mean: 665 ppm). However, the few cases of studies that reported CO2 values exceeding 1000 ppm identified situations of high occupancy density and inadequate operation of heating, ventilation, and air conditioning (HVAC) systems as the unequivocal causative factors. In turn, PM2.5 and PM10 seemed to be IEQ parameters that are even more critical to be tackled in offices, with the reported overall mean values (36 and 63 µg/m3 ) exceeding the current World Health Organization (WHO) guidelines (15 and 45 µg/m3 ). The highest aerosol concentrations were typically found in naturally ventilated buildings and were mostly associated with the influence of high levels of particles introduced indoors through the outdoor air. Overall, measures for improving IEQ in offices toward promoting healthy and safe environments for workers include strategies to periodically control IEQ, ensure the adequate percentage of fresh air and maintenance of the mechanical ventilation systems (operation, maintenance, and air filtration efficiency), and adjust occupancy to the room dimensions and ventilation conditions.

Airborne bacterial and fungal concentrations and fungal diversity in bedrooms of infant twins under 1 year of age living in Porto.

Exposure to airborne microorganisms has been linked to the development of health detriments, particularly in children. Microbial pollution can constitute a relevant health concern indoors, where levels of airborne microorganisms may be specially increased. This work aimed to characterize the airborne bacterial levels, and fungal concentration and diversity to which twins are exposed in their bedrooms (n = 30) during the first year of life. Bacterial and fungal levels varied widely across the studied bedrooms, with 10% of the rooms presenting values exceeding the national limit for both indoor bacterial and fungal counts. Cladosporium was the predominant genera, but Penicillium, Aspergillus, Alternaria, Trichoderma and Chrysonilia were also identified in the samples collected. In addition, two toxicogenic species, A. flavus and T. viride, were identified at counts that exceeded the established limit (12 CFU/m3) in 3 and 7% of the bedrooms surveyed, respectively. Based on indoor-to-outdoor concentration ratios, outdoor air seemed to be the main contributor to the total load of fungi found indoors, while airborne bacteria appeared to be mainly linked to indoor sources. Higher indoor nitrogen dioxide levels were negatively correlated with indoor fungi concentrations, whereas particulate matter and volatile organic compounds concentrations were associated with an increase in fungal prevalence. In addition, rooms with small carpets or located near outdoor agriculture sources presented significantly greater total fungal concentrations. Multiple linear regression models showed that outdoor levels were the single significant predictor identified, explaining 38.6 and 53.6% of the Cladosporium sp. and total fungi counts, respectively. The results also suggest the existence of additional factors contributing to airborne biologicals load in infants' bedrooms that deserve further investigation. Findings stress the need for investigating the existence of declared interactive effects between chemical and biological air pollutants to accurately understand the health risk that the assessed levels can represent to infants.

Assessment of CO2 and aerosol (PM2.5, PM10, UFP) concentrations during the reopening of schools in the COVID-19 pandemic: The case of a metropolitan area in Central-Southern Spain.

Public health authorities have been paramount in guaranteeing that adequate fresh air ventilation is promoted in classrooms to avoid SARS-CoV-2 transmission in educational environments. In this work it was aimed to assess ventilation conditions (carbon dioxide, CO2) and suspended particulate matter (PM2.5, PM10 and UFP) levels in 19 classrooms - including preschool, primary and secondary education - located in the metropolitan area of Ciudad Real, Central-Southern Spain, during the school's reopening (from September 30th until October 27th, 2020) after about 7 months of lockdown due to COVID-19 pandemic. The classrooms that presented the worst indoor environmental conditions, according to the highest peak of concentration obtained, were particularly explored to identify the possible influencing factors and respective opportunities for improvement. Briefly, findings suggested that although ventilation promoted through opening windows and doors according to official recommendations is guaranteeing adequate ventilation conditions in most of the studied classrooms, thus minimizing the risk of SARS-CoV-2 airborne transmission, a total of 5 (26%) surveyed classrooms were found to exceed the recommended CO2 concentration limit value (700 ppm). In general, preschool rooms were the educational environments that registered better ventilation conditions, while secondary classrooms exhibited the highest peak and average CO2 concentrations. In turn, for PM2.5, PM10 and UFP, the concentrations assessed in preschools were, on average about 2-fold greater than the levels obtained in both primary and secondary classrooms. In fact, the indoor PM2.5 and PM10 concentrations substantially exceeded the recommended limits of 8hr-exposure, established by WHO, in 63% and 32% of the surveyed classrooms, respectively. Overall, it is expected that the findings presented in this study will assist the establishment of evidence-based measures (namely based on ensuring proper ventilation rates and air filtration) to mitigate preventable environmental harm in public school buildings, mainly at local and national levels.

Indoor environmental quality in households of families with infant twins under 1 year of age living in Porto.

Exposure to air pollution in early years can exacerbate the risk of noncommunicable diseases throughout childhood and the entire life course. This study aimed to assess temperature, relative humidity (RH), carbon dioxide (CO2) and monoxide (CO), particulate matter (PM2.5, PM10), ultrafine particles, nitrogen dioxide (NO2), ozone (O3), formaldehyde, acetaldehyde and volatile organic compounds (VOC) levels in the two rooms where infant twins spend more time at home (30 dwellings, Northern Portugal). Findings showed that, in general, the worst indoor environmental quality (IEQ) settings were found in bedrooms. In fact, although most of the bedrooms surveyed presented adequate comfort conditions in terms of temperature and RH, several children are sleeping in a bedroom with improper ventilation and/or with a significant degree of air pollution. In particular, mean concentrations higher than recommended limits were found for CO2, PM2.5, PM10 and total VOC. Additionally, terpenes and decamethylcyclopentasiloxane were identified as main components of emissions from indoor sources. Overall, findings revealed that factors related to behaviors of the occupants, namely related to a conscientious use of cleaning products, tobacco and other consumer products (air-fresheners, incenses/candles and insecticides) and promotion of ventilation are essential for the improvement of air quality in households and for the promotion of children's health.

Comprehensive assessment of the indoor air quality in a chlorinated Olympic-size swimming pool.

Elite swimmers and swimming pool employees are likely to be at greater health risk due to their regular and intense exposure to air stressors in the indoor swimming pool environment. Since data on the real long-term exposure is limited, a long-term monitoring and sampling plan (22 non-consecutive days, from March to July 2017) was carried out in an indoor Olympic-size pool with a chlorine-based disinfection method to characterize indoor environments to which people involved in elite swimming and maintenance staff may be exposed to. A comprehensive set of parameters related with comfort and environmental conditions (temperature, relative humidity (RH), carbon dioxide (CO2) and monoxide and ultrafine particles (UFP)) were monitored both indoors and outdoors in order to determine indoor-to-outdoor (I/O) ratios. Additionally, an analysis of volatile organic compounds (VOC) concentration and its dynamics was implemented in three 1-hr periods: early morning, evening elite swimmers training session and late evening. Samplings were simultaneously carried out in the air layer above the water surface and in the air surrounding the pool, selected to be representative of swimmers and coaches/employees' breathing zones, respectively. The results of this work showed that the indoor climate was very stable in terms of air temperature, RH and CO2. In terms of the other measured parameters, mean indoor UFP number concentrations (5158 pt/cm3) were about 50% of those measured outdoors whereas chloroform was the predominant substance detected in all samples collected indoors (13.0-369.3 µg/m3), among a varied list of chemical compounds. An I/O non-trihalomethanes (THM) VOC concentration ratio of 2.7 was also found, suggesting that, beyond THM, other potentially hazardous VOC have also their source(s) indoors. THM and non-THM VOC concentration were found to increase consistently during the evening training session and exhibited a significant seasonal pattern. Compared to their coaches, elite swimmers seemed to be exposed via inhalation to significantly higher total THM levels, but to similar concentrations of non-THM VOC, during routine training activities. Regarding swimming employees, the exposure to THM and other VOC appeared to be significantly minimized during the early morning period. The air/water temperature ratio and RH were identified as important parameters that are likely to trigger the transfer processes of volatile substances from water to air and of their accumulation in the indoor environment of the swimming pool, respectively.

Predicting health risk from exposure to trihalomethanes in an Olympic-size indoor swimming pool among elite swimmers and coaches.

Disinfection by-products (DBP) such as trihalomethanes (THM) are formed when chlorine and bromine interact with natural organic materials in chlorine-treated swimming pools. Epidemiological evidence demonstrated an association between exposure to swimming pool environment and adverse health effects. Therefore, this study aimed to assess carcinogenic and non-carcinogenic risk of long-term exposure of elite swimmers and their coaches. In an Olympic-size indoor chlorinated swimming pool, THM levels were determined in water (21-69 µg/L), in the boundary layer above the water surface (59-397 µg/m3), and in the air surrounding the pool (28-390 µg/m3). These values were used to predict multi-pathway chronic daily intake (CDI), cancer risk (CR) and hazard index (HI). Oral and dermal CDI for swimmers were 2.4 × 10-6 and 2.0 × 10-8, respectively. The swimmers' inhalation CDI (1.9 × 10-3 mg/kg/day) was estimated to be sixfold higher than levels obtained for coaches (3.3 × 10-4 mg/kg/day). According to guidelines, the HI was acceptable, but CR exceeded the recommended limit for both, coaches (CR: 5.5 × 10-7-8.5 × 10-5; HI: 6.5 × 10-4-1 × 10-1) and swimmers (CR: 1.4 × 10-5-3.6 × 10-4 HI: 1.6 × 10-2-4.3 × 10-1). Our findings provide further support to the need to develop comprehensive guidelines to safeguard the health of individuals involved in elite swimming.