Indoor air quality in health clubs: Impact of occupancy and type of performed activities on exposure levels

Assessment of indoor air quality in health clubs: insights into (ultra)fine and coarse particles and gaseous pollutants

Introduction

Exercising on regular basis provides countless health benefits. To ensure the health, well-being and performance of athletes, optimal indoor air quality, regular maintenance and ventilation in sport facilities are essential.

Methods

This study assessed the levels of particulate, down to the ultrafine range (PM10, PM2.5, and particle number concentration in size range of 20-1,000 nm, i.e., - PNC20-1000 nm), gaseous pollutants (total volatile organic compounds - TVOCs, CO2, and O3) and comfort parameters (temperature - T, relative humidity - RH) in different functional spaces of health clubs (n = 8), under specific occupancy and ventilation restrictions.

Results and Discussion

In all HCs human occupancy resulted in elevated particles (up to 2-3 times than those previously reported), considering mass concentrations (PM10: 1.9-988.5 μg/m3 PM2.5: 1.6-479.3 μg/m3) and number (PNC 1.23 × 103 - 9.14 × 104 #/cm3). Coarse and fine PM indicated a common origin (rs = 0.888-0.909), while PNC showed low-moderate associations with particle mass (rs = 0.264-0.629). In addition, up to twice-higher PM and PNC were detected in cardiofitness & bodybuilding (C&B) areas as these spaces were the most frequented, reinforcing the impacts of occupational activities. In all HCs, TVOCs (0.01-39.67 mg/m3) highly exceeded the existent protection thresholds (1.6-8.9 times) due to the frequent use of cleaning products and disinfectants (2-28 times higher than in previous works). On contrary to PM and PNC, TVOCs were higher (1.1-4.2 times) in studios than in C&B areas, due to the limited ventilations combined with the smaller room areas/volumes. The occupancy restrictions also led to reduced CO2 (122-6,914 mg/m3) than previously observed, with the lowest values in HCs with natural airing. Finally, the specific recommendations for RH and T in sport facilities were largely unmet thus emphasizing the need of proper ventilation procedures in these spaces.

A review on indoor environmental quality in sports facilities: Indoor air quality and ventilation during a pandemic

Because of COVID-19, the indoor environmental quality (IEQ) in sports facilities has been a concern to environmental health practitioners. To develop an overall understanding of the available guidelines and standards and studies performed on IEQ in sports facilities, an extensive literature study was conducted, with the aim of identifying: (1) indicators that are being used to assess IEQ in different sports facilities; (2) indicators that are potentially interesting to be used to assess indoor air, in particular; (3) gaps in knowledge to determine whether sports facilities are safe, healthy and comfortable for people to stay and perform their activities. The outcome indicates that most current standards and previous investigations on IEQ in sports facilities mainly focused on dose-related indicators (such as ventilation rate), while building-related indicators (such as ventilation regime) and occupant-related indicators (such as IEQ preferences) were rarely considered. Little attention is given to the fact that ventilation systems may play an important role in the air quality of the location, and few investigations have been performed on the transmission of SARS-CoV-2. This study recommends more research into both occupant and building-related indicators as well as cross-modal effects between various IEQ factors for developing future standards on sports facilities.

Proxy methods for detection of inhalation exposure in simulated office environments

BACKGROUND

Modern health concerns related to air pollutant exposure in buildings have been exacerbated owing to several factors. Methods for assessing inhalation exposures indoors have been restricted to stationary air pollution measurements, typically assuming steady-state conditions.

OBJECTIVE

We aimed to examine the feasibility of several proxy methods for estimating inhalation exposure to CO2, PM2.5, and PM10 in simulated office environments.

METHODS

In a controlled climate chamber mimicking four different office setups, human participants performed a set of scripted sitting and standing office activities. Three proxy sensing techniques were examined: stationary indoor air quality (IAQ) monitoring, individual monitoring of physiological status by wearable wristband, human presence detection by Passive Infrared (PIR) sensors. A ground-truth of occupancy was obtained from video recordings of network cameras. The results were compared with the concurrent IAQ measurements in the breathing zone of a reference participant by means of multiple linear regression (MLR) analysis with a combination of different input parameters.

RESULTS

Segregating data onto sitting and standing activities could lead to improved accuracy of exposure estimation model for CO2 and PM by 9-60% during sitting activities, relative to combined activities. Stationary PM2.5 and PM10 monitors positioned at the ceiling-mounted ventilation exhaust in vicinity of the seated reference participant accurately estimated inhalation exposure (adjusted R² = 0.91 and R² = 0.87). Measurement at the front edge of the desk near abdomen showed a moderate accuracy (adjusted R² = 0.58) in estimating exposure to CO2. Combining different sensing techniques improved the CO2 exposure detection by twofold, whereas the improvement for PM exposure detection was small (~10%).

SIGNIFICANCE

This study contributes to broadening the knowledge of proxy methods for personal exposure estimation under dynamic occupancy profiles. The study recommendations on optimal monitor combination and placement could help stakeholders better understand spatial air pollutant gradients indoors which can ultimately improve control of IAQ.

A review of indoor Gaseous organic compounds and human chemical Exposure: Insights from Real-time measurements

Gaseous organic compounds, mainly volatile organic compounds (VOCs), have become a wide concern in various indoor environments where we spend the majority of our daily time. The sources, compositions, variations, and sinks of indoor VOCs are extremely complex, and their potential impacts on human health are less understood. Owing to the deployment of the state-of-the-art real-time mass spectrometry during the last two decades, our understanding of the sources, dynamic changes and chemical transformations of VOCs indoors has been significantly improved. This review aims to summarize the key findings from mass spectrometry measurements in recent indoor studies including residence, classroom, office, sports center, etc. The sources and sinks, compositions and distributions of indoor VOCs, and the factors (e.g., human activities, air exchange rate, temperature and humidity) driving the changes in indoor VOCs are discussed. The physical and chemical processes of gas-particle partitioning and secondary oxidation processes of VOCs, and their impacts on human health are summarized. Finally, the recommendations for future research directions on indoor VOCs measurements and indoor chemistry are proposed.

Assessment of Individual-Level Exposure to Airborne Particulate Matter during Periods of Atmospheric Thermal Inversion

Air pollution exposure is harmful to human health and reducing it at the level of an individual requires measurements and assessments that capture the spatiotemporal variability of different microenvironments and the influence of specific activities. In this paper, activity-specific and general indoor and outdoor exposure during and after a period of high concentrations of particulate matter (PM), e.g., an atmospheric thermal inversion (ATI) in the Ljubljana subalpine basin, Slovenia, was assessed. To this end, personal particulate matter monitors (PPM) were used, worn by participants of the H2020 ICARUS sampling campaigns in spring 2019 who also recorded their hourly activities. ATI period(s) were determined based on data collected from two meteorological stations managed by the Slovenian Environmental Agency (SEA). Results showed that indoor and outdoor exposure to PM was significantly higher during the ATI period, and that the difference between mean indoor and outdoor exposure to PM was much higher during the ATI period (23.0 µg/m3) than after (6.5 µg/m3). Indoor activities generally were associated with smaller differences, with cooking and cleaning even having higher values in the post-ATI period. On the other hand, all outdoor activities had higher PM values during the ATI than after, with larger differences, mostly >30.0 µg/m3. Overall, this work demonstrated that an individual-level approach can provide better spatiotemporal resolution and evaluate the relative importance of specific high-exposure events, and in this way provide an ancillary tool for exposure assessments.

Tent versus Mask-On Acute Effects during Repeated-Sprint Training in Normobaric Hypoxia and Normoxia

Repeated sprint in hypoxia (RSH) is used to improve supramaximal cycling capacity, but little is known about the potential differences between different systems for creating normobaric hypoxia, such as a chamber, tent, or mask. This study aimed to compare the environmental (carbon dioxide (CO₂) and wet-globe bulb temperature (WGBT)), perceptual (pain, respiratory difficulty, and rate of perceived exertion (RPE)), and external (peak and mean power output) and internal (peak heart rate (HRpeak), muscle oxygen saturation (SmO₂), arterial oxygen saturation (SpO₂), blood lactate and glucose) workload acute effects of an RSH session when performed inside a tent versus using a mask. Twelve well-trained cyclists (age = 29 ± 9.8 years, VO₂max = 70.3 ± 5.9 mL/kg/min) participated in this single-blind, randomized, crossover trial. Participants completed four sessions of three sets of five repetitions × 10 s:20 s (180 s rest between series) of all-out in different conditions: normoxia in a tent (RSNTent) and mask-on (RSNMask), and normobaric hypoxia in a tent (RSHTent) and mask-on (RSHMask). CO₂ and WGBT levels increased steadily in all conditions (p < 0.01) and were lower when using a mask (RSNMask and RSHMask) than when inside a tent (RSHTent and RSNTent) (p < 0.01). RSHTent presented lower SpO₂ than the other three conditions (p < 0.05), and hypoxic conditions presented lower SpO₂ than normoxic ones (p < 0.05). HRpeak, RPE, blood lactate, and blood glucose increased throughout the training, as expected. RSH could lead to acute conditions such as hypoxemia, which may be exacerbated when using a tent to simulate hypoxia compared to a mask-based system.

Quantification and source characterization of volatile organic compounds from exercising and application of chlorine-based cleaning products in a university athletic center

Humans spend approximately 90% of their time indoors, impacting their own air quality through occupancy and activities. Human VOC emissions indoors from exercise are still relatively uncertain, and questions remain about emissions from chlorine-based cleaners. To investigate these and other issues, the ATHLETic center study of Indoor Chemistry (ATHLETIC) campaign was conducted in the weight room of the Dal Ward Athletic Center at the University of Colorado Boulder. Using a Vocus Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (Vocus PTR-TOF), an Aerodyne Gas Chromatograph (GC), an Iodide-Chemical Ionization Time-of-Flight Mass Spectrometer (I-CIMS), and Picarro cavity ringdown spectrometers, we alternated measurements between the weight room and supply air, allowing for determination of VOC, NH₃ , H₂ O, and CO₂ emission rates per person (emission factors). Human-derived emission factors were higher than previous studies of measuring indoor air quality in rooms with individuals at rest and correlated with increased CO₂ emission factors. Emission factors from personal care products (PCPs) were consistent with previous studies and typically decreased throughout the day. In addition, N-chloraldimines were observed in the gas phase after the exercise equipment was cleaned with a dichlor solution. The chloraldimines likely originated from reactions of free amino acids with HOCl on gym surfaces.

Estimation of the Inhaled Dose of Pollutants in Different Micro-Environments: A Systematic Review of the Literature

Recently, the need to assess personal exposure in different micro-environments has been highlighted. Further, estimating the inhaled dose of pollutants is considerably one of the most interesting parameters to be explored to complete the fundamental information obtained through exposure assessment, especially if associated with a dose-response approach. To analyze the main results obtained from the studies related to the estimation of the inhaled dose of pollutants in different micro-environments (environments in which an individual spends a part of his day), and to identify the influence of different parameters on it, a systematic review of the literature was performed. The principal outcomes from the considered studies outlined that (i) exposure concentration and residence time are among the most important parameters to be evaluated in the estimation of the inhaled dose, especially in transport environments. Further, (ii) the pulmonary ventilation rate can be of particular interest during active commuting because of its increase, which increases the inhalation of pollutants. From a methodological point of view, the advent of increasingly miniaturized, portable and low-cost technologies could favor these kinds of studies, both for the measurement of atmospheric pollutants and the real-time evaluation of physiological parameters used for estimation of the inhaled dose. The main results of this review also show some knowledge gaps. In particular, numerous studies have been conducted for the evaluation (in terms of personal exposure and estimation of the inhaled dose) of different PM fractions: other airborne pollutants, although harmful to human health, are less represented in studies of this type: for this reason, future studies should be conducted, also considering other air pollutants, not neglecting the assessment of exposure to PM. Moreover, many studies have been conducted indoors, where the population spends most of their daily time. However, it has been highlighted how particular environments, even if characterized by a shorter residence time, can contribute significantly to the dose of inhaled pollutants. These environments are, therefore, of particular importance and should be better evaluated in future studies, as well as occupational environments, where the work results in a high pulmonary ventilation rate. The attention of future studies should also be focused on these categories of subjects and occupational studies.

Human exposure to air contaminants in sports environments

The aim of this review was to investigate human exposure to relevant indoor air contaminants, predictors affecting the levels, and the means to reduce the harmful exposure in indoor sports facilities. Our study revealed that the contaminants of primary concern are the following: particulate matter in indoor climbing, golf, and horse riding facilities; carbon dioxide and particulate matter in fitness centers, gymnasiums, and sports halls; Staphylococci on gymnasium surfaces; nitrogen dioxide and carbon monoxide in ice hockey arenas; carbon monoxide, nitrogen oxide(s), and particulate matter in motor sports arenas; and disinfection by-products in indoor chlorinated swimming pools. Means to reduce human exposure to indoor contaminants include the following: adequate mechanical ventilation with filters, suitable cleaning practices, a limited number of occupants in fitness centers and gymnasiums, the use of electric resurfacers instead of the engine powered resurfacers in ice hockey arenas, carefully regulated chlorine and temperature levels in indoor swimming pools, properly ventilated pools, and good personal hygiene. Because of the large number of susceptible people in these facilities, as well as all active people having an increased respiratory rate and airflow velocity, strict air quality requirements in indoor sports facilities should be maintained.

Ultrafine particles: Levels in ambient air during outdoor sport activities

Conducting aerobic activity on regular basis is recognised as one of the steps to maintain healthier lifestyle. The positive outcomes though can be outweighed if conducted in polluted atmosphere. Furthermore, the specific inhalation during exercising, which results in bypass of nasal filtration systems and deeper penetration into the respiratory system, might result in higher risks especially to pollutants such as ultrafine particles (UFP), which aerodynamic particle diameter are <100 nm. Thus, this work aims to evaluate UFP levels at sites used for conducting physical sport activities outdoors and to estimate the respective inhalation doses considering various scenarios and different physical activities. Monitoring of UFP was conducted during three weeks (May-June 2015) at four different sites (S1-S4) regularly used to conduct physical exercising. The results showed that UFP highly varied (medians 5.1-20.0 × 10³ # cm^-3) across the four sites, with the highest UFP obtained when exercising next to trafficked streets whereas S3 and S4 (a garden and city park) exhibited 2-4 times lower UFP. In view of the obtained UFP concentrations, the estimated inhalation doses ranged 1.73 × 10⁸-3.81 × 10⁸ # kg^-1 when conducting moderately intense sport activities and 1.93 × 10⁸-5.95 × 10⁸ # kg^-1 for highly intense ones. Highly intense activities (i.e. running) led to twice higher UFP exposure; children and youths (5-17 yrs old) experienced 203-267% higher doses. Considering the age- and gender- differences, estimated UFP doses of males were 1.1-2.8 times higher than of females. Finally, UFP inhalation doses estimated for walking (commuting to work and/or schools) were 1.6-7.5 times lower than when conducting sport activities. Thus to protect public health and to promote healthy and physically active lifestyle, strategies to minimize the negative impacts of air pollution should be developed and implemented.

Assessing the seasonality of occupancy number-associated CO2 level in a Taiwan hospital

This study enabled the assessment of indoor CO₂ levels and evaluated the relationship between occupancy numbers with CO₂ levels in a Taiwan hospital. The measurements were conducted over four seasons for five working days (Monday to Friday), with sampling conducted simultaneously from 09:00 am to 5:00 pm and across six locations (for spatial variability): hall (H), registration and cashier (RC), waiting area (WA), occupational therapy room (OT), physical therapy room (PT), and outdoors (O). Based on the analysis, three of the five indoor sampling sites showed significant differences in seasonal CO₂ concentrations (p < 0.0001). Based on our result, the physical therapy room had the highest level of CO₂ concentration that exceeded the IAQ standard in Taiwan Environmental Protection Agency (EPA) in all seasons, in that the number of occupants contributing to nearly 40% of the variation in CO₂ measured. Our results also showed that the indoor/outdoor (I/O) ratios of CO₂ concentration for all locations and seasons exceeded 1 in ~ 100% of those locations. The median I/O ratio at sites WA and OT was 2.37 and 2.08 during four seasons, respectively. The highest median I/O ratio was found at site PT, with a calculated range of 2.69 in spring to 3.90 in fall. The highest correlation of occupancy number and CO₂ concentration also occurred in PT which correlation coefficients were estimated at 0.47, 0.65, 0.63, and 0.40 in spring, summer, fall, and winter. The findings of the present study can be used to understand occupancy number and its effect on CO₂ levels in a hospital environment, as well as the effect of time of day (Monday to Friday) on the number of patients admitted.

Assessment of ultrafine particles in primary schools: Emphasis on different indoor microenvironments

Due to the negative health impacts, significant efforts have been directed towards investigating ultrafine particle (UFP) exposure in various indoor environments. As children spend approximately one third of their time in schools, educatory environments deserve particular attention; however, majority of past research has focused on UFP assessment in classrooms. Thus, this work aims to expand the characterization of UFP in primary schools by considering different indoor and outdoor school microenvironments and estimating inhalation doses for the respective students (6-11yrs old). Real-time UFP measurements were daily conducted (9:00-17:30) in 20 primary schools in Oporto (January-April 2014; October-February 2015) in classrooms, canteens, gyms, libraries, and concurrently outdoors. Overall, UFP concentrations showed large temporal and spatial variations. For classrooms (n = 73), median UFP (1.56 × 10³-16.8 × 10³ # cm^-3) were lower than the corresponding levels in ambient air of schools (1.79 × 10³-24.1 × 10³ # cm^-3). Outdoor emissions contributed to indoor UFP (indoor-to-outdoor ratios I/O of 0.0.30-0.85), but ventilation, room characteristics and its occupancy were identified as important parameters contributing to overall indoor UFP levels. Considering specific indoor school microenvironments, canteens were the microenvironment with the highest UFP levels (5.47 × 10³-36.4 × 10³ # cm^-3), cooking conducted directly on school grounds resulted in significantly elevated UFP in the respective classrooms (p < 0.05); the lowest UFP were found in libraries (4.45 × 10³-8.50 × 10³ # cm^-3) mostly due to the limited occupancies. Although students spend majority of their school time in classrooms (66-71%), classroom exposure was not consistently the predominant contributor to school total UFP inhalation dose (29-75%). Outdoor exposure contributed 23-70% of school dose (depending on UFP levels in ambient levels and/or conducted activities) whereas short periods of lunch break accounted for 8-40%. Therefore, when evaluating UFP exposure in educatory settings other microenvironments beyond classrooms should be an integral part of the study.

(Ultra) Fine particle concentrations and exposure in different indoor and outdoor microenvironments during physical exercising

Although regular exercise improves overall well-being, increased physical activity results in enhanced breathing which consequently leads to elevated exposure to a variety of air pollutants producing adverse effects. It is well-known that one of these ambient air contaminants is ultrafine particles (UFP). Thus, this study aimed to (1) examine exposure to particle number concentrations (PNC) in size ranging from N20-1000 nm in different sport environments and (2) estimate the respective inhalation doses across varying activity scenarios based upon the World Health Organization recommendations for physical activity. PNC were continuously monitored (TSI P-Trak™ condensation particle counter) outdoors (Out1-Out2) and indoors (Ind1-Ind2; fitness clubs) over 4 weeks. Outdoor PNC (total median 12 563 # cm^-3; means of 20 367 # cm^-3 at Out1 and 7 122 # cm^-3 at Out2) were approximately 1.6-fold higher than indoors (total median 7 653 # cm^-3; means of 11 861 # cm^-3 at Ind1 and 14 200 # cm^-3 at Ind2). The lowest doses were inhaled during holistic group classes (7.91 × 10⁷-1.87 × 10⁸ # per kg body weight) whereas exercising with mixed cardio and strength training led to approximately 1.8-fold higher levels. In order to optimize the health benefit of exercises, environmental characteristics of the locations at which physical activities are conducted need to be considered.