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.

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.

Indoor Sources of Air Pollutants

People spend an average of 90% of their time in indoor environments. There is a long list of indoor sources that can contribute to increased pollutant concentrations, some of them related to human activities (e.g. people's movement, cooking, cleaning, smoking), but also to surface chemistry reactions with human skin and building and furniture surfaces. The result of all these emissions is a heterogeneous cocktail of pollutants with varying degrees of toxicity, which makes indoor air quality a complex system. Good characterization of the sources that affect indoor air pollution levels is of major importance for quantifying (and reducing) the associated health risks. This chapter reviews some of the more significant indoor sources that can be found in the most common non-occupational indoor environments.

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.

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

Associations between indoor air quality (IAQ) and health in sport practise environments are not well understood due to limited knowledge of magnitude of inhaled pollutants. Thus, this study assessed IAQ in four health clubs (HC1-HC4) and estimated inhaled doses during different types of activities. Gaseous (TVOCs, CO, O₃, CO₂) and particulate pollutants (PM₁, PM₄) were continuously collected during 40 days. IAQ was influenced both by human occupancy and the intensity of the performed exercises. Levels of all pollutants were higher when clubs were occupied (p < 0.05) than for vacant periods, with higher medians in main workout areas rather than in spaces/studios for group activities. In all spaces, TVOCs highly exceeded legislative limit (600 μg/m³), even when unoccupied, indicating possible risks for the respective occupants. CO₂ levels were well correlated with relative humidity (r_s 0.534-0.625) and occupancy due to human exhalation and perspiration during exercising. Clubs with natural ventilations exhibited twice higher PM, with PM₁ accounting for 93-96% of PM₄; both PM were highly correlated (r_s 0.936-0.995) and originated from the same sources. Finally, cardio classes resulted in higher inhalation doses than other types of exercising (1.7-2.6).

Indoor particulate pollution in fitness centres with emphasis on ultrafine particles

Fitness centres (FC) represent a unique indoor microenvironment. Exercising on regular basis provides countless health benefits and improves overall well-being, but if these facilities have poor indoor air quality, the respective exercisers might be subjected to some adverse risks. Considering the limited existent data, this work aimed to evaluate particulate pollution (PM_10, PM_2.5, and ultrafine particles - UFP) in indoor air of FC and to estimate the respective risks for occupants (both staff and exercising subjects). Sampling was conducted during 40 consecutive days of May-June 2014 in general fitness areas, studios and classrooms (for group activities) of four different fitness centres (FC1-FC4) situated within Oporto metropolitan area, Portugal. The results showed that across the four FC, PM₁₀ ranged between 5 and 1080 μg m^-3 with median concentrations (15-43 μg m^-3) fulfilling the limit (50 μg m^-3) of Portuguese legislation in all FC. PM_2.5 (medians 5-37 μg m^-3; range 5-777 μg m^-3) exceeded thresholds of 25 μg m^-3 at some FC, indicating potential risks for the respective occupants; naturally ventilated FC exhibited significantly higher PM ranges (p < 0.05). Similarly, UFPs (range 0.5-88.6 × 10³ # cm^-3) median concentrations were higher (2-3 times) at FC without controlled ventilation systems. UFP were approximately twice higher (p < 0.05) during the occupied periods (mean of 9.7 × 10³vs. 4.8 × 10³ # cm^-3) with larger temporal variations of UFP levels observed in general fitness areas than in classrooms and studios. Cardio activities (conducted in studios and classrooms) led to approximately twice the UFPs intakes than other types of exercising. These results indicate that even short-term physical activity (or more specifically its intensity) might strongly influence the daily inhalation dose. Finally, women exhibited 1.2 times higher UFPs intake than men thus suggesting the need for future gender-specific studies assessing UFP exposure.

Lung function and dust in climbing halls: two pilot studies

In climbing halls, high levels of dust are found because magnesia powder is used to dry hands. Concerns have been raised about possible health effects after reports from asthmatics experiencing worsening of symptoms while or after climbing. We investigated acute and sub-acute effects of climbing in dusty halls on lung function in two pilot studies. The first study examined 109 climbers before and after a climbing activity that lasted at least 1 h. In the second study, 25 climbers from different age classes participated in a 2-day climbing competition. Of these, 24 agreed to take part in our investigation, but only 22 provided valid lung function tests on both days. The climbers underwent lung function tests before the first round of the competition (in the morning), after the second round approximately 3 h later and in the morning of the second day before the competition started again. In the first study, we found acute effects, a decline in lung function immediately after the exposure, likely due to protective reflexes of the bronchial muscles and stronger declines in persons with higher exhaled nitric oxide (NO) pre-climbing. In the second study, we also expected sub-acute effects on the next day due to inflammation. On the first day of the competition (second study), dust levels at a central monitor increased over time in a linear manner. Most of the dust was in the size range between 2.5 and 10 μm and dust levels of particulate matter (PM10) reached 0.5 mg/m3. There was a decline in lung function over 24 h in persons with higher exhaled NO levels pre-exposure. All spirometric parameters were affected though the effects were not statistically significant in all cases. Younger age classes started earlier in the morning. Because of the increasing trend in dust levels we expected stronger effects with higher numbers but for the acute effects the reverse was true, possibly because younger climbers use magnesia more or with less experience thus causing higher individual exposure. No differences by age or by time of the first climb were observed for the 24-h lung function change.

Indoor aerosol size distributions in a gymnasium

In this study, an indoor/outdoor monitoring program was carried out in a gymnasium at the University of Leon, Spain. The main goal was a characterization of aerosol size distributions in a university gymnasium under different conditions and sports activities (with and without magnesia alba) and the study of the mass fraction deposited in each of the parts of the respiratory tract. The aerosol particles were measured in 31 discrete channels (size ranges) using a laser spectrometer probe. Aerosol size distributions were studied under different conditions: i) before sports activities, ii) activities without using magnesia alba, iii) activities using magnesia alba, iv) cleaning procedures, and v) outdoors. The aerosol refractive index and density indoors were estimated from the aerosol composition: 1.577-0.003i and 2.055 g cm(-3), respectively. Using the estimated density, the mass concentration was calculated, and the evolution of PM1, PM2.5 and PM10 for different activities was assessed. The quality of the air in the gymnasium was strongly influenced by the use of magnesia alba (MgCO3) and the number of gymnasts who were training. Due to the climbing chalk and the constant process of resuspension, average PM10 concentrations of over 440 μg m(-3) were reached. The maximum daily concentrations ranged from 500 to 900 μg m(-3). Particle size determines the place in the respiratory tract where the deposition occurs. For this reason, the inhalable, thoracic, tracheobronchial and respirable fractions were assessed for healthy adults and high risk people, according to international standards. The estimations show that, for healthy adults, up to 300 μg m(-3) can be retained by the trachea and bronchi, and 130 μg m(-3) may reach the alveolar region. The different physical activities and the attendance rates in the sports facility have a significant influence on the concentration and size distributions observed.

Particulate matter in the indoor and outdoor air of a gymnasium and a fronton

An indoor/outdoor monitoring programme of PM10 was carried out in two sports venues (a fronton and a gymnasium). Levels always below 50 μg m(-3) were obtained in the fronton and outdoor air. Due to the climbing chalk and the constant process of resuspension, concentrations above 150 μg m(-3) were registered in the gymnasium. The chalk dust contributed to CO3 (2-) concentrations of 32 ± 9.4 μg m(-3) in this sports facility, which represented, on average, 18 % of the PM10 mass. Here, the carbonate levels were 128 times higher than those registered outdoors. Much lower concentrations, around 1 μg m(-3), were measured in the fronton. The chalk dust is also responsible for the high Mg(2+) concentrations in the gym (4.7 ± 0.89 μg m(-3)), unfolding a PM10 mass fraction of 2.7 %. Total carbon accounted for almost 30 % of PM10 in both indoor spaces. Aerosol size distributions were bimodal and revealed a clear dependence on physical activities and characteristics of the sports facilities. The use of climbing chalk in the gymnasium contributed significantly to the coarse mode. The average geometric mean diameter, geometric standard deviation and total number of coarse particles were 0.77 μm, 2.79 cm(-3) and 28 cm(-3), respectively.