The present study aimed to determine the concentrations of several disinfection byproducts (DBPs), including trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs), in the public and private swimming pools in Sanandaj, Iran (n=16). Correlations between DBP levels with water quality parameters (free chlorine, pH, total organic carbon, temperature, number of swimmers, and gender of swimmers) and various DBP categories were investigated and compared. According to the results, concentrations of THMs in public and private pools were lower than the recommended limit in Iran (200 μ g/L). In addition, HAAs had the highest concentrations, followed by THMs and HANs, respectively. Among the HAAs, THMs, and HANs, trichloroacetic acid was the most dominant species, followed by chloroform and dichloroacetonitrile, respectively. DBP levels were not affected by the gender of swimmers, number of swimmers, pH, temperature, and free chlorine. However, total organic carbon showed a fairly good correlation with TTHM, THAA, and DBP levels (r=0. 45-0. 78; P<0. 05). Some correlations were also observed between various DBP categories.

Background: In the U. S., drowning is a leading cause of death for toddlers. One important layer of protection against submersion injuries and fatalities is parent or caregiver supervision. The aims of this study are to explore current supervisory behavior of caregivers, determine how caregivers view common supervision distractions, like cell phones and grilling, and identify what factors shape the quality of supervision that is given when swimming with their toddler at a swimming pool. Methods: This cross-sectional study used the MTurk online platform to survey 650 caregivers of toddlers (1-4 yrs old) about their supervision behavior, their drowning knowledge, their perceptions of arm’ s reach supervision, the water competency of their toddler, and other background information. Regression analysis was used to identify factors that predicted reported supervision behavior. Results: The average supervision behavior score for caregivers indicated an attitude between neutral and disagreement with allowing distractions for themselves while supervising their toddler in a swimming pool. High water safety knowledge and positive perceptions of arm’ s reach supervision were the biggest predictors of attentive supervision behavior. Having a home pool, higher education level, and believing their toddler had greater water competency were predictive of less attentive supervision behavior. Conclusion: Results suggest that supervision behavior while toddlers are in a swimming pool may be inadequate. Low water safety knowledge and attitudes about what constitutes quality supervision are related to pool supervision behavior and changing these may reduce drowning risk. Caregivers should be encouraged to not reduce supervision as their toddlers gain water competency and if they have a home pool.

The present experimental study reports on enhancement of heat transfer by addition of nanoparticles to the working fluid of commercial swimming pool heat exchangers under laminar flow condition. Three different concentrations of Titanium dioxide nanoparticles were added to the water as working fluid of a typical forced convective heat exchanger used to transfer heat to public swimming pools. The experimental setup is capable of measuring velocity, heat transfer rate, and temperature at different points. TiO2 nanoparticles with mean diameter of 20 nm were used. The effects of suspended nanoparticles concentration and that of Peclet number on forced convective heat transfer were investigated. It is observed that at 0.1%, 0.5% and 1% weight concentration of suspended TiO2 nanoparticles, the average convective heat transfer coefficient improved by 1.1%, 15.9% and 31.6% respectively. The coefficient is further increased at higher Peclet numbers. The efficiency of heat exchanger is evaluated for different scenarios.