A numerical study of the impacts of outdoor air intake and air changes per hour on the trichloramine concentrations in a swimming pool enclosure
Bibliographic record
Abstract
Trichloramine (NCl3) is a disinfection by-product commonly found in the water and air in indoor swimming pools. The gas is associated with chronic diseases such as asthma and often causes eye and skin irritation. Due to its higher density than air, NCl3 tends to accumulate close to the water surface and above the deck. Mixing ventilation is the main ventilation strategy used in aquatic centers to maintain the NCl3 concentrations at an acceptable level. However, swimming pool halls are known to be significantly energy-intensive, mostly because of water evaporation from the basin. Consequently, building codes recommend maintaining a low airspeed above the pool and deck to minimize evaporation and to ensure swimmers’ thermal comfort. If trichloramine levels are suspected to be too high, pool managers will favor increasing the number of air changes per hour (ACH) while limiting the outdoor air (OA) intake. However, mechanical filtration systems are not designed to remove NCl3 from the airflow. Since its concentration cannot be measured directly, ventilation system parameters are often based on minimum recommendations set out in building codes and may vary in operation according to the CO2 levels in the extracted air, irrespective of the NCl3 level and its accumulation behavior. It remains unknown how the OA intake ratio affects NCl3 levels in breathing zones. This study carries out a numerical investigation of the impacts of the OA and the ACH on NCl3 concentrations in a swimming pool hall in Montreal (Canada). Results show that the minimum recommendations (OA intake and ACH) by ASHRAE are not sufficient to eliminate NCl3 accumulation and stratification in the lower breathing zones. Moreover, air recirculation mostly affects the breathing zones of standing occupants on decks and of lifeguards but has a smaller impact on the breathing zones of swimmers or people sitting on the deck. Eliminating air recirculation does not guarantee better air quality in terms of NCl3 in these breathing zones. The findings for the complex under study may be used to guide similar research in other aquatic centers and for the continuous development of building codes and air quality standards.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".