IAQ of Swimming Pools BSCI 9170 Herman Kwok
Aug 18, 2015
Overview
• Introduction
• Applicable Air Quality Requirements
• Potential Contaminants & Source
• Presence & Concentration
• Health Effects
• Regulatory Limits
• Control
• Video
Introduction
• Pool smell does not necessarily mean facility is clean & safe
• Disinfection by-product off-gassing
• Chloramines
• Contribution to health-related problems
• Not strictly regulated
• Effective solutions
Ventilation Requirements• ASHRAE 62.1 – 2010
• WHO recommends 10L of fresh air /sec / m2 of water surface area
• Air turnover min. 40% refresh air
cfm/person L/s·person cfm/ft2 L/s·m2 #/1000 ft2 cfm/person L/s·person
Spectator Areas7.5 3.8 0.06 0.3 150 8 4 1
Swimming (Pool
and Deck)0.48 2.4 C 2
Default Values
Occupant
Density
Combined Outdoor Air
RateAir Class
Occupancy
Category
People Ontdoor
Air Rate
RP
Area Outdoor
Air Rate
RaNotes
Contaminants
• Chloramines & Trihalomethanes (THMs)
• THMs
• Formed predominantly when organic matter combines with chlorine in drinking (fresh) water
• Volatile, easily vaporizes
• U.S. Environmental Protection Agency (EPA), uptake greatest via the skin with dermal absorption accounting for 80%
Chloramines
• Disinfection byproducts
• Formed from reaction of chlorine with nitrogen products
• Sweat, urine, dirt, sunscreen, saliva and other wastes
• Chlorine dispersed in water, a rapid hydrolysis occurs
• 𝐶𝑙2 +𝐻2𝑂 → 𝐻𝑂𝐶𝑙 + 𝐻+ + 𝐶𝑙−
Powerful Oxidants
• 𝑁𝐻3 + 𝐻𝑂𝐶𝑙 → 𝑁𝐻2𝐶𝑙 + 𝐻2𝑂(monochloramine; pH = 6-8)
• 𝑁𝐻2𝐶𝑙 + 𝐻𝑂𝐶𝑙 → 𝑁𝐻𝐶𝐿2 + 𝐻2𝑂(dichloramine; pH = 5-6)
• 𝑁𝐻𝐶𝑙2 +𝐻𝑂𝐶𝑙 → 𝑁𝐶𝑙3 + 𝐻2𝑂(trichloramine; pH = <5)
Focus: Trichloramine
• Distinct chlorine odor
• Highly volatile substance
• Irritating for the breathing system, eyes and skin
• Production occurs predominantly below pH 5
• Swimming pool water will normally have a pH between pH 6.8 and 7.6
Biofilms
• Attachment of free-floating microorganisms
• Identified by the sliminess
• Moist surfaces
• Pool water surfaces, walls, bottoms, ladder rails, tank bodies, piping
• 99% of the bacteria
Presence
• Low pH – Acidic
• Trichloramine production
• Bather load increases Thicker biofilms
Greater production
• Meanwhile more chlorine reaction with ammonia, more chloramines
• pH below 4.4 or the chlorine to ammonia-nitrogen ratio becomes greater than 7.6:1, then trichloramine can form
Concentration• Fountains, sprays or slides more splashes
• Easily vaporize, hovering above the pool
• Fine aerosol reaches breathing zone
• Adopt more energy-efficient ventilation systems bad air recirculates
• Fresh water treated with monochloramine
Health Effects
• Chloramines are derivatives of ammonia, with the compound trichloramine being the most toxic
• 2 hours exposure to an average concentration of 0.490 mg/m3
– Significantly increase the levels of the alveolar surfactant associated proteins A and B
– In other words, weaken the protective nature of the surface of the lungs
U.S Centers for Disease Control and Prevention (CDC)
• May lead to difficulty in breathing, coughing, stinging eyes, red eyes, wheezing, asthma attacks, or increased sensitivity to other irritants in the environment
• Susceptible to allergens and infections such as influenza and pneumonia
• Trihalomethane 900 ppm – Dizziness, fatigue and headaches
– Typical natatorium contains only up to 0.13 ppm
– Ambient air contains up to .00005 ppm
Control
• Fresh water / air (limited)
• Always shower before entering pool
• Super-chlorination (Sodium hypochlorite (NaClO))
– ten times the normal amount of chlorine is one way to destroy chloramines
• Ozone
– more potent oxidizing agent
• Non-chlorine shock (Monosulphate)
– can release the available chlorine to free chlorine
Paddock Evacuator™ Chloramine Evacuation System
• See the Paddock Evacuator™ in action!