IAQ of Swimming Pools

BSCI 9170

Herman Kwok

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

Regulatory limits

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

• UV Lamps

– No risk of overdosing or by-product formation

Source Capturing

Paddock Evacuator™ Chloramine Evacuation System

• See the Paddock Evacuator™ in action!

Thank You