"Indoor Air Quality"

Christian Monn 

You will know

- Factors that influence indoor air quality (IAQ) - important indoor sources and pollutants-Indoor/outdoor relationships -Importance of ventilation and CO2-The role of biological agents, gases and particles-Health effects: sick building syndrome (SBS ) and approach in solving problems

Background InformationIndoor air is important as we spend most of our time 

inside a building. Most outdoor pollutants are also encountered indoors.  Additionally, emissions from material, building, products and humans contribute to indoor pollution. 

In order to achieve a good indoor air quality, a well‐defined air exchange rate is needed. However, energy saving and sufficient  ventilation are often seen as antagonist. Therefore, emission from indoor material should be as low as possible and fresh air is mainly needed to remove CO2 and odors. Ventilation is often controlled according to the CO2 concentrations.

The most important indoor pollutants are VOC, particles and biological agents. When indoors, reactions between VOC and other components may occur.

Health effects in buildings (e.g. Sick Building Syndrome) may have multiple factors, such as emission of chemical and biological agents but also physical (e.g. noise), organizational and psychological stressors. A multi‐ disciplinary view is needed.

Goals

1. Indoor sourcesSources:We look at following sources... from:

Outdoors: NO2, Ozone, PM, etc. 

Indoors: 

‐ All outdoor pollutants are also found indoors..‐ Material‐ emission from the building and materials 

+ activities (cooking, cleaning, hoovering)‐ Human emissions: CO2, odor, human‐VOC (sweat, breath)

Sources for indoor pollution

groundRadon

Building material

Indoor..Paintings, gluesCarpet, solventsground

Outdoor airGases, particulate matter

naturalPollen fungi/spores Furniture,

Electronic devices

humansCO2odorsbacteriaactivity

vent

ilatio

n

1. Indoor Air QualityPurpose of good indoor air quality: .. As we spend a large proportion of our time..

Goal of a good indoor air quality:‐ well‐being

‐ prevention of symptoms and diseases

‐ working efficiency

Health: influencing factors

chemicals

biologicals

Physical factors

Occupational psychology

Interdisciplinary

Ventilation “dilemma”                  

Energy saving   <‐>  good air quality

Good sealingSmall air supply Sufficient fresh air supply

Removal of bad airEnergy loss

low emission materials ventilation primarily for removal of CO2, odors

Ventilation and Indoor Air

natural ventilation

window

Air exchange rate (Vol) per hr:0.1 to 0.5Windows open: 3.. 5

Mechanical ventilation (HVAC) Heating, Ventilation, and Air Conditioningsystems

Heating/CoolingAir ExchangeHumidification

WorkplaceComfort ventilationMinergie

Air exchange rate (Volume) per hr :0.3 to 5 ..10

‐ Good and adequate filters needed!

Ventilation rate (liter/second x person) PD=  Percentage dissatisfied (perceived)

Subjective judgment vs. measured parameter

‐CO2: important indicator of indoor air quality (standards, ventilation regulation)

ma

IAQ ‐ subjective judgment 

Quelle. Heizung und Lüftung (Handbuch)

CO2 ‐ Comfort, Odor

Threshold level for disturbing/annoying level is at CO2‐concentration up to 1‘500 ppm = 0.15 Vol.%  

ETH Studie, 80er Jahre

odor

int

ensi

ty

CO

2

„Pettenkofer Number“:up to 1’000 ppm CO2 is„acceptable“

OLF‐ Concept

Emission:

1 person (fresh cloths/shower):

1 olf

Concentration in the room:

1 decipol

10l/sec (air exchange rate)

Ole Fanger/ Olfactometry: humans are the «sensors»

Perceived air quality

Perc

enta

gedi

ssat

isfie

d

Application 5-7min

- CO2 and indoor air quality: why and when is CO2 used as an indoor air qualityparameter? ………………………………………………………………………………………………….

…………………………………………………………………………………………………..-How is air exchange rate defined? …………………………………………………………………………………………………..

…………………………………………………………………………………………………..- 10 persons are present in a lecture room (size 10m x 10m x 6m= 600 m3). There is no airexchange. Calculate the indoor CO2 (and O2) concentration after one hour! Air exchange lung: 10 Liter/min (0.6 m3/hr) p.P.

Air O2: 21%= 210 000 ppmCO2: 0.04%= 400 ppm

Exhaled: O2: 18% = 180 000 ppmCO2: 3.5%= 35’000 ppm

CO2=………… ppmO2=……. ……. ppm ………….%

2. Biological factors

The most important biologicals («non pathogens») indoors are• bacteria + endotoxins (cell wall of gram negative bacteria)

• fungal spores: mold

• pollen  

• house dust mites

•(Virus) direct risk of acute disease

Indoor/outdoor

0

100

200

300

400

500

Bakterien Pilzsporen

KBE

m-3

indooroutdoor

findings from 5 flats/apartments:

bacteria: indoors > outdoorsMold/spores: outdoors > Indoors

Units: CFU/m3

Colony forming units percubic meter of air

Air sample on agar plates counts of the CFU

Quelle: DA B. Flückiger, ETH

CFU

m-3

Spores

Cladosporium: 3-5 m Alternaria: 18-80 m Penicillium: 2-8 m

Fungal spores, mold

House dust mites

Growth: in house dust of homes< 1500 m

Feed: skin shed, organic material, sufficient humidity

Allergenic material: from faeces

Mites found :

Bed, pillow, carpet, sofa etc.

Intake: by airways and lung: inhalation of excrements in suspended house dust

size= 0.4 mm

problems in homes, humidity/ condensation

growth of mold

Cold and humid wall Cold wall, behind  cupboard, no ventilation

walls with water condensation

Quellen: Internet Raumluft

3. Human emissions) 

Biological, chemical and particulate emissions!

‐ «microbiome»: specific bacterial spieces compositionfor each individual… 

‐ Chemical emissions VOC:

‐ Particulate matter: 

sheds skin, hair, etc.

‐ surrounded of an individual «personal cloud»..

3. Human emissions) 

Breath: acetone, isporene, acetone, dimethyl sulphide, ethanol, hydrogen sulphide, isoprene, methanol, methyl mercaptan

Skin: Butanol, acetic acid, acetic acid butyl esterPentadiene decanal, geranyl acetone, heptanal, nonanal, octanal, 6‐MHO (methyl‐heptane‐one)

Head/Scalp: decal‐acetone

Plus: ”microbiome…” 

4. Gaseous pollutantsFlüchtige Kohlenwasserstoffe (VOC) Sources indoors

Building materials, furniture and devicesVOC,  particles

Outdoor airozone, nitrogen dioxide (NO2)

Formaldehyde"classic indoor pollutant":  1970s, 80s, present in media

‐ Formaldehyde is used within pressed flake boards (Spanplatten) as glue and solvent and for conservation etc.

‐ carcinogenic; but negligible < 0.1 ppm

Labels*: use of small amounts HCOH, better sealing 

New cases 2007: schools etc.

fixed in a wrong way + drilled hole etc.

* low emission flake board

Volatile Organic Compounds VOCstype Boiling point °C example

Very volatile: VVOC

< 0 to 50‐100 Formaldehyde

Volatile: VOC 50‐100 to 240‐260 Solvents

Semi volatileSVOC

240‐260 to 380‐400 Plastic softener (Phthalate), Polychlorinated biphenyls PCB

Particle bound organic matter POM

> 380 Biocides

Time‐course of indoor concentrations (after renovation, new construction): VVOC high peaks in the first days/weeks, not persistentVOC moderate peaks, temporally persistentSVOC, POM lower peaks, but temporally persistentnote: POM in dust and settled dust! children playing on the floor..

Frequently found indoor VOCsCompound source

aromatics: toluene, o‐,p‐,m‐Xylene

Benzene

Paintings, solvents, paint.outdoors

Alcohols: 1‐Butanol Building material, secondary product

Aldehydes: Nonanal (C‐9)

Benzaldehyde

Odor!

Degradation products, reaction product

Glycol ethers: 1,2‐Propandiol Solvent in paints

Terpenes: a‐pinene, Limonene Wood, cleaners

Aliphatic CH: Hexane, Decane, Undecane, Tetradecane etc.

Solvents

Formaldehyde Wood parts – glues

Measurement Tenax tube, pump

SECO, R.Reiser

Air sample &and «surface emission» sample

officesurfac

eoutdoor

s

VVOC 50 2 4

Aldehyde 27 9.5 5.8

Aromates 18 2.9 17

Alcanes (>Decan) 309 1913 3.3

Glykolether 38 35 1.0

Acid ester 71 358 1.1

Analysis VOC (GC/FIS/MS)Chromatogram

D8-Toluene

short Alkanes

Toluene

Aromatische

LimoneneAlkanes n > 10

Ozone indoors

Summer: high ozone concentrations outdoors

Ozone penetrates indoors and reacts withVOC

e.g. „natural material" (wood), Limonene, d‐Carene, alpha Pinene from wood material

or in cleaning material: 

very reactive molecules, interacting with ozone

Ozone indoors

Oxidation ‐ therefore: transformation of molecules, formation of radicals

Radicals are highly reactive species; irritation on mucous membranes

Ozone + VOC:  strong irritation of eyes, mucous membrane

Endo ozonide, "stable" (> 10 min) at indoor temperatures

‐PinenLimonen

Sek. Limonen‐Endo‐ozonidSecondary limonene endo‐ozonide

O OO

5. Particulate matterSize fractions

0.1 1 10 Micrometer

PM10

A

0.01

E

PM2.5ultrafine

Nano

Indoor particles

Sources:

‐ Re‐suspension! Activity: walking, cleaning etc.‐ Use of candles

‐ Workplace: special sources‐ Smoking‐ Outdoor air: i/o ratio!

Filtering: in mechanical ventilation systems

Case example particles

Influence of outdoor air

Indoor/outdoor‐relationship:

With indoor activity > 1Without indoor activity (reference) <1

contrast: for gas:activity No influence

Quelle: Monn et al., ETH

Indoor particles and smoking

0

50000

100000

150000

200000

25000016

:00

16:3

0

17:0

0

17:3

0

18:0

0

18:3

0

19:0

0

19:3

0

20:0

0

20:3

0

21:0

0

21:3

0

22:0

0

22:3

0

Zeit

# Pa

rtic

les

/ cm

3

Ultrafine Particles

smoking: RNo smoking: NR

Lokal BQuelle Ph.Kindler Prakt. SECO

Review 5-7min

- upon which criteria are VOCs defined? What are the most important groups? ………………………………………………………………………………………………….

…………………………………………………………………………………………………..- If ventilation in summer is high and ozone is indoors: what happens? …………………………………………………………………………………………………..

…………………………………………………………………………………………………..- Which parameters can be measured by looking at particles?……………………………………………………………………………………………….…

……………………………………………………………………………………………………- What are the main sources of indoor pollutants?…………………………………………………………………………………………………….

6. Health: Sick‐Building‐Syndrome

‐ so‐called „Sick Building Syndrome (SBS)“ („Krankes‐Gebäude‐Syndrom“)

‐ a higher percentage (>25%) of people complain about one or more symptoms

‐ Building‐Related Symptoms (BRS): well‐defined disease related to the building (gebäudebezogene Symptome)

Type of symptomsWHO definition Sick Building Syndrome (SBS) Symptoms

Irritation eyes, nose, throat, skin

Dryness Mucous membranes, skin

Inflammation Red skin, throat, Mucous membranes

Infections In airways, coughGeneral/non‐specific

Sore throat, irritation

Nervous system tiredness, lethargy, dizziness, headache, nausea, etc.

Perception odor, taste

Case example‐ questionnaire

SECO, C.Monn 35

Wie oft hatten Sie in den letzten drei Monaten eine oder mehrere der folgenden Beschwerden? (Bitte geben Sie zu jedem Symptom eine Antwort)

NIE 1

Eher selten

Gelegentlic

h

Eher oft

Sehr oft

Glaubedies hädem Arzusamm

JA S4 Müdigkeit.......................... S5 Schweregefühl im Kopf ... S6 Kopfschmerzen .....................

2. Umgebungsbedingungen an ihrem Arbeitsplatz. Wie häufig kamen in den letzten drei Monaten folgende Bedingungen an ihrem Arbeitsplatz vor? Bitte beantworten Sie die Fragen für jede Zeile)

Nie

1

Eher

selten 2

Gelegentlich

3

Eher oft

4

Sehstän

5

U1Zugluft ....................................................

U2 zu hohe Raumtemperatur .

U3 wechselnde Raumtemperatur............ .......

e.g. Andersson et al.,MM 040

3 Dimensions

environment

symptoms

Work‐organisation/psychology

bad ventilation

pollution

K. Andersson, 2014

Air quality standard indoors

Switzerland: no air quality standards indoors for homes/ apartments. Exception: formaldehyde (BAG)

‐ IA standards for workplaces: OEL (MAK values)

‐ Standard/Norm for indoor CO2 for mechanically ventilated rooms (workplaces, homes)

‐ «Reference»/ and ”Richtwerte” values and for specific VOCs «Erfahrungswerte» from statistical data bases 

scientific experience is needed for assessing Indoor Air Quality (IAQ)

Summary

What to know about «indoor air»?:

‐ Large proportion of the classis outdoor pollutants are also present indoors! (see: indoor/outdoor ratio). In addition, biological agents and volatile organic compounds (VOC) are typical indoor “pollutants”.

Some special factors indoors:

‐ CO2 (exhaled air) as marker for indoor air quality (incl. odors) and ventilation (for human emissions only!)

‐ Ventilation / air exchange rate: removes bad indoor pollutants, but may increase indoor loads from «bad» outdoor pollutants ( good filtrationneeded in mechanical ventilation systems!)

‐ Indoor «health»: sick building syndrome (multifactorial, non specific, more than 25%of people suffering from symptoms): approach step‐wise: Questionnaires, measurements, etc.

‐ Biological materials: bacteria: released by humans, sufficient ventilation needed.Fungal spores (humidity problem). Mechanical ventilation: maintenance needed!

Indoor/Outdoor ratios of pollutantsPollutant Ratio indoor /

outdoorcomments

NO2 0.3- 0.8 + gas cooking!! ratio >1O3 0.1- 0.4

0.8

> 1

Short – high i peaks withopen windows)(old) Photocopiers (sometimes >1)

CO 0.1- 0.5PM10 0.5-0.8 Smoking >> 1PM2.5 Around 1 Smoking >> 1Formaldehyde indoors >>

outdoorsIf special source indoors

VOC Indoors >> outdoors

Multiple indoor sources! (building materialias, user material, etc.)

Bacteria Indoors > outdoors From Human emissionFungal spore Indoors < outdoors when humidity damage or contaminated

ventilation system i > o