Personal exposure to ultrafine particles and responsible sources

Personal exposure to ultrafine particles and responsible sources

International Centre for Indoor Environment and Energy Department of Civil Engineering

Technical University of Denmark

Gabriel Bekö

100 µm 2 nm Largest particle: 100 μm (10^-4 m)

Smallest particle: 2 nm (0.002 μm or 10^-9 m) 5 orders of magnitude

Size range of airborne particles

Ultrafine particles: <100nm (0.1 µm) Fine particles: 0.1 – 2.5 µm (PM2.5)

Coarse particles: >2.5 µm

Particles indoors

Thatcher et al. Aerosol Sci Technol, 2003

• particles emitted indoors (cooking, smoking, resuspension, textile fibers, skin flakes)

• ambient particles infiltrated indoors

• particles formed indoors through reactions of gas-phase precursors emitted both indoors and outdoors

(ozone/terpene reactions; Ozone/skin oil reactions

Humans emit particles

Humans replace their outer skin layer every 2 to 4 weeks

Milstone, J Derm Sci, 2004

One person emits:

• 200,000 – 600,000 skin flakes/min

• 30 – 90 mg skin flakes/h

Deposition model

Most Penetrating Particle Size 0.1 – 0.5 µm

Ultrafines: Able to reach the smaller airways of the lower respiratory tract Large surface area per unit mass

Toxic and carcinogenic substances

- polycyclic aromatic hydrocarbons (PAHs) - metals

Health Effects

Subjective responses:

• Irritation of eyes, nose, throat

• Dry skin sensation

• Odor and taste symptoms

• Headache

• Fatigue

• Dizziness

• Reduced capability to concentrate

• Reduced productivity

Health effects

Exception: Pollution from unvented burning of biofuels

• Epidemiological studies of mortality and morbidity show associations primarily with particles indoors generated outdoors.

• Poor correlations were found between ambient PM2.5 and personal exposure

• Is the ambient PM the most representative measure for exposure to PM?

• Health effects of indoor generated particles insufficiently documented

Riley et al., ES&T 2002; Chen & Zhao, Atmos Environ, 2011 WHO – causes of death

World Health Statistics: 2016, Mortality due to air pollution by disease type, p. 75

Globally in 2012

• Household Air Pollution from cooking with unclean fuels … caused 4.3 million deaths

• Outdoor air pollution caused 3 million deaths

• Among children under 5,

Household Air Pollution estimated to cause half of all pneumonia

deaths

WHO on Household Air Pollution

Unvented biomass burning – Developing countries

Sources of ultrafine particles

Outdoor sources Indoor sources

Which one do we inhale more of?

0 100000 200000 300000 400000 500000

1 10 100 1000

Mobilty equivalent diameter (nm)

frying sausages omelette, 3 events average

frying veg wok peeling tangerines peeling oranges frying onions dinner party + candles

frying

average background no active source

Courtesy: A. Wierzbicka, Lund U.

Number size distribution at peak concentrations from different activities in the apartment

Particles / cm3

0 3000 6000 9000 12000

1 10 100 1000

Mobility equivalent diameter (nm)

aparment occupancy time apartment average apartment no sources house average supermarket restaurant school A school B

Courtesy: A. Wierzbicka, Lund U.

Average number size distributions for various indoor environments

Particles / cm3

 Inspection, Questionnaires

 CO₂, T, RH in bedroom and living room

 2-weeks collection of settled dust on EDC for endotoxin, bacteria, mold and fungi

 48-hour measurement of UFPs (10-300nm) in living room

Measurements in 56 Copenhagen homes

47768

10384 8154

0 10000 20000 30000 40000 50000 60000

Mean

Particle conc. (#/cm3)

Occupied awake Occupied asleep UnOccupied

Average PN concentration

Occupancy

Nights, unoccupied periods

Area under the curve = integrated exposure

Contribution of indoor sources

(%)

Location

59 USA

19 - 42 Beijing

47 USA

50-80 USA

58-69 Canada

66 Sweden

65 Denmark

Indoor sources explain about 65% of the total daily residential exposure

0 500,000 1,000,000 1,500,000 2,000,000 2,500,000 3,000,000 13

57 119 1315 1719 2123 25 2729 3133 3537 3941 4345 4749 51 5355

Daily Integrated Exposure (#/cm3.h/d)

Background Indoor Sources

Contribution of background and indoor sources

Time

Apportionment

N=28; Contr.=58%

N=37; Contr.=30%

Contribution of peaks/events

Bekö et al., ES&T 2013

Candle burning

Occurring in 50% of homes, on average 5 times a week, 2.3 hours a day

Causing elevated PN levels on average over 5.7 hours per day, 8.2 hours after a candle event.

Responsible for 70% of the total exposure from indoor sources 60% of total residential exposure

(incl. background from outdoor sources)

0 100,000 200,000 300,000 400,000 500,000 600,000 700,000

Soy wax. Organic, GMO free Palm wax. organic Pure candle wax Paraffin tealight candle Liquid paraffin Candle wax stick light Paraffin Candle wax Soy wax in a glass. Organic, GMO free Scented soy wax in a glass. Organic, GMO free

Average particle concentration (#/cm³)

UFP from candles

UFP from candles

0 50,000 100,000 150,000 200,000 250,000 300,000 350,000

0:00 0:30 1:00 1:30 2:00 2:30 3:00 3:30

Particle number conc (1/cm3 )

Time (min)

Glass Paraffin

0 20,000 40,000 60,000 80,000 100,000 120,000 140,000

0:00 0:30 1:00 1:30 2:00

Particle number conc (1/cm3 )

Time (min)

Glass Paraffin first time use

subsequent use

steady sooting

blown out

open window 5 min

steady sooting

0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 800,000 900,000

Glass

Paraffin Glass Palm

Wax Glass Soya

Wax Glass

Stearin 60mm Powder Pressed

Par

Stearin60mm 22mm Extruder

Par

Stearin22mm Particle number conc (1/cm3 )

Mean PN conc. – 1-hr steady burn (subsequent use)

UFP from candles

 Inspection, Questionnaires

 CO₂, T, RH in bedroom and living room

 48-hour measurement of UFPs (10-300nm) in living room

 Personal monitoring of UFP exposure + GPS

Measurements in 60 homes / 59 occupants

Concentration x Time

Personal monitor with GPS

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000

Median PN concentration (#/cm3 ) ^HomeActive transport Passive transport Other indoor - building Other outdoor

12.5 (52.2%)

0.5(1.9%) 0.8(3.2%)

9.6(40.1%)

0.85(3.5%)

0 2 4 6 8 10 12 14

Average time spent (h/d)

HomeActive transport Passive transport Other indoor - buildings Other outdoor

Contribution of microenvironments

Location Median contrib.

to total (%)

In the home 50

Away from home 50

Active transport 1.8

Passive transport 5.4

Other indoor - buildings 41.5

Other outdoor 3.3

All indoors – buildings 90.6 All indoors incl. passive trans. 95.4

All outdoors 4.6

~50% of total exposure occurs in the home

Where do we get most of it from?

Bekö et al., Atm Env 2015

Where do YOU inhale most of it during the day?

0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 office worker

biking postman bus driver retired person at

home retired person active

Daily Integrated Exposure (cm^-3h/d)

Home

Active transport Passive transport Other indoor - buildings Other outdoor

winter 2011/12 spring 2013

The role of home

Average exposure within the home

 Microvascular function, Lung function (FVC, FEV1), Biomarkers (inflammation; blood, urine, saliva) Winter 2012

 Association between residential exposure and lung function, markers of inflammation and diabetes

 When stratified, association confirmed for candle related exposure, not for cooking related exposure

Lung function and systemic effects

Spring 2013

 Exposure outside the home (but not in the home)

associated with microvascular function and markers of inflammation

 Traffic-generated UFP may be more potent regarding health effects than UFP from indoor sources

• Intervention (filtration) studies: conflicting results on the impact of UFP on microvascular function, lung function or biomarkers of inflammation

 Never leave your home!

 Stop that cooking frenzy – grab fast food!

 Remember that not all winter days are Christmas days!

 Remember to ventilate, esp. when indoor sources are present!

Summary & Recommendations for a healthier life

Thank you!

• A significant fraction (50%) of the total personal daily integrated exposure to UFP occurs within the home. Indoor sources significantly contribute to this exposure.

• Exposures indoors also dominate away from home. Outdoor sources may be responsible for a large fraction of this exposure.

• Outdoor particles may have more health effects than indoor generated particles, but Indoor UFP are likely to have important adverse effects.