Indoor sources of ultrafine particles

M. Dennekamp, S. Howarth, A. Seaton

Research output: Contribution to journalArticleOtherpeer-review


Ultrafine particles may be responsible for causing the effects of particulate air pollution. We have used a TSI Incorporated Model 3934 scanning mobility particle sizer (SMPS) to measure the particle number concentration (PNC) of particles 10-100 nm diameter. Outdoor and indoor PNC were measured daily from December 1998 until February 1999. Daily mean outdoor concentrations averaged 1.34 x 104 ± 1.09 x 104 particles/cm3 (lowest daily average count 1.0 x 103, highest 4.9 x 104 particles/cm3). The mean indoor/outdoor concentration ratio when outdoor concentration were higher than 5 x 103 particles/cm3 was c65%(N=65). At concentrations lower man 5 x 103 particles/cm3 the ratio was close to 1 (N=18). Cooking experiments were performed in a laboratory equipped with gas and electric cookers, without mechanical ventilation. The windows were closed during all measurements. When four gas rings were fully turned on, PNC rose rapidly. Peak PNC within 20 minutes varied between 1.5 and 3.8 x 105 particles/cm3. Two hours after the gas rings were turned off, particle number concentrations were not back to baseline levels. When four electric rings were turned fully on, PNC over 5 minutes rose to between 1.6x105 and 2.5x105 particles/cm3. In both cases, the particles grew in size in time. The highest initial PNC was observed in the size range 20-25nm diameter, while 45 minutes after the rings had been turned off, the highest PNC was observed in particles in the size range 35-40nm diameter. Ultrafine particle exposure during cooking will contribute to the total exposure of individuals. Whether this is biologically important is subject to further studies.

Original languageEnglish
Pages (from-to)A29-A29
Number of pages1
Issue numberSUPPL. 3
Publication statusPublished - 1 Dec 1999
Externally publishedYes

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