Children's personal exposure to airborne particulate matter

Personal exposure to particulate matter (PM₁₀ and PM₂.₅) for ten children aged 9 - 11 years was measured between January and September 1997 in the London Borough of Barnet. Personal, home, garden and classroom micro environmental monitoring was successfully completed for all ten children. Each child was monitored for five consecutive days during winter, spring and summer, with the exception of one child who did not complete the summer session. All children completed daily time activity diaries to provide infonnationon any activities that could potentially influence their exposure patterns. Each evening parents completed a household activity questionnaire providing information on all particle generating activities such as cooking and cleaning. Personal Environmental Monitors were used for the personal sampling and Harvard Impactors for the microenvironmental
sampling.
The children's mean personal exposure concentrations for PM₁₀ during winter, spring and summer were 69, 69 and 32 ug/m³ respectively and for PM₂.₅ 21, 24 and 15 ug/m³ respectively. The strongest and most consistent associations were found between the personal and indoor exposure concentrations. The most significant correlations were
observed between personal and home PM₁₀ with a median rs = 0.66. Classroom concentrations were the highest of all the sampled environments which could be attributed to the number of children present and the resuspension of particles. Ambient contributions of PM₂.₅ to PM₁₀ during the day were estimated to be 56%, which is comparable to other UK research. Indoor/outdoor concentrations were influenced by heating in the homes, however no significant specific particle generating activities in the home were found during the day. At night, home concentrations of PM₂.₅ appeared to be influenced by the presence of smokers.
To determine potential sources of particulate matter, analysis of a sub sample of filters was undertaken using Scanning Electron Microscopy. Within the home particle composition
was influenced by human activities predominantly; resuspended soil dust, skin flakes and fibres. The outdoor particles were predominantly biological in origin; pollen and insect debris. The composition of the personal exposure filters was a mixture of both environments and was dependant upon how much time each child spent in each of these
environments. Smooth globular particles c.2um in diameter were found on all filters and could be combustion related, possible vehicle derived or from cooking activities.
Measured data, along with the reviewed literature, provides some insight into the source apportionment of particulate matter. Analysis of questionnaire and time activity diaries
also provides information on individual children's exposure patterns. Some estimation of potential health outcomes is discussed.