Common household activities are associated with elevated particulate matter concentrations in bedrooms of inner-city Baltimore pre-school children

Abstract

Asthma disproportionately affects inner-city, minority children in the U.S. Outdoor pollutant concentrations, including particulate matter (PM), are higher in inner-cities and contribute to childhood asthma morbidity. Although children spend the majority of time indoors, indoor PM exposures have been less extensively characterized. There is a public health imperative to characterize indoor sources of PM within this vulnerable population to enable effective intervention strategies. In the present study, we sought to identify determinants of indoor PM in homes of Baltimore inner-city pre-school children. Children ages 2-6 (n=300) who were predominantly African-American (90%) and from lower socioeconomic backgrounds were enrolled. Integrated PM(2.5) and PM(10) air sampling was conducted over a 3-day period in the children's bedrooms and at a central monitoring site while caregivers completed daily activity diaries. Homes of pre-school children in inner-city Baltimore had indoor PM concentrations that were twice as high as simultaneous outdoor concentrations. The mean indoor PM(2.5) and PM(10) concentrations were 39.5+/-34.5 and 56.2+/-44.8 microg/m(3), compared to the simultaneously measured ambient PM(2.5) and PM(10) (15.6+/-6.9 and 21.8+/-9.53 microg/m(3), respectively). Common modifiable household activities, especially smoking and sweeping, contributed significantly to higher indoor PM, as did ambient PM concentrations. Open windows were associated with significantly lower indoor PM. Further investigation of the health effects of indoor PM exposure is warranted, as are studies to evaluate the efficacy of PM reduction strategies on asthma health of inner-city children.

Figure 1. Indoor PM Concentrations in Inner-City Baltimore Homes

These box and whisker plots demonstrate the PM values measured in the homes and simultaneous ambient levels. The boxes show the interquartile ranges (IQR) and the heavy dark lines are the medians. Whiskers represent closest value within1.5X the IQR of PM values. In-home PM concentrations were significantly higher than ambient PM concentrations and in most cases. Over 75% of homes exceeded the EPA annual limit for ambient PM_2.5 and 47% of homes exceeded the annual limit for PM₁₀.

Figure 2a and 2b. Predictors of Elevated Indoor PM_2.5 and PM₁₀ Concentrations by Events over the 3-day Period

Box and whisker plots demonstrate the dose response effect seen with increased frequency of smoking, sweeping, and stove use over the 3-day monitoring period that lead to increased indoor PM levels. The median values are displayed within boxes that contain the middle 50% of PM values. The whiskers extend to the closest value within 1.5 times the interquartile range.

Figure 2a and 2b. Predictors of Elevated Indoor PM_2.5 and PM₁₀ Concentrations by Events over the 3-day Period

Box and whisker plots demonstrate the dose response effect seen with increased frequency of smoking, sweeping, and stove use over the 3-day monitoring period that lead to increased indoor PM levels. The median values are displayed within boxes that contain the middle 50% of PM values. The whiskers extend to the closest value within 1.5 times the interquartile range.