Association of Morning Distribution of Real-Time Indoor Ultrafine Particulate Matter (PM2.5) Concentrations with Daily Activity Patterns of Asthmatics in South Korea : Preliminary Study Results

Abstract

Asthmatics may be more susceptible to ultrafine particulate matter (PM2.5), due to its large number of chemicals attached on it, compared to ordinary population. Acute exacerbations of RA can lead to such severe airway obstruction that mechanical ventilation is required as a lifesaving measure. Thus, knowing the risk factors for RA is important for minimizing both the need for emergency medical interventions and disruption of daily activities. And depending on patients’ degree of symptoms, acute exposure to PM2.5 can lead to severe airway obstruction. Indoor PM2.5 may be the mixture of the influx of outside air and indoor activities. Thus, understanding of the association of indoor activity pattern and variation of indoor PM2.5 level is important. The purpose of this study was to obtain the distribution of hourly indoor PM2.5 concentration in asthmatics’ houses, and to evaluate its association with their daily activity pattern. From November 2016 to November 2017, a real-time PM2.5 concentrations were measured at the livingroom of each asthmatic’s house (n=30) for 3 weeks with 1 minute intervals. At the same time, self-reported daily activity patterns, i.e., hourly proportion(%) of cooking activities, were also recorded every hour over 3 weeks for each patient. The median concentration of PM2.5 at the morning cooking time (7:00 to 10:00 am) was 30.0 ug/m3. The distribution pattern of hourly proportion of cooking activities were similar to that of PM2.5 concentration level, but there was 1 or 2 hour time lag. Spearman correlation coefficient between the hourly proportion of cooking activities and the PM2.5 concentration was 0.67 and 0.65 (p=0.072 and 0.078) at child asthmatics’ houses and 0.7 and 0.87 (p=0.233 and 0.058 for 8 O’clock and 9 O’clock) at adult asthmatics’ houses. Our real-time monitoring results demonstrated that variation of indoor morning PM2.5 concentration level was potentially associated with indoor cooking activity patterns at home.