HONO, NO2, and asthma
Description
The association between nitrogen dioxide (NO2) and asthma has been investigated. However, conventional NO2 assays measure nitrous acid (HONO) as NO2. In this trial study, we assessed exposure to indoor HONO and some air pollutants in pediatric asthma patients and examined the association between exposure and asthma symptoms. Indoor HONO and nitric oxide (NO), which are primarily generated by the combustion of certain substances, were significantly associated with asthma attacks in 2010 and 2010-2012. Outdoor NO2 was significantly associated with asthma attacks in 2012 and 2010-2012. In 2010, indoor HONO was strongly correlated with indoor NO than with outdoor NO2. Conversely, in 2012, indoor HONO was strongly correlated with outdoor NO2 and NO than with indoor NO2 and NO. Our results highlight the need for further epidemiological studies of the association between HONO and asthma symptoms using multivariate analyses to examine the role of NO2 in asthma symptoms. This study is a trial epidemiological study targeting five pediatric asthma patients per year (2010–2012) with daily self-reported asthma symptoms. Indoor HONO was collected weekly by active sampling at the subjects’ homes. Indoor NO2, NO, and O3 samples were collected weekly by passive sampling at the subjects’ homes. We used data from the Kishiwada Central Park monitoring station. The weekly concentrations of outdoor pollutants for each subject were calculated from hourly data of the monitoring station according to indoor sampling periods.