The purpose of this study is to analyze the effect of temperature and humidity on the measured Particulate Matter (PM) concentrations recorded by PMS5003T, a low-cost light scattering type measuring tool. A regression analysis was performed on the ratio of PM concentrations measured by the light scattering method and the beta-ray absorption method according to temperature and humidity in an outdoor environment. As the temperature decreased, the PM concentration ratio increased, and this tendency intensified below 0oC. As the humidity increased, the PM concentration ratio increased, but the effect was less than the temperature effect. The coefficients of determination for temperature and humidity were R2 = 0.325 and 0.003, respectively, and the effects of temperature and humidity on the measured values w ere formulated and compensated for. As a result of the compensation, R2, relative precision, accuracy and RMSE improved from 0.927 to 0.958, from 91.183% to 96.651%, from 31.383% to 74.058%, and from 13.517 μg/m³ to 6.690 μg/m³, respectively. Finally, results from this study indicate that the reliability of the low-cost light scattering type PM sensor can be improved by applying the temperature and humidity compensation method.

Since 1974, the urban subway has been used as a major form of public transportation in Seoul, Korea. The air quality in the subway environment depends on the introduction of air pollutants from roadway air and its generation is caused by subway operation in the tunnel. In the subway tunnel, PM10 concentration was monitored from March 8 to 15, 2018 and from March 26 to 28, 2018, and compared with concentrations that are routinely monitored at the subway concourse and the nearest roadside air quality monitoring station (RAQMS). Overall PM10 concentration at the concourse was similar to that of the RAQMS. However, PM10 concentration in the tunnel was significantly higher than those of the subway concourse and RAQMS, and showed distinct diurnal variation caused by train operation. The dominant peak concentrations were highly correlated with the number of train operations per hour. The minimum PM10 concentration was observed between 2 am to 5 am when the train was not operated. This was similar to that of the RAQMS. Although the diurnal variation of the PM10 concentration at the concourse is not significant, the overall trend is similar to that in the tunnel.

The urban railway system is a convenient public transportation system, as it carries many people without increasing traffic congestion. However, air quality in urban railway environments is worse than ambient air quality due to the internal location of the source of air pollutants and the isolated space. In this paper, characteristics of particulate matter (PM) pollution in urban railway environments are described from the perspective of diurnal variation, chemical composition and source apportionment of PM. PM concentrations in concourse, platform, passenger cabin, and tunnel are summarized through an analysis of 34 journal articles published in Korea and overseas. This information will be helpful in developing effective policies to reduce PM pollution in urban railway environments.

While the air quality of public facilities such as daycare centers is managed by law, the management of air quality in residential buildings is not mandatory. For this reason, air quality in an apartments has not been well surveyed. In this study, we investigated the influence of cooking and ventilation on the indoor air quality in an apartment. Continuous measurements were performed using real-time monitoring instruments from June 9 to 17, 2014 in Seoul, Korea. A CO2 meter was used to measure CO2 concentration and temperature. A portable aerosol spectrometer (0.25-32 μm), a nanoparticle aerosol monitor (10-1,000 nm), and an aethalometer (total suspended particulate, black carbon) were also used. During the measurement period, ventilation and cooking activities were observed 8 and 10 times, respectively. In 5 of the observed cases, both activities were done simultaneously. During the ventilation, CO2 concentration and temperature were decreased; however, particle concentrations were increased. When cooking was done, particle concentration was increased in some cases; however, CO2 concentration and temperature were unchanged. Combined cased CO2 concentration and temperature were decreased and particle concentrations were increased.

The number of children who use day-care centers is increasing. Most indoor air quality (IAQ) management has been based on daily average pollutant concentrations measured once a year. A more comprehensive management of IAQ is needed to protect children’s health from air pollutants in day-care centers. In this study, we investigated the weekly variation of air pollutant concentrations in a nursing room of a day-care center located at the roadside for a week in June of 2014. Average concentrations of CO2, PM10, black carbon, and total surface area of lungdeposited particles during nursing time of the day-care center were 510 ppm, 27.8 μg/m3, 1.87 μg/m3, and 30.6 μm2/cm3, respectively, with a similar diurnal pattern shown on weekdays.

Secondary air pollution can be caused by aerosol formation through reactions of ozone and volatile organic compounds (VOCs) emitted from household products used in the indoor environment. In this study, we investigated the potential for aerosol production during the reactions of ozone and VOCs emitted from a home insecticide, a popular commercial product extracted from natural ingredients, in a 1-m³ reaction chamber. The major chemical component of the test product was prallethrin, which has very high efficacy of mosquito and housefly elimination. Toluene, α-pinene, cymene, d-limonene, α-terpinene, and α-thujone were also identified as constituents of the insecticide. Injected ozone concentrations of 50, 100, and 200 ppb generated particle mass concentrations, corrected for wall loss and air exchange loss, of 7.3, 33.1, and 40.0 μg/m³, respectively, after a 4-h reaction time. These concentrations are lower than those generated by an air freshener in a previous study under the same experimental conditions. It was concluded that the home insecticide tested had the potential to initiate secondary aerosol formation under ozone exposure due to the biogenic VOCs it contained.