| The concentration of particulate matter in indoor air is one of the important indexes to measure indoor air quality.People spend most of their lifetime in indoor environment.And the concentration of particulate matter and human health are closely related.Therefore,it has great academic value and theoretical significance to deeply investigate the concentration levels of PM10,PM2.5,and PM1.0 in indoor environments,the sources of pollution,influencing factors,and the correlation between indoor and outdoor particulate concentrations to improve the environment and protect human health.This paper tested four urban residential areas,three student dormitories,a rural household,a room was being decorated in Beijing from December 2016 to January 2018.The test contents include indoor PM1.0,PM2.5 and PM100 concentration,outdoor PM2.5 concentration and the temperature and humidity of indoor and outdoor.And use SPSS software to perform statistical analysis of test results.Based on indoor particulate matter PM1.0,PM2.5 and PM10 concentration level,relevance and influence factors analysis,different home indoor and outdoor PM2.5 mass concentration level measurement analysis and explore the influence of temperature and humidity of the indoor particle concentration.The main conclusions are as follows:?1?When measured indoor households have no indoor pollution sources,the indoor PM2.5concentration is always lower than outdoor.When measured indoor households have indoor pollution sources,the indoor household PM2.5 particulate emission intensity of urban households is ranked as follows:smoking>cooking>cleaning.The man-made sources of pollution in rural areas will affect the indoor environment.The PM2.5 particulate emission intensity of rural households is ranked as follows:coal-fired>burning firewood>smoking>cleaning>people activities.?2?During the test,the doors and windows of the residence were found to be closed.When the outdoor haze began and ended,the indoor PM2.5 concentration decreased as the indoor PM2.5concentration increased and there was a delay.The delay time is less than 10 minutes at the beginning of smog,and more than 1 hour at the end of haze.?3?The average mass concentration of PM2.5 in urban residential areas during the measurement period was lower than the national standard limit value of 0.075 mg/m3,and the average mass concentration of PM2.5 in rural household was higher than the standard limit of0.075 mg/m3.?4?The average ratio of indoor PM1.0/PM2.5 in the measured households ranged from 0.875to 0.969,indicating that the PM2.5 particulate matter in the measured residence was mainly PM1.0.?5?There is a correlation among PM1.0,PM2.5,and PM10 mass concentration in the residences.A linear regression analysis was performed on the PM1.0,PM2.5,and PM10 mass concentrations in the individual residences.PM1.0 and PM2.5 were present in all indoor residential particulates.The goodness of fit was above 90%,and the linear correlation between PM1.0 and PM2.5 was extremely strong.PM2.5 and PM10 also showed a strong correlation.After the F-test,the results showed statistically significant.?6?Examining the impact of indoor pollution sources,it was found that the smoking ratio of PM1.0/PM2.5 in the room exceeded 90%,and the smoking mainly produced fine particulate matter PM1.0.The PM2.5 decay rate of the same room opening window smoking particulate matter is approximately 9 times that of the closed window room.The effects of household cleaning activities,cooking,and labor activities specific to rural households on indoor particulate matter are mainly concentrated in the 2.5 to 10?m particle size segment.Opening the cooker hood during cooking is four times the rate of decay of particulate matter in rooms that do not turn on the hood.In the renovation of the room,coarse particles PM10 were produced,which had no effect on the PM2.5 concentration of the fine particles.?7?The trend of indoor and outdoor PM2.5 concentrations in residential houses without indoor pollution sources and in non-indoor pollution sources during the hazy days of urban housing are basically the same.By linear fitting and statistical analysis,the residence of indoor and outdoor PM2.5 concentrations showed a positive linear correlation between two environments.The Pearson correlation coefficient of non-indoor pollution sources in good weather was 0.81 or more,with statistical significance.When there is no indoor pollution source during haze days,the linear correlation of the indoor and outdoor PM2.5 concentration decreases as the outdoor haze increases.When there is indoor pollution source during haze days and good days,the indoor and outdoor PM2.5 concentration is not related to the wireless correlation.The concentration of indoor particulates is contributed by the indoor pollution sources and has nothing to do with the outdoor weather pollution levels.the rural households surveys were conducted in good weather.The outdoor pollution sources of measured rural household were mainly firewood for cooking,coal-fired heating,labor and other personnel activities.The outdoor pollution source had short duration and high transient concentration.The Spearman correlation coefficient of mass concentration PM2.5 between indoor and outdoor was greater than0.7.That reflects a strong positive correlation between measured indoor and outdoor PM2.5concentrations in rural households.?8?The Kruskal-Wallis H test and the Mann-Whitney U test were performed on the I/O ratios of different types of households.The results showed that the indoor/outdoor PM2.5concentration I/O ratios among different households were significantly different?P<0.01?.And the results have statistical significance.There was no significant difference between the haze weather and good weather I/O ratio when there was no indoor pollution source.?9?During the tested period in autumn,the measured household relative humidity was between 10%and 50%.The average concentration of particulate matter in the household increased with the increase of relative humidity.The ratio of PM1.0/PM2.5 remained basically unchanged,and the ratio of PM2.5/PM10 increased.During the winter heating period,the measured household relative humidity ranged from 50%to 80%.In this range,the average concentration of particulate matter decreased with the increase of relative humidity.The ratio of PM1.0/PM2.5 remained basically unchanged,and the ratio of PM2.5/PM10 decreased.?10?Spearman correlation analysis revealed that the indoor and outdoor temperature difference was significantly negatively correlated with indoor PM10 concentration?P<0.01?.The indoor and outdoor temperature difference was significantly negatively correlated with indoor PM2.5 concentration?P<0.05?.The indoor and outdoor temperature difference was Indoor PM1.0 concentration has no correlation.The greater particle size of the particles,the stronger negative correlation between the indoor and outdoor temperature differences.This paper has important implications for improving the environment of the residence and protecting human health.And provide a theoretical basis for the control of indoor particles. |
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