Higher health effects of ambient particles during the warm season: The role of infiltration factors

Investigation of source and infiltration of toxic metals in indoor PM2.5 using Pb isotopes during a season of high pollution in an urban area

Lead (Pb) isotope ratio has been applied in source investigation for particulate matter in size < 2.5 μm. However, arsenic (As) and cadmium (Cd) are carcinogenic to human and their isotope analysis is difficult. This study investigated whether the Pb isotope ratio was a useful indicator in identifying the sources of As and Cd indoors and investigating its influencing factors. This study also calculated the infiltration factor (Finf) for metals to assess the influences of indoor- and outdoor-generated metals to indoor air. The As and Cd concentrations in indoor air were 0.87 ± 0.69 and 0.19 ± 0.15 ng/m3, respectively; the corresponding values for outdoor air were 1.44 ± 0.80 and 0.33 ± 0.19 ng/m3. The Finf of As and Cd were 0.60 ± 0.37 and 0.58 ± 0.39, and outdoor was a predominant contributor to indoor As and Cd. The Pb isotopes ratio indicated that traffic-related emission was a major contributor to Pb. The Pb concentration was associated with those of As and Cd in indoor or outdoor air, as was the 208Pb/207Pb ratio in outdoor air. Significant correlations between indoor 208Pb/207Pb values and As and Cd concentrations in indoor air were found only in study houses with air change rate > 1.5 h-1. These findings suggested that traffic-related emission was identified as a major source of As and Cr. The 208Pb/207Pb is a useful indicator in investigating the source of As and Cd; however, the air change rate influences the applicability of this approach on source identification.

Association between ambient temperature and chronic rhinosinusitis

BACKGROUND

Chronic exposure to particulate matter air pollution (PM2.5 ) is associated with chronic rhinosinusitis (CRS). Elevated ambient temperature may increase PM2.5 levels and thereby exacerbate sinonasal symptoms. This study investigates the association between high ambient temperature and the risk of CRS diagnosis.

METHODS

Patients with CRS were diagnosed at Johns Hopkins hospitals from May to October 2013-2022, and controls were matched patients without CRS meanwhile. A total of 4752 patients (2376 cases and 2376 controls) were identified with a mean (SD) age of 51.8 (16.8) years. The effect of maximum ambient temperature on symptoms was estimated with a distributed lag nonlinear model (DLNM). Extreme heat was defined as 35.0°C (95th percentile of the maximum temperature distribution). Conditional logistic regression models estimated the association between extreme heat and the risk of CRS diagnosis.

RESULTS

Exposure to extreme heat was associated with increased odds of exacerbation of CRS symptoms (odds ratio [OR] 1.11, 95% confidence interval [CI] 1.03-1.19). The cumulative effect of extreme heat during 0-21 lag days was significant (OR 2.37, 95% CI 1.60-3.50) compared with the minimum morbidity temperature (MMT) at 25.3°C. Associations were more pronounced among young and middle-aged patients and patients with abnormal weight.

CONCLUSIONS

We found that short-term exposure to high ambient temperature is associated with increased CRS diagnosis, suggesting a cascading effect of meteorological phenomena. These results highlight climate change's potentially deleterious health effects on upper airway diseases, which could have a significant public health impact.

Causal effect of PM1 on morbidity of cause-specific respiratory diseases based on a negative control exposure

BACKGROUND

Extensive studies have linked PM_2.5 and PM₁₀ with respiratory diseases (RD). However, few is known about causal association between PM₁ and morbidity of RD. We aimed to assess the causal effects of PM₁ on cause-specific RD.

METHODS

Hospital admission data were obtained for RD during 2014 and 2019 in Beijing, China. Negative control exposure and extreme gradient boosting with SHapley Additive exPlanation was used to explore the causality and contribution between PM₁ and RD. Stratified analysis by gender, age, and season was conducted.

RESULTS

A total of 1,183,591 admissions for RD were recorded. Per interquartile range (28 μg/m³) uptick in concentration of PM₁ corresponded to a 3.08% [95% confidence interval (CI): 1.66%-4.52%] increment in morbidity of total RD. And that was 4.47% (95% CI: 2.46%-6.52%) and 0.15% (95% CI: 1.44%-1.78%), for COPD and asthma, respectively. Significantly positive causal associations were observed for PM₁ with total RD and COPD. Females and the elderly had higher effects on total RD, COPD, and asthma only in the warm months (Z = 3.03, P = 0.002; Z = 4.01, P < 0.001; Z = 3.92, P < 0.001; Z = 2.11, P = 0.035; Z = 2.44, P = 0.015). Contribution of PM₁ ranked first, second and second for total RD, COPD, and asthma among air pollutants.

CONCLUSION

PM₁ was causally associated with increased morbidity of total RD and COPD, but not causally associated with asthma. Females and the elderly were more vulnerable to PM₁-associated effects on RD.

Experimental and numerical analysis of indoor air quality affected by outdoor air particulate levels (PM1.0, PM2.5 and PM10), room infiltration rate, and occupants' behaviour

This study conducted an experimental analysis of how indoor air quality (IAQ) is influenced by the outdoor air pollutants levels, infiltration rate, and occupants' behaviours. The impacts of these factors on IAQ were analyzed using on-site measurements and numerical simulations. The results contribute to a better understanding of how to control the Indoor Particulate Level (IPL) for the specific conditions of the studied building. Results showed that occupant behaviour was the primary factor in determining the IPL, significantly changing the number of outdoor particles introduced to the building. Moreover, it was found that the IPL was exponentially correlated to the Outdoor Particulate Level (OPL). Based on numerical simulations, this study concluded that smaller particles do not always have more chance than larger particles of accessing the indoor environment through the building envelope. Meanwhile, a steady-state indoor particle concentration numerical model was established and verified using the 4-fold cross-validation method. Finally, simulation results identified that the room infiltration rate had a positive linear impact on IAQ if the OPL was under 30 μg/m³. This is because the increased air exchange rate can help to dilute indoor air pollutants when the outdoor air is relatively clean.

Impacts of Regional Speed Control Strategy Based on Macroscopic Fundamental Diagram on Energy Consumption and Traffic Emissions: A Case Study of Beijing

Numerous studies shown that particulate matter in the ambient environment has a significant impact on the health of the respiratory system. To understand the interrelationships between urban built environment, transportation operations and health, this study proposes an innovative approach that uses real-world GPS datasets to calculate energy consumption and emissions from transportation. The experiment used the traffic operation state in the Fourth Ring Road of Beijing as the research object and tested the impact of using the Regional speed optimization (RSO) strategy based on Macroscopic Fundamental Diagram (MFD) on energy consumption and emissions during peak hours. The impact of traffic emission on the health of roadside pedestrians is also considered. Changes in PM2.5 concentrations around four different built-up areas were calculated and compared. The computational experiments indicate that the PM2.5 pollutants exhausted by the traffic on the Ring Road during peak hours can reach up to 250 μg/m3, while the traffic emission on general roads near residential areas is only 50 μg/m3. Adopting Regional speed optimization can reduce the energy consumption of the road network by up to 18.8%. For roadside runners, the PM2.5 inhalation caused by night running in commercial and recreational areas is about 1.3-2.6 times that of night running in residential areas. Compared with morning or night running, the risk of respiratory disease caused by PM2.5 inhalation was about 10.3% higher than commuter running behavior. The research results provide a useful reference for energy conservation and emission reduction control strategies for different road types in cities and help existing cities to establish a traveler health evaluation system caused by traffic operation.

Outdoor and indoor fine particulate matter at skilled nursing facilities in the western United States during wildfire and non-wildfire seasons

Wildfire activity is increasing in parts of the world where extreme drought and warming temperatures contribute to fireprone conditions, including the western United States. The elderly are among the most vulnerable, and those in long-term care with preexisting conditions have added risk for adverse health outcomes from wildfire smoke exposure. In this study, we report continuous co-located indoor and outdoor fine particulate matter (PM_2.5 ) measurements at four skilled nursing facilities in the western United States. Throughout the year 2020, over 8000 h of data were collected, which amounted to approximately 300 days of indoor and outdoor sampling at each facility. The highest indoor 24 h average PM_2.5 recorded at each facility was 43.6 µg/m³ , 103.2 µg/m³ , 35.4 µg/m³ , and 202.5 µg/m³ , and these peaks occurred during the wildfire season. The indoor-to-outdoor PM_2.5 ratio and calculated infiltration efficiencies indicated high variation in the impact of wildfire events on Indoor Air Quality between the four facilities. Notably, infiltration efficiency ranged from 0.22 to 0.76 across the four facilities. We propose that this variability is evidence that PM_2.5 infiltration may be impacted by modifiable building characteristics and human behavioral factors, and this should be addressed in future studies.

Estimations of infiltration factors of diurnal PM2.5 and heavy metals in children's bedrooms

Children are the sensitive population to fine particulate matter (PM_2.5 ) exposure and spend most of their time in bedroom. Infiltration factor (F_inf ) can be used to calculate the fraction of total indoor PM_2.5 with outdoor origin to increase the accuracy of exposure assessment. However, studies have ignored the diurnal variations of PM_2.5 F_inf values, and a few studies have estimated F_inf values for heavy metals in PM_2.5 in children's bedrooms. To calculate the PM_2.5 F_inf , real-time indoor and outdoor PM_2.5 concentrations and occupants' activities were collected in 56 study bedrooms. At 22 of the 56 study bedrooms, PM_2.5 samples were also collected for heavy metals analysis. We noted the PM_2.5 F_inf was higher during the daytime (0.70 ± 0.23) than nighttime (0.54 ± 0.27) during the hot season, and the time of air conditioner use was longer at nighttime. The largest F_inf value of heavy metal was V (0.88 ± 0.25), followed by Pb (0.85 ± 0.28), Mn (0.72 ± 0.26), Cr (0.69 ± 0.35), and Zn (0.61 ± 0.32), with a larger variation. Our findings suggest that the estimations of diurnal PM_2.5 and heavy metals F_inf values are necessary to increase the accuracy of exposure assessment.

Comparative Modelling Analysis of Air Pollutants, PM2.5 and Energy Efficiency Using Three Ventilation Strategies in a High-Rise Building: A Case Study in Suzhou, China

This study investigated the ventilation efficiency and energy performance of three ventilation strategies—an all-air system (AAS), a radiant panel system with a displacement ventilation system (DPS), and a radiant panel system with a decentralized ventilation system (DVS). The research analyzed the indoor air quality (IAQ) in a high-rise building based on the building’s height, the air handling unit (AHU) location, air infiltration rate, outdoor air pollution rate, seasonal change, and air filter efficiency. The results indicated that the AAS had the best performance in terms of IAQ in the high-rise building in winter; however, the AAS also had the highest annual energy demand. For the same conditions, the DVS consumed less energy but had the worst performance in maintaining a satisfactory IAQ. Considering energy consumption, it is worth developing the DVS further to improve ventilation performance. By applying a double-filter system on the lower floors in a high-rise building, the DVS’s ventilation performance was dramatically improved while at the same time consuming less energy than the original DPS and AAS. The application of DVS can also minimize the negative effect of the infiltration rate on indoor air quality (IAQ) in a building, which means that the DVS can better maintain IAQ within a healthy range for a more extended period. Moreover, it was found that the DVS still had a substantial potential for saving energy during the season when the outdoor air was relatively clean. Hence, it is highly recommended that the DVS is used in high-rise buildings.

Associations between PM1 exposure and daily emergency department visits in 19 hospitals, Beijing

Although the adverse health effects caused by PM_2.5 (particulate matter (PM) with an aerodynamic diameter <2.5 μm) and PM₁₀ (PM with an aerodynamic diameter <10 μm) have been examined in numeric studies, far less scientific evidence is available for PM with an aerodynamic diameter <1 μm (PM₁). We performed a time series analysis to elucidate the associations between PM₁ exposure and emergency department visits (EDVs) in 19 hospitals within Beijing. During the study period from January 2016 to December 2017, the average PM₁ (mean ± standard deviation) was determined to be 39 ± 39 μg/m³, which was approximately 36% lower than that of 61 ± 56 μg/m³ for PM_2.5. Results based on meta-analysis suggest that non-accidental and respiratory EDVs increased by 0.47% (95% confidence interval, CI: 0.35, 0.59%) and 0.59% (95%CI: 0.38, 0.8%) per 10 μg/m³ uptick in PM₁ exposure. By comparison, the magnitude downgraded to 0.27% (95%CI: 0.15, 0.39%) in non-accidental and 0.32% (95%CI: 0.18, 0.47%) in respiratory EDVs for PM_2.5 exposure, indicating that PMs of a smaller size may be a higher risk factor for EDVs. No significant differences in PM-associated EDV effects were noted between males and females, while stratified analysis by age and season illustrated that stronger effects were found for a warm season and young population. Our analysis reinforces the notion that PM₁ exhibited a higher risk for EDVs, suggesting more efforts may be required to mitigate PM₁ pollution.

Impacts of implementing Healthy Building guidelines for daily PM2.5 limit on premature deaths and economic losses in urban China: A population-based modeling study

Given a large fraction of people's exposure to urban PM_2.5 occur indoors, reducing indoor PM_2.5 levels may offer a more feasible and immediate way to save substantial lives and economic losses attributable to PM_2.5 exposure. We aimed to estimate the premature mortality and economic loss reductions associated with achieving the newly established Chinese indoor air guideline and a few hypothetical indoor PM_2.5 guideline values. We used outdoor PM_2.5 concentrations from 1497 monitoring sites in 339 Chinese cities in 2015, coupled with a steady-state mass balance model, to estimate indoor concentrations of outdoor-infiltrated PM_2.5. Using province-specific time-activity patterns for urban residents, we estimated outdoor and indoor exposures to PM_2.5 of outdoor origin. We then proceeded to use localized census-based concentration-response models and the value of statistical life estimates to calculate premature deaths and economic losses attributable to PM_2.5 exposure across urban China. Finally, we estimated potentially avoidable mortality and corresponding economic losses by meeting the current 24-hour based guideline and various hypothetical indoor limits for PM_2.5. In 2015 in urban areas of mainland China, the city-specific annual mean outdoor and indoor PM_2.5 concentrations ranged 9-108 μg/m³ and 5-56 μg/m³, respectively. Indoor exposures contributed 62%-91% daily and 68%-83% annually to the total time-weighted exposures. The potential reductions in total deaths and economic losses for the scenario in which daily indoor concentrations met the current guideline of 75 μg/m³, 37.5 μg/m³, and 25 μg/m³ were 16.9 (95% CI: 0.7-62.1) thousand, 87.7 (95% CI: 9.7-197.7) thousand, and 165.5 (95% CI: 30.8-304.0) thousand, respectively. The corresponding reductions in economic losses were 5.7 (95% CI: 0.2-34.8) billion, 29.4 (95% CI: 2.4-109.6) billion, and 55.2 (95% CI: 7.7-168.0) billion US Dollars, respectively. Deaths and economic losses would be reduced exponentially within the range of 0-75 μg/m³ for hypothetical indoor PM_2.5 limits. The findings demonstrate the effectiveness of reducing indoor concentrations of outdoor-originated PM_2.5 in saving substantial lives and economic losses in China. The analysis provides quantitative evidence to support the implementation of an indoor air quality guideline or standard for PM_2.5.

Outdoor-to-indoor transport of ultrafine particles: Measurement and model development of infiltration factor

Ambient ultrafine particles (UFPs: particles of diameter less than 100 nm) cause significant adverse health effects. As people spend most time indoors, the outdoor-to-indoor transport of UFPs plays a critical role in the accuracy of personal exposure assessments. Herein, a strategy was proposed to measure and analyze the infiltration factor (F_inf) of UFPs, an important parameter quantifying the fraction of ambient air pollutants that travel inside and remain suspended indoors. Ninety-three measurements were conducted in 11 residential rooms in all seasons in Beijing, China, to investigate F_inf of UFPs and its associated influencing factors. A multilevel regression model incorporating eight possible factors that influence infiltration was developed to predict F_inf and F_infSOA (defined as the ratio of indoor to outdoor UFP concentrations without indoor sources, but with indoor secondary organic aerosol (SOA) formation). It was found that the air change rate was the most important factor and coagulation was considerable, while the influence of SOA formation was much smaller than that of other factors. Our regression model accurately predicted daily-average F_inf. The annually-averaged F_inf of UFPs was 0.66 ± 0.10, which is higher than that of PM_2.5 and PM₁₀, demonstrating the importance of controlling indoor UFPs of outdoor origin.

Integrated Evaluation of Indoor Particulate Exposure: The VIEPI Project

Despite the progress made in recent years, reliable modeling of indoor air quality is still far from being obtained. This requires better chemical characterization of the pollutants and airflow physics included in forecasting tools, for which field observations conducted simultaneously indoors and outdoors are essential. The project “Integrated Evaluation of Indoor Particulate Exposure” (VIEPI) aimed at evaluating indoor air quality and exposure to particulate matter (PM) of humans in workplaces. VIEPI ran from February 2016 to December 2019 and included both numerical simulations and field campaigns carried out in universities and research environments located in urban and non-urban sites in the metropolitan area of Rome (Italy). VIEPI focused on the role played by micrometeorology and indoor airflow characteristics in determining indoor PM concentration. Short- and long-term study periods captured diurnal, weekly, and seasonal variability of airflow and PM concentration. Chemical characterization of PM10, including the determination of elements, ions, elemental carbon, organic carbon, and bioaerosol, was also carried out. Large differences in the composition of PM10 were detected between inside and outside as well as between different periods of the day and year. Indoor PM composition was related to the presence of people, to the season, and to the ventilation regime.

Personal exposure to ambient PM2.5, PM10, O3, NO2, and SO2 for different populations in 31 Chinese provinces

Most epidemiological studies usually employ ambient air pollutant concentrations as a proxy of personal exposure to air pollutants originating outdoors, which could lead to a biased estimation of health effects. Herein, we modeled infiltration and exposure factors as the modifications of personal exposure to ambient PM_2.5, PM₁₀, O₃, NO₂, and SO₂ for all seasons, genders, and ages in 31 Chinese provinces. The annual average exposure factors of PM₁₀, PM_2.5, O₃, NO₂, and SO₂ were 0.42 ± 0.13 (arithmetic mean ± standard deviation), 0.68 ± 0.14, 0.34 ± 0.12, 0.50 ± 0.14, and 0.40 ± 0.13, respectively. We observed significant age, gender, seasonal, and geographical differences in infiltration and exposure factors for all studied ambient air pollutants. These factors were higher in southern China than in the north, and they were the highest in summer and the lowest in winter. The exposure factor of minors (age < 18 years) was significantly lower than that of adults (age ≥ 18 years, P < 0.01). Adult males had higher exposure factors than females (P < 0.01). Epidemiological studies utilizing outdoor concentrations of air pollutants could overestimate personal exposure to these pollutants. The present study could help in reducing the bias in the estimation of the health effects of air pollutants.

Determinants of personal exposure to fine particulate matter in the retired adults - Results of a panel study in two megacities, China

This study aimed to investigate the relationship between outdoor, indoor, and personal PM_2.5 exposure in the retired adults and explore the effects of potential determinants in two Chinese megacities. A longitudinal panel study was conducted in Nanjing (NJ) and Beijing (BJ), China, and thirty-three retired non-smoking adults aged 43-86 years were recruited in each city. Repeated measurements of outdoor-indoor-personal PM_2.5 concentrations were measured for five consecutive 24-h periods during both heating and non-heating seasons using real-time and gravimetric methods. Time-activity and household characteristics were recorded. Mixed-effects models were applied to analyze the determinants of personal PM_2.5 exposure. In total, 558 complete sets of collocated 24-h outdoor-indoor-personal PM_2.5 concentrations were collected. The median 24-h personal PM_2.5 exposure concentrations ranged from 43 to 79 μg/m³ across cities and seasons, which were significantly greater than their corresponding indoor levels (ranging from 36 to 68 μg/m³, p < 0.001), but significantly lower than outdoor levels (ranging from 43 to 95 μg/m³, p < 0.001). Indoor and outdoor PM_2.5 concentrations were the strongest determinants of personal exposures in both cities and seasons, with R_M² ranging from 0.814 to 0.915 for indoor and from 0.698 to 0.844 for outdoor PM_2.5 concentrations, respectively. The personal-outdoor regression slopes varied widely among seasons, with a pronounced effect in BJ (NHS: 0.618 ± 0.042; HS: 0.834 ± 0.023). Ventilation status, indoor PM_2.5 sources, personal characteristics, and meteorological factors, were also found to influence personal exposure levels. The city and season-specific models developed here are able to account for 89%-93% of the variance in personal PM_2.5 exposure. A LOOCV analysis showed an R² (RMSE) of 0.80-0.90 (0.21-0.36), while a 10-fold CV analysis demonstrated a R² (RMSE) of 0.83-0.90 (0.20-0.35). By incorporating potentially significant determinants of personal exposure, this modeling approach can improve the accuracy of personal PM_2.5 exposure assessment in epidemiologic studies.

Seasonal Variation in the Biological Effects of PM2.5 from Greater Cairo

Greater Cairo (Egypt) is a megalopolis where the studies of the air pollution events are of extremely high relevance, for the geographical-climatological aspects, the anthropogenic emissions and the health impact. While preliminary studies on the particulate matter (PM) chemical composition in Greater Cairo have been performed, no data are yet available on the PM’s toxicity. In this work, the in vitro toxicity of the fine PM (PM_2.5) sampled in an urban area of Greater Cairo during 2017–2018 was studied. The PM_2.5 samples collected during spring, summer, autumn and winter were preliminary characterized to determine the concentrations of ionic species, elements and organic PM (Polycyclic Aromatic Hydrocarbons, PAHs). After particle extraction from filters, the cytotoxic and pro-inflammatory effects were evaluated in human lung A549 cells. The results showed that particles collected during the colder seasons mainly induced the xenobiotic metabolizing system and the consequent antioxidant and pro-inflammatory cytokine release responses. Biological events positively correlated to PAHs and metals representative of a combustion-derived pollution. PM_2.5 from the warmer seasons displayed a direct effect on cell cycle progression, suggesting possible genotoxic effects. In conclusion, a correlation between the biological effects and PM_2.5 physico-chemical properties in the area of study might be useful for planning future strategies aiming to improve air quality and lower health hazards.