The effect of coarse ambient particulate matter on first, second, and overall hospital admissions for respiratory disease among the elderly

The objective of this article is to examine differences in the effect of ambient particulate matter on first, second, and overall hospital admissions for respiratory disease among the elderly. We studied 8989 adults 65 yr of age or older living in the greater Vancouver area who were admitted to hospital for any acute respiratory disease (ICD-9 codes 460-519) between June 1, 1995, and March 31, 1999. Time-series analysis was used to evaluate the association between respiratory admissions and daily measures of particulate matter (PM10, PM2.5, and PM10 - 2.5) in urban air, after adjustment for gaseous copollutants (CO, O3, NO2, and SO2) and meteorological variables. Repeated admissions for respiratory disease were common among the elderly. Approximately 30% of the subjects were readmitted to hospital after the first admission; 9% had more than 2 admissions for respiratory disease during the 4-yr study period. PM10 - 2.5 was significantly associated with the second and overall admissions for respiratory disease, but not with the first admission. The adjusted relative risks for an increment of 4.2 microg/m(3) in -day average PM10 - 2.5 concentrations were 1.03 (95% confidence interval: 0.98-1.09) for the first admission, 1.22 (1.10-1.36) for the second admission, and 1.06 (1.02, 1.11) for overall admissions. There was no significant association between PM2.5 and hospital admissions for respiratory disease among the elderly. Our data suggest that (1) people with a history of respiratory admissions are at a higher risk of respiratory disease in relation to particulate air pollution in urban areas, (2) analyses based on overall rather than repeated hospital admissions lead to lower estimates of the risk of respiratory disease associated with particulate air pollution, and (3) PM10 - 2.5 has a larger effect on respiratory admissions than PM2.5.     

Association between Air Pollution and Multiple Respiratory Hospitalizations among the Elderly in Vancouver,Canada

Recurrent events, such as repeated hospital admissions for the same health outcome, occur frequently in environmental health studies. In this study, we conducted an analysis of data on repeated respiratory hospitalizations among the elderly in Vancouver, Canada, for the period of June 1, 1995, to March 31, 1999, using a new method proposed by () for recurrent events, and compared it with some traditional methods. In particular, we assessed the impact of ambient gaseous (SO₂, NO₂, CO, and O₃) and particulate pollutants (PM₁₀, PM_2.5, and PM_10–2.5) as well as the coefficient of haze (CoH) on recurrent respiratory hospital admissions. Using the new procedure, significant associations were found between admissions and 3-day, 5-day, and 7-day moving averages of the ambient SO₂ concentrations, with the strongest association observed at the 7-day lag (RR = 1.044, 95% CI: 1.018–1.070). We also found PM_10–2.5 for 3-day and 5-day lag to be significant, with the strongest association at 5-day lag (RR = 1.020, 95% CI: 1.001–1.039). No significant associations with admission were found with current day exposure.     

Effects of ambient air pollution exposure on frequency of hospital admissions for appendicitis in Taipei,Taiwan

The relationship between exposure to ambient air pollutants and hospital admissions for appendicitis is not known. This study examined whether an association existed between air contaminant levels and frequency of hospital admissions for appendicitis in Taipei, Taiwan. Ambient air pollution and hospital admission data for Taipei were obtained for 2009–2013. Relative risk (RR) of hospital admissions was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. In the single pollutant model, on warm days (> 23°C), number of appendicitis admissions was significantly associated with particulate matter (PM_2.5), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃). On cool days (< 23°C), a significant rise in number of admissions for appendicitis was related to PM₁₀, NO₂, and O₃ concentrations. In the two-pollutant models, on warm days, NO₂ and O₃ were significantly associated with increased number of admissions for appendicitis when combined with each of the other pollutants. On cool days, NO₂, O₃, and PM₁₀ remained significant for higher appendicitis admission cases in all two-pollutant models. In conclusion, higher levels of ambient air pollutants may be associated with increase in the risk of hospital admissions for appendicitis in Taipei.     

Influence of Relatively Low Level of Particulate Air Pollution on Hospitalization for COPD in Elderly People

To assess the association between relatively low levels of size-fractioned particulate matter (PM) and hospitalization for chronic obstructive pulmonary disease (COPD), we conducted a time-series analysis among elderly people 65 yr of age or more living in Vancouver between June 1995 and March 1999. Measures of thoracic PM (PM₁₀), fine PM (PM_2.5), coarse PM (PM_10?2.5), and coefficient of haze (COH) were examined over periods varying from 1 to 7 days prior to hospital admissions. Generalized additive models (GAMs; general linear models, GLMs) were used, and temporal trends and seasonal and subseasonal cycles in COPD hospitalizations were removed by using GLM with parametric natural cubic splines. The relative risks were calculated based on an incremental exposure corresponding to the interquartile range of these measures, and were adjusted for daily weather conditions and gaseous pollutants. PM measures had a positive effect on COPD hospitalization, especially 0 to 2 days prior to the admissions, before copollutants were accounted for. For 3-day average levels of exposure the relative risk estimates were 1.13 (95% confidence interval: 1.05–1.21) for PM₁₀, 1.08 (1.02–1.15) for PM_2.5, 1.09 (1.03–1.16) for PM_10?2.5, and 1.05 (1.01–1.09) for COH. The associations were no longer significant when NO₂ was included in the models. We concluded that the particle-related measures were significantly associated with COPD hospitalization in the Vancouver area, where the level of air pollution is relatively low, but the effects were not independent of other air pollutants.     

Assessments of population exposure to environmental pollutants using air quality measurements during Commonwealth Games-2010

Abstract

During the “Commonwealth Games” 2010 (CWG-2010) in Delhi, the Indian government has implemented an ambitious project “System of Air quality Forecasting And Research (SAFAR)” for monitoring and forecasting air-quality scenario. Using high-precision spatio-temporal measurements of criteria pollutants from the SAFAR network, the number of cases are estimated for total, cardiovascular and respiratory mortalities and hospital admissions. In a thinly populated airport area, the excess number of cases for total mortality show ～10 for PM_2.5 and 25 for PM₁₀, whereas, ～110 for PM_2.5 and ～300 for PM₁₀ in most populous Delhi University (DU) area. Cardiovascular mortality in airport area show ～5 and <10 for PM_2.5 and PM₁₀, respectively, but, in DU area show ～55 for PM_2.5 and ～140 for PM₁₀. In DU locality, respiratory mortality shows ～7 and ～20 for PM_2.5 and PM₁₀ and, hospital admissions show ～11 and ～30 for PM_2.5 and PM₁₀, respectively. In airport area, excess cases of respiratory mortality and hospital admission tends to one for exposure to PM_2.5 or PM₁₀ levels indicating effective exposure is the key factor for health hazards. As public health gains, low air pollution levels were observed before the CWG due to effective washout by monsoonal rain and during CWG under policy-induced air quality measures could increase the life expectancy as against to post-CWG period. These results are important for the megacities in developing world as the SAFAR project is internationally recognized by the Global Urban Research Meteorology and Environment of the World Meteorological Organization.     

Fine particulate air pollution associated with increased risk of hospital admissions for hypertension in a tropical city,Kaohsiung, Taiwan

The aim of this study was to assess whether a correlation exists between fine particles (PM_2.5) levels and number of hospital admissions for hypertension in Kaohsiung, Taiwan. Hospital admission frequency and ambient air pollution data were obtained for Kaohsiung for 2009–2013. A time-stratified case-crossover method was used to estimate relative risk for hospital admissions, controlling for weather, day of the week, seasonality, and long-term time trends. Odds ratios and 95% confidence intervals were calculated for a 10 µg/m³ increment of PM_2.5 for lags from days 0 to 6. Data showed no significant associations between PM_2.5 levels and number of hypertension-related hospital admissions on warm days (>25°C). However, on cool days (<25°C), a significant positive association was found with frequency of hypertension admissions in the single-pollutant model (without adjusting for other pollutants) with a 10 µg/m³ rise in PM_2.5 on day of admission (lag 0) associated with a 12% increase in number of admissions for hypertension. In the two-pollutant model, the association of PM_2.5 with rate of hypertension hospitalizations remained significant after including SO₂ or O₃ on lag day 0. Data demonstrate that an association between short-term exposure to PM_2.5 and elevated risk of hypertension-related hospital admissions may exist in Kaohsiung, Taiwan, a tropical city.     

An Analysis of the Association Between Respiratory Symptoms in Subjects with Asthma and Daily Air Pollution in Spokane,Washington

The association between respiratory symptoms and ambient levels of particulate matter (PM) air pollution has been the focus of several panel studies. The majority of studies focused only on PM₁₀, were conducted for relatively short periods, reported peak flow data, and involved children with asthma. The goal of our study was to evaluate the effect of particulate matter of various size fractions (PM₁₀, PM_2.5, PM_1.0, and PM coarse fraction) on respiratory symptoms in both adults and children with asthma monitored over many months. Daily diary data on respiratory symptoms and medication use were collected. Air pollution data were collected by the local air agency and Washington State University. Data were collected in Spokane, WA, a semiarid city with diverse sources of particulate matter, including motor vehicles, woodstoves, agricultural burning, resuspended road dust, and dust storms. Sixteen adults and nine children living in Spokane participated in the study. The majority of adult subjects participated for over 1 yr and the children were studied for over 8 mo. In the children, we found a strong association between cough and PM₁₀, PM_2.5, PM coarse fraction, and PM_1.0 (p <. 05). Sputum production and runny nose were associated with PM₁₀ and coarse fraction. However, no association was found between the presence of any respiratory symptom any PM metric in the adult subjects. These positive associations between various metrics of PM and respiratory symptoms in children suggest that children are more sensitive than adults to the effects of increased levels of PM air pollution or that the central site monitor was more representative for children who spend more time outdoors than adults. These findings also suggest that both larger and smaller particles can aggravate asthma symptoms.     

Heterogeneities in Inflammatory and Cytotoxic Responses of RAW 264.7 Macrophage Cell Line to Urban Air Coarse,Fine, and Ultrafine Particles From Six European Sampling Campaigns

We investigated the cytotoxic and inflammatory activities of size-segregated particulate samples (particulate matter, PM) from contrasting air pollution situations in Europe. Coarse (PM_10?2.5), fine (PM_2.5?0.2), and ultrafine (PM_0.2) particulate samples were collected with a modified Harvard high-volume cascade impactor (HVCI). Mouse RAW 264.7 macrophages were exposed to the samples for 24 h. Selected inflammatory mediators, nitric oxide (NO) and cytokines (tumor necrosis factor alpha [TNFα], interleukin 6 [IL-6], macrophage inflammatory protein-2 [MIP-2]), were measured together with cytotoxicity (MTT test), and analysis of apoptosis and cell cycle (propidium iodide staining). The PM_10?2.5 samples had a much higher inflammatory activity than the PM_2.5?0.2 and PM_0.2 samples, but the PM_2.5?0.2 samples showed the largest differences in inflammatory activity, and the PM_0.2 samples in cytotoxicity, between the sampling campaigns. The PM_2.5?0.2 samples from traffic environments in springtime Barcelona and summertime Athens had the highest inflammatory activities, which may be related to the high photochemical activity in the atmosphere during the sampling campaigns. The PM_0.2 sample from wintertime Prague with proven impacts from local coal and biomass combustion had very high cytotoxic and apoptotic activities and caused a distinct cell cycle arrest. Thus, particulate size, sources, and atmospheric transformation processes affect the toxicity profile of urban air particulate matter. These factors may explain some of the heterogeneity observed in particulate exposure-response relationships of human health effects in epidemiological studies.     

Dose and Time Dependency of Inflammatory Responses in the Mouse Lung to Urban Air Coarse,Fine, and Ultrafine Particles From Six European Cities

We investigated the dose and time dependency of inflammatory and cytotoxic responses to size-segregated urban air particulate samples in the mouse lung. Coarse (PM_10?2.5), fine (PM_2.5?0.2), and ultrafine (PM_0.2) particles were collected in six European cities (Duisburg, Prague, Amsterdam, Helsinki, Barcelona, Athens) in selected seasons using a modified Harvard high-volume cascade impactor. Healthy C57Bl/6J mice were intratracheally exposed to the particulate samples in a 24-h dose-response study (1, 3, and 10 mg/kg) and in 4-, 12-, and 24-h time course studies (10 mg/kg). After the exposures, the lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: total cell number, cell differential, total protein, and lactate dehydrogenase (LDH) and cytokine (tumor necrosis alpha [TNF-α], interleukin-6 [IL-6], and keratinocyte-derived chemokine [KC]) concentrations. In general, PM_10?2.5 samples had higher inflammatory activity than PM_2.5?0.2 samples. PM_0.2 samples showed negligible inflammatory activity. PM_10?2.5 and PM_2.5?0.2 samples caused large increases in BALF cytokine concentrations at 4 h, but not at 12 or 24 h, after exposure. The BALF total cell number and total protein concentrations increased significantly at 12 h for both the PM_10?2.5 and PM_2.5?0.2 samples, but only PM_10?2.5 samples produced consistent, significant increases at 24 h after exposure. There was more heterogeneity in BALF cytokine and neutrophil cell number responses to PM_2.5?0.2 samples than to PM_10?2.5 samples between the sampling campaigns. Thus, particle size, sources, and atmospheric transformation processes affect the inflammatory activity and response duration of urban air particulate matter in the mouse lung.     

Short-term effects of fine particulate air pollution on hospital admissions for hypertension: A time-stratified case-crossover study in Taipei

This study was undertaken to determine whether there was a correlation between fine particle (PM_2.5) levels and hospital admissions for hypertension in Taipei, Taiwan. Hospital admissions for hypertension and ambient air pollution data for Taipei were obtained for the period from 2009 to 2013. The relative risk of hospital admissions was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. For the single pollutant model (without adjustment for other pollutants), the risk of hospital admissions for hypertension was estimated to increase by 12% on warm days (>23°C) and 2% on cool days (<23°C), respectively. There was no indication of an association between levels of PM_2.5 and risk of hospital admissions for hypertension. In two-pollutant model, PM_2.5 remained nonsignificant after inclusion of any of the other air pollutants (SO₂, NO₂, CO, or O₃) both on warm and cool days, but a numerically greater response was seen on warm days. Data thus indicate that in Taipei, hospital admissions for hypertension occur as a consequence of factors not related to ambient air exposure.     

Fine particulate air pollution and hospital admissions for congestive heart failure: a case-crossover study in Taipei

Abstract

This study was undertaken to determine whether there was an association between fine particles (PM_2.5) levels and hospital admissions for congestive heart failure (CHF) in Taipei, Taiwan. Hospital admissions for CHF and ambient air pollution data for Taipei were obtained for the period 2006–2010. The relative risk of hospital admissions was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality and long-term time trends. For the single pollutant model (without adjustment for other pollutants), increased CHF admissions were significantly associated with PM_2.5 both on warm days (>23?°C) and cool days (<23?°C), with an interquartile range increase associated with a 13% (95% CI?=?9–17%) and 3% (95% CI?=?0–7%) increase in CHF admissions, respectively. In the two-pollutant models, PM_2.5 remained significant after the inclusion of SO₂ or O₃ both on warm and cool days. This study provides evidence that higher levels of PM_2.5 increase the risk of hospital admissions for CHF.     

Association between ozone air pollution levels and hospitalizations for depression in Taipei: a time-stratified case-crossover study

ABSTRACT

Epidemiologic studies reported an association between exposure to ambient air pollutants and increased mortality rate attributed to suicide and suicide attempts. The investigation sought to determine whether there is an association between short-term ambient ozone (O₃) level exposure and daily hospital admissions for depression in Taipei from 2009 to 2013 using a time-stratified case-crossover design. In our single-pollutant model (with no adjustment for other pollutants), the % increase in daily hospital admissions for depression was 12% on warm days and 30% on cool days, per interquartile range (IQR) rise in O₃ levels, respectively. Ozone levels were significantly correlated with daily number of depression admissions both on warm and cool days. In our two-pollutant models, O₃ levels remained significant after adjusting for other air pollutants, including particulate matter (PM₁₀, PM_2.5), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and carbon monoxide (CO) both on warm and cool days. Although O₃ levels tended to be higher on warm days, admissions for depression were higher on cool days, suggesting that the relationship between O₃ concentrations and depression may be affected by temperature. Further study is needed to better understand these findings.     

Air pollution and hospital admissions for pneumonia: Are there potentially sensitive groups?

Recent studies have shown that air pollution is a risk factor for hospitalization for pneumonia. However, there is limited evidence to suggest what subpopulations are at greater risk from air pollution. This study was undertaken to examine the modifying effect of specific secondary diagnosis (including hypertension, diabetes, asthma, and upper respiratory infections) on the relationship between hospital admissions for pneumonia and ambient air pollutants. Hospital admissions for pneumonia and ambient air pollution data for Kaohsiung were obtained for the period 1996–2006. The relative risk of hospital admission was estimated using a case-crossover approach. We found that an interquartile range (IQR) increase in PM₁₀, NO₂, and CO on warm days was associated with a 28% (95% confidence interval [CI], 11–48%), 40% (95% CI, 20–63%), and 31% (95% CI, 19–45%), respectively, increase in admissions for pneumonia with upper respiratory infections (URI), but only 23% (95% CI, 18–28%), 30% (95% CI, 25–36%), and 24% (95% CI, 21–28%), respectively, increase for persons without URI. An IQR increase in PM₁₀, SO₂, and CO on cool days was associated with a 70% (95% CI, 50–92%), 30% (95% CI, 15–47%), and 64% (95% CI, 47–83%), respectively, increase in admissions in persons with URI, and an increase of 64% (95% CI, 57–70%), 18% (95% CI, 14–22%), and 55% (95% CI, 50–60%), respectively, in admissions in persons without URI. Our findings provide evidence that patients with comorbid URI may increase the risk of hospital admissions for pneumonia, in relation to air pollutant levels.     

Respiratory symptoms,lung function decrement and chronic obstructive pulmonary disease in pre-menopausal Indian women exposed to biomass smoke

Abstract

Background: The impact of chronic exposure to smoke from biomass burning on respiratory health has been examined.

Methods: Six-hundred and eighty-one non-smoking women (median age 35 years) from eastern India who cook exclusively with biomass (wood, dung and crop residues) and 438 age-matched women from similar neighborhood who cook with liquefied petroleum gas (LPG) were examined. Pulmonary function test was done by spirometry. The concentrations of particulate matter having diameter of < 10?µm (PM₁₀) and < 2.5?µm (PM_2.5) in indoor air was measured by real-time aerosol monitor.

Results: Compared with LPG users, biomass users had greater prevalence of upper (50.9 versus 28.5%) and lower respiratory symptoms (71.8 versus 30.8%) and dyspnea (58.4 versus 19.9%). They showed reduction in all parameters measured by spirometer especially in mid-expiratory volume. PM₁₀ and PM_2.5 concentration in biomass using kitchen were 2–3-times more than LPG-using kitchen, and the decline in spirometry values was positively associated PM₁₀ and PM_2.5 levels in indoor air after controlling education, family income and kitchen location as potential confounders. Overall, 29.7% of biomass users and 16.4% of LPG users had deficient lung function, and restrictive type of deficiency was predominant. Chronic obstructive pulmonary disease (COPD) was diagnosed in 4.6% of biomass and 0.9% of LPG users. Women who predominantly used dung cake and did not possess separate kitchen had poorer lung function.

Conclusion: Cumulative exposure to biomass smoke causes lung function decrement and facilitates COPD development even in non-smoking and relatively young pre-menopausal women.     

Chemical Compositions Responsible for Inflammation and Tissue Damage in the Mouse Lung by Coarse and Fine Particulate Samples from Contrasting Air Pollution in Europe

Inflammation is regarded as an important mechanism in mortality and morbidity associated with exposures of cardiorespiratory patients to urban air particulate matter. We investigated the association of the chemical composition and sources of urban air fine (PM_2.5?0.2) and coarse (PM_10?2.5) particulate samples with the inflammatory activity in the mouse lung. The particulate samples were collected during selected seasons in six European cities using a high-volume cascade impactor. Healthy C57BL/6J mice were intratracheally instilled with a single dose (10 mg/kg) of the particulate samples. At 4, 12, and 24 h after the exposure, the lungs were lavaged and the bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation and tissue damage: cell number, total protein, and cytokines (tumor necrosis factor [TNF]-α, interleukin [IL]-6, and KC). Dicarboxylic acids and transition metals, especially Ni and V, in PM_2.5?0.2 correlated positively and some secondary inorganic ions (NO₃^-, NH₄⁺) negatively with the inflammatory activity. Total organic matter and SO₄^2- had no consistent correlations. In addition, the soil-derived constituents (Ca²⁺, Al, Fe, Si) showed positive correlations with the PM_2.5?0.2-induced inflammatory activity, but their role in PM_10?2.5 remained obscure, possibly due to largely undefined biogenic material. Markers of poor biomass and coal combustion, i.e., monosaccharide anhydrides and As, were associated with elevated PAH contents in PM_2.5?0.2 and a consistent immunosuppressive effect. Overall, our results support epidemiological findings that the local sources of incomplete combustion and resuspended road dust are important in urban air particulate pollution-related health effects.     

Association between fine particulate air pollution and hospital admissions for chest pain in a subtropical city: Taipei,Taiwan

This study determined the association between fine particles (PM_2.5) levels and hospital admissions for chest pain (CP) in Taipei, Taiwan. Hospital admissions for CP and ambient air pollution data for Taipei were obtained for the period 2009–2013. The relative risk of hospital admissions was estimated using a case-crossover approach, after controlling for weather variables, day of the week, seasonality, and long-term time trends. For single-pollutant models (without adjustment for other pollutants), increased frequency of CP admissions was significantly associated with PM_2.5 levels on warm days (>23°C), with an interquartile range rise correlated with a 15% (95% confidence interval = 11–31%) elevation in number of CP admissions. In two-pollutant models, PM_2.5 remained significant after inclusion of each of the other four pollutants: sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃) on warm days. Generally, no marked associations were observed between PM_2.5 levels and risk of CP admissions on cool days in both single- and two-pollutant models. This study provides evidence that higher PM_2.5 concentrations enhance the risk of hospital admissions for CP on warm days.     

AIR PARTICULATE POLLUTION AND HOSPITAL ADMISSIONS FOR CHRONIC OBSTRUCTIVE PULMONARY DISEASE IN RENO,NEVADA

This study assessed the association between ambient PM₁₀ pollution and daily hospital admissions for chronic obstructive pulmonary disease (COPD) in Reno-Sparks, Nevada, for the period 1990-1994. All three hospitals in the region were included. There was a total of 3115 admissions for COPD during this period. Daily ambient PM₁₀ values were available from one of seven air monitoring stations in this region. Weather variables including temperature and wind speed were also collected from this station. The daily average concentration of PM₁₀ was 36.55 mu g/m³. The generalized additive model (GAM) was used in the whole analysis. After adjusting for the effects of weather variables, day of week, seasons, and time trend, the results show that PM₁₀ is a statistically significant predictor for daily hospital admissions for COPD. The relative risk (RR) of hospital admissions for COPD for an interquartile increase (26.6 mu g/m³) of the 24-h average level of PM₁₀ is 1.049 (95% CI 1.011-1.087).     

p53-Dependent apoptosis induced in human bronchial epithelial (16-HBE) cells by PM2.5 sampled from air in Guangzhou,China

Epidemiological studies have shown that air pollution particulate matter (PM) is associated with increased respiratory morbidity and mortality. However, the mechanisms are not fully understood. Oxidative stress-mediated apoptosis plays an important role in the occurrence of respiratory diseases. In this study, human bronchial epithelial (16-HBE) cells were exposed to different concentrations (16–128?µg/ml) of PM_2.5 for 24?h to investigate the apoptosis induced by PM_2.5. The results showed that PM_2.5 exposure significantly induced apoptosis, DNA strand breaks, and oxidative damage in a dose-dependent manner in 16-HBE cells. The expression of p53 and p73 increased significantly along with the dose of PM_2.5 in 16-HBE cells, whereas the expression of p21^Cip1/WAF1 decreased; the expression of mdm2 increased and then decreased, but not significantly. Taken together, these observations indicate that PM_2.5 may lead to oxidative damage and induce apoptosis through the p53-dependent pathway in 16-HBE cells. p53-dependent apoptosis mediated by DNA strand breaks may be an important mechanism of PM_2.5-induced apoptosis in 16-HBE cells.     

Seasonal variation in the toxicological properties of size-segregated indoor and outdoor air particulate matter

Ambient air particulate matter (PM) as well as microbial contaminants in the indoor air are known to cause severe adverse health effects. It has been shown that there is a clear seasonal variation in the potency of outdoor air particles to evoke inflammation and cytotoxicity. However, the role of outdoor sources in the indoor air quality, especially on its toxicological properties, remains largely unknown. In this study, we collected size segregated (PM_10–2.5, PM_2.5–0.2 and PM_0.2) particulate samples with a high volume cascade impactor (HVCI) on polyurethane foam and fluoropore membrane filters. The samples were collected during four different seasons simultaneously from indoor and outdoor air. Thereafter, the samples were weighed and extracted with methanol from the filters before undergoing toxicological analyses. Mouse macrophages (RAW264.7) were exposed to particulate sample doses of 50, 150 and 300 μg/ml for 24 h. Thereafter, the levels of the proinflammatory cytokine (TNF-α), NO-production, cytotoxicity (MTT-test) and changes in the cell cycle (SubG₁, G₁, S and G₂/M phases) were investigated. PM_10–2.5 particles evoked the highest inflammatory and cytotoxic responses. Instead, PM_2.5–0.2 samples exerted the greatest effect on apoptotic activity in the macrophages. With respect to the outdoor air samples, particles collected during warm seasons had a stronger potency to induce inflammatory and cytotoxic responses, whereas no such clear effect was seen with the corresponding indoor air samples. Outdoor air samples were associated with higher inflammatory potential, whereas indoor air samples had overall higher cytotoxic properties. This indicates that the outdoor air has a limited influence on the indoor air quality in a modern house. Thus, the indoor sources dominate the toxicological responses obtained from samples collected inside house.     

Inflammation and tissue damage in mouse lung by single and repeated dosing of urban air coarse and fine particles collected from six European cities

The authors have previously demonstrated heterogeneities in the inflammatory activities of urban air fine (PM_2.5–0.2) and coarse (PM_10–2.5) particulate samples collected from six European cities with contrasting air pollution situations. The same samples (10?mg/kg) were intratracheally instilled to healthy C57BL/6J mice either once or repeatedly on days 1, 3, and 6 of the study week. The lungs were lavaged 24?h after the single dose or after the last repeated dosing. In both size ranges, repeated dosing of particles increased the total cell number in bronchoalveolar lavage fluid (BALF) more than the respective single dose, whereas cytokine concentrations were lower after repeated dosing. The lactate dehydrogenase (LDH) responses increased up to 2-fold after repeated dosing of PM_2.5–0.2 samples and up to 6-fold after repeated dosing of PM_10–2.5 samples. PM_10–2.5 samples evoked a more extensive interstitial inflammation in the mouse lungs. The constituents with major contributions to the inflammatory responses were oxidized organic compounds and transition metals in PM_2.5–0.2 samples, Cu and soil minerals in PM_10–2.5 samples, and Zn in both size ranges. In contrast, poor biomass and coal combustion were associated with elevated levels of polycyclic aromatic hydrocarbons (PAHs) and a consistent inhibitory effect on the inflammatory activity of PM_2.5–0.2 samples. In conclusion, repeated intratracheal instillation of both fine and coarse particulate samples evoked enhanced pulmonary inflammation and cytotoxicity compared to single-dose administration. The sources and constituents of urban air particles responsible for these effects appear to be similar to those encountered in the authors’ previous single-dose study.