Kayo Ueda

Long-range transported Asian Dust and emergency ambulance dispatches

Asian Dust (AD) particles transported from source areas contribute to sharp increases in coarse particles in Japan. We examined the association of exposure to AD events with emergency ambulance dispatches in Nagasaki city. We also examined whether AD transported at different altitude routes from source areas influenced dispatch rates. Using lidar (light detection and ranging), we determined moderate AD days (0.066/km <dust extinction coefficient ≤0.105/km) and heavy AD days (0.105/km <dust extinction coefficient). We applied a time-stratified case-crossover analysis to estimate the association between AD days and emergency ambulance dispatches. There were 9,070 dispatches from March to May during 2003–2007. The heavy AD events at cumulative lag0–3 were associated with an increase in emergency dispatches due to all causes by 12.1% (95% confidence interval (CI), 2.3, 22.9) and an increase for those due to cardiovascular diseases by 20.8% (95% CI: 3.5, 40.9). We categorized 31 AD days based on backward trajectory analyses into AD days with lower altitude routes and those with higher altitude routes. We observed a greater increase in emergency ambulance dispatches on AD days with lower altitude routes compared with those on AD days with higher altitude routes although the difference was not significant (p for interaction 0.49). These results have shown that exposure to high AD particle levels could increase emergency ambulance dispatches due to illnesses such as cardiovascular stress, and that AD traveling through different routes may have different health effects.

Estimating Mortality Effects of Fine Particulate Matter in Japan: A Comparison of Time-Series and Case-Crossover Analyses

Abstract Small particles can reach alveoli without being trapped in the upper respiratory tract and may have a greater impact on health than larger particles. Given the limited knowledge on health effects of fine particulate matter (PM2.5) in Japan, the short-term effects of PM2.5 on daily mortality using the generalized additive model (GAM), generalized linear model (GLIM), and time-stratified case-crossover analysis were estimated. Daily mortality data were obtained from the Ministry of Health, Labor, and Welfare. Air pollution and meteorological data in 20 areas were obtained from the National Institute for Environmental Studies and the Japan Meteorological Agency, respectively. The three methods were compared, adjusting for meteorological variables and co-pollutants, for area-specific analyses and combined area-specific results using meta-analysis with a random-effects model. Daily mortality for elderly aged 65 and over varied from 0.5 to 127.3 by area. The 24-hr mean concentration of PM2.5 ranged from 11.8 to 22.8 μg/m3. Area-specific analyses revealed regional heterogeneity. Furthermore, combined results showed that a 10-μg/m3 increase in PM2.5 for the single-pollutant model at lag1 was associated with a 0.53, 0.77, and 0.88% increase in all-cause mortality for the GAM, GLIM, and case-crossover analysis, respectively. These findings provide robust evidence for the short-term effects of air pollutants on daily mortality in Japan and suggest that differences in estimates obtained from different statistical models should be considered when multipollutant models are used.

Impact of short-term exposure to fine particulate matter on emergency ambulance dispatches in Japan

Background Evidence of an association between fine particulate matter (PM2.5) and morbidity is limited in Asia. We used a case-crossover design to evaluate the association between short-term exposure to PM2.5 and emergency ambulance dispatches (as a proxy of acute health outcomes), and to calculate the extent to which a 10 μg/m3 decrease in PM2.5 concentrations would reduce the number of ambulance dispatches. Methods We used data on emergency ambulance dispatches in Fukuoka City, Japan between 2005 and 2010. Emergency ambulance services are publicly funded and cover the entire city. After excluding ambulance dispatches related to external injuries and pregnancy/childbirth, we analysed data on the remaining 176 123 dispatches. We also collected records of daily concentrations of PM2.5 from one ambient air pollution monitoring station. ORs per 10 μg/m3 increase in PM2.5 were estimated using conditional logistic regression controlled for ambient temperature and relative humidity. Results During the study period, the average daily concentration of PM2.5 was 20.3 μg/m3. Exposure to PM2.5 was associated with emergency ambulance dispatches in general (lag0–1; OR=1.008 (95% CI 1.002 to 1.014)) and with dispatches due to respiratory diseases (lag0–1; OR=1.027 (1.007 to 1.048)). No association was observed for dispatches due to cardiovascular diseases. We estimated that a 10 μg/m3 decrease in PM2.5 concentrations would have led to approximately 260 (estimated range=70–460) fewer ambulance dispatches in Fukuoka for 2012. Conclusions Providing further evidence on the short-term health effects of PM2.5 exposure, we found that exposure was associated with an increased number of emergency ambulance dispatches. The effect was, however, relatively small.

Relationship Between Asian Dust and Ischemic Stroke A Time-Stratified Case-Crossover Study

Background and Purpose– Particulate matter is increasingly recognized as a cause of human diseases, including cardiovascular diseases. However, the association between Asian dust (AD), a windblown sand dust originating from mineral soil in the deserts of China and Mongolia, and the incidence of cardiovascular diseases is unclear. The aim of the present study was to elucidate whether AD is associated with the incidence of ischemic stroke. Methods– This study investigated the onset time of 7429 consecutive patients with ischemic stroke who were admitted to seven stroke centers in Fukuoka, Japan, between June 1999 and March 2010. Meteorologic variables and air pollutants, including AD and suspended particulate matters, were investigated during the identical period. A time-stratified case-crossover study was conducted to assess the association between AD and stroke incidence using a conditional logistic regression analysis. Results– Although AD was not significantly associated with the overall incidence of ischemic stroke, there was a relationship specific to the stroke subtypes. AD was significantly associated with the incidence of atherothrombotic brain infarction after adjusting for expected confounders, including meteorologic variables and other air pollutants. No association was detected in other types of ischemic stroke. Conclusion– These data suggest that AD does not increase the overall incidence of ischemic stroke, but it is specifically associated with the risk of atherothrombotic brain infarction.

Particulate matter modifies the association between airborne pollen and daily medical consultations for pollinosis in Tokyo

Pollen from Japanese cedar (sugi) and cypress (hinoki) trees is responsible for the growing prevalence of allergic rhinitis, especially pollinosis in Japan. Previous studies have suggested that air pollutants enhance the allergic response to pollen in susceptible individuals. We conducted a time-stratified case-crossover study to examine the potential modifying effects of PM2.5 and suspended particulate matter (SPM) on the association between pollen concentration and daily consultations for pollinosis. A total of 11,713 daily pollinosis cases (International Classification of Diseases, ICD-10, J30.1) from January to May, 2001-2011, were obtained from a clinic in Chiyoda, Tokyo. Daily pollen counts and the daily mean values of air pollutants (PM2.5, SPM, SO2, NO2, CO, and O3) were collected from monitoring stations across Tokyo. The effects of pollen were stratified by the level of PM2.5 and SPM to examine the interaction effect of pollen and particulate pollutants. We found a statistically significant interaction between pollen concentration and PM2.5/SPM. On days with a high level of PM2.5 (>95th percentile), an interquartile increase in the mean cumulative pollen count (an average of 28 pollen grains per cm(2) during lag-days 0 to 5) corresponded to a 10.30% (95%CI: 8.48%-12.16%) increase in daily new pollinosis cases, compared to 8.04% (95%CI: 7.28%-8.81%) on days with a moderate level of PM2.5 (5th-95th percentile). This interaction persisted when different percentile cut-offs were used and was robust to the inclusion of other air pollutants. A similar interaction pattern was observed between SPM and pollen when a less extreme cut-off for SPM was used to stratify the effect of pollen. Our study showed the acute effect of pollen was greater when the concentration of air particulate pollutant, specifically PM2.5 and SPM, was higher. These findings are consistent with the notion that particulate air pollution may act as an adjuvant that promotes allergic disease (i.e. pollinosis).

Short-term exposure to air pollution and incidence of stroke and acute myocardial infarction in a Japanese population.

Background: Exposure to high levels of air pollution can increase the risk of cardiovascular events. However, there is no clear information in Japan on the effect of pollution on the incidence of stroke and acute myocardial infarction (AMI). Therefore, we investigated the effects of air pollution on the incidence of stroke and AMI in a setting where pollutant levels are rather low. Methods: Data were obtained from the Takashima Stroke and AMI Registry, which covers a population of approximately 55,000 in Takashima County in central Japan. We applied a time-stratified, bidirectional, case-crossover design to estimate the effects of air pollutants, which included suspended particulate matter (SPM), sulfur dioxide (SO2), nitrogen dioxide (NO2) and photochemical oxidants (Ox). We used the distributed lag model to estimate the effect of pollutant exposure 0-3 days before the day of event onset and controlled for meteorological covariates in all of the models. Results: There were 2,038 first-ever strokes (1,083 men, 955 women) and 429 first-ever AMI cases (281 men, 148 women) during 1988-2004. The mean pollutant levels were as follows: SPM 26.9 µg/m3; SO2 3.9 ppb; NO2 16.0 ppb, and Ox 28.4 ppb. In single-pollutant and two-pollutant models, SO2 was associated with the risk of cerebral hemorrhage. Other stroke subtypes and AMI were not associated with air pollutant levels. Conclusions: We observed an association between SO2 and hemorrhagic stroke; however, we found inconclusive evidence for a short-term effect of air pollution on the incidence of other stroke types and AMI.

Desert Dust Is a Risk Factor for the Incidence of Acute Myocardial Infarction in Western Japan

Background—Recently, there has been increasing concern about adverse health effects of exposure to desert dust events. However, the association between dust and the incidence of ischemic heart diseases is unknown. The aim of the present study was to elucidate whether Asian dust (AD), a windblown sand dust originating from mineral soil in China and Mongolia, is associated with the incidence of acute myocardial infarction (AMI). Methods and Results—We investigated the data regarding hospitalization because of AMI among 3068 consecutive patients from 4 AMI centers in Fukuoka, Japan, and data for AD from April 2003 to December 2010. We applied a time-stratified case-crossover design to examine the association between AD and the incidence of AMI. Using a conditional logistic regression analysis, we estimated the odds ratios of AMI associated with AD after controlling for ambient temperature and relative humidity. The occurrence of AD events 0 to 4 days before the day of admission was significantly associated with the incidence of AMI. In particular, the occurrence of AD 4 days before admission was significantly associated with the onset of AMI. Conclusions—These data suggest that exposure to AD a few days before symptom onset is associated with the incidence of AMI.

Ambient air pollutants and acute case-fatality of cerebro-cardiovascular events: Takashima Stroke and AMI Registry, Japan (1988-2004).

Background: Apart from the conventional risk factors, cerebro-cardiovascular disease (CVD) are also reported to be associated with air pollution, thus lowering the level of exposure might contribute in prevention activities to reduce the associated adverse outcomes. Though few studies conducted in Japan have reported on the CVD mortality but none have explored the effect of air pollutant exposure on the acute case-fatality of CVD. We investigated the effects of air pollution exposure on acute case-fatality of stroke and acute myocardial infarction (AMI) in a setting where pollutant levels are rather low. Methods: We leveraged the data from the Takashima Stroke and AMI Registry, which covers a population of approximately 55,000 in Takashima County located in central Japan. The study period of 6,210 days (16 years, leap years also taken into account) were divided into quartiles of daily average pollutant concentration; suspended particulate matter (SPM), sulfur dioxide (SO2), nitrogen dioxide (NO2), and photochemical oxidants (Ox). The stroke and AMI events were categorized to corresponding quartiles based on the pollution levels of the onset day. To study the effects of air pollutants, we estimated the fatality rate ratio across quartiles of the pollutants where the lowest quartile served as the reference. Results: There were 307 (men: 153 and women: 154) fatal stroke cases within 28 days of onset among the 2,038 first ever stroke during 1988–2004. In the same period, there were 142 (men: 94 and women: 54) fatal AMI cases within 28 days of onset among the 429 first ever AMI events. The mean of the measured pollutant levels were as follows: SPM 26.9 µg/m3, SO2 3.9 ppb, NO2 16.0 ppb, and Ox 28.4 ppb. Among the pollutants, higher levels of NO2 showed increased fatality risk. In multi-pollutant model, the highest quartile of NO2 was associated with 60% higher stroke case-fatality risk in comparison to lowest quartile of NO2. In the fully adjusted model the fatality-rate ratio was 1.65 (95% CI 1.06–2.57). This association was more prominent among stroke subtype of cerebral infarction. Other pollutant levels did not show any association with stroke or AMI case-fatality. Conclusion: We observed association between NO2 levels, an index of traffic related air pollution, with the acute case-fatality of stroke, especially cerebral infarction in our study population. Further studies are needed in different regions to determine the association between ambient air pollutants and acute cardiovascular fatalities.

Asian dust exposure triggers acute myocardial infarction

Aims To elucidate whether Asian dust is associated with the incidence of acute myocardial infarction (AMI) and to clarify whether patients who are highly sensitive to Asian dust will develop AMI. Methods and results Twenty-one participating institutions located throughout Kumamoto Prefecture and capable of performing coronary intervention were included in the study. Data for ground-level observations of Asian dust events were measured at the Kumamoto Local Meteorological Observatory. Data collected between 1 April 2010 and 31 March 2015 were analysed, and 3713 consecutive AMI patients were included. A time-stratified case-crossover design was applied to examine the association between Asian dust exposure and AMI. The occurrence of Asian dust events at 1 day before the onset of AMI was associated with the incidence of AMI [odds ratio (OR), 1.46; 95% confidence interval (CI), 1.09-1.95] and especially, non-ST-segment elevation myocardial infarction was significant (OR 2.03; 95% CI, 1.30-3.15). A significant association between AMI and Asian dust was observed in patients with age ≥75 years, male sex, hypertension, diabetes mellitus, never-smoking status, and chronic kidney disease (CKD). However, Asian dust events had a great impact on AMI onset in patients with CKD (P < 0.01). A scoring system accounting for several AMI risk factors was developed. The occurrence of Asian dust events was found to be significantly associated with AMI incidence among patients with a risk score of 5-6 (OR 2.45; 95% CI: 1.14-5.27). Conclusion Asian dust events may lead to AMI and have a great impact on its onset in patients with CKD.

Aerosol Health Effects from Molecular to Global Scales

Poor air quality is globally the largest environmental health risk. Epidemiological studies have uncovered clear relationships of gaseous pollutants and particulate matter (PM) with adverse health outcomes, including mortality by cardiovascular and respiratory diseases. Studies of health impacts by aerosols are highly multidisciplinary with a broad range of scales in space and time. We assess recent advances and future challenges regarding aerosol effects on health from molecular to global scales through epidemiological studies, field measurements, health-related properties of PM, and multiphase interactions of oxidants and PM upon respiratory deposition. Global modeling combined with epidemiological exposure-response functions indicates that ambient air pollution causes more than four million premature deaths per year. Epidemiological studies usually refer to PM mass concentrations, but some health effects may relate to specific constituents such as bioaerosols, polycyclic aromatic compounds, and transition metals. Various analytical techniques and cellular and molecular assays are applied to assess the redox activity of PM and the formation of reactive oxygen species. Multiphase chemical interactions of lung antioxidants with atmospheric pollutants are crucial to the mechanistic and molecular understanding of oxidative stress upon respiratory deposition. The role of distinct PM components in health impacts and mortality needs to be clarified by integrated research on various spatiotemporal scales for better evaluation and mitigation of aerosol effects on public health in the Anthropocene.