Short-term mortality rates during a decade of improved air quality in Erfurt, Germany

Accountability analysis of health benefits related to National Action Plan on Air Pollution Prevention and Control in China

China is one of the largest producers and consumers of coal in the world. The National Action Plan on Air Pollution Prevention and Control in China (2013-2017) particularly aimed to reduce emissions from coal combustion. Here, we show whether the acute health effects of PM2.5 changed from 2013 to 2018 and factors that might account for any observed changes in the Beijing-Tianjin-Hebei (BTH) and the surrounding areas where there were major reductions in PM2.5 concentrations. We used a two-stage analysis strategy, with a quasi-Poisson regression model and a random effects meta-analysis, to assess the effects of PM2.5 on mortality in the 47 counties of BTH. We found that the mean daily PM2.5 levels and the SO42- component ratio dramatically decreased in the study period, which was likely related to the control of coal emissions. Subsequently, the acute effects of PM2.5 were significantly decreased for total and circulatory mortality. A 10 μg/m3 increase in PM2.5 concentrations was associated with a 0.16% (95% CI: 0.08, 0.24%) and 0.02% (95% CI: -0.09, 0.13%) increase in mortality from 2013 to 2015 and from 2016 to 2018, respectively. The changes in air pollution sources or PM2.5 components appeared to have played a core role in reducing the health effects. The air pollution control measures implemented recently targeting coal emissions taken in China may have resulted in significant health benefits.

Modification of heat-related effects on mortality by air pollution concentration, at small-area level, in the Attica prefecture, Greece

BACKGROUND

The independent effects of short-term exposure to increased air temperature and air pollution on mortality are well-documented. There is some evidence indicating that elevated concentrations of air pollutants may lead to increased heat-related mortality, but this evidence is not consistent. Most of these effects have been documented through time-series studies using city-wide data, rather than at a finer spatial level. In our study, we examined the possible modification of the heat effects on total and cause-specific mortality by air pollution at municipality level in the Attica region, Greece, during the warm period of the years 2000 to 2016.

METHODS

A municipality-specific over-dispersed Poisson regression model during the warm season (May-September) was used to investigate the heat effects on mortality and their modification by air pollution. We used the two-day average of the daily mean temperature and daily mean PM10, NO2 and 8 hour-max ozone (O3), derived from models, in each municipality as exposures. A bivariate tensor smoother was applied for temperature and each pollutant alternatively, by municipality. Α random-effects meta-analysis was used to obtain pooled estimates of the heat effects at different pollution levels. Heterogeneity of the between-levels differences of the heat effects was evaluated with a Q-test.

RESULTS

A rise in mean temperature from the 75th to the 99th percentile of the municipality-specific temperature distribution resulted in an increase in total mortality of 12.4% (95% Confidence Interval (CI):7.76-17.24) on low PM10 days, and 21.25% (95% CI: 17.83-24.76) on high PM10 days. The increase on mortality was 10.09% (95% CI: - 5.62- 28.41) on low ozone days, and 14.95% (95% CI: 10.79-19.27) on high ozone days. For cause-specific mortality an increasing trend of the heat effects with increasing PM10 and ozone levels was also observed. An inconsistent pattern was observed for the modification of the heat effects by NO2, with higher heat effects estimated in the lower level of the pollutant.

CONCLUSIONS

Our results support the evidence of elevated heat effects on mortality at higher levels of PM10 and 8 h max O3. Under climate change, any policy targeted at lowering air pollution levels will yield significant public health benefits.

Modelling variations of emergency attendances using data on community mobility, climate and air pollution

Air pollution is associated with morbidity and mortality worldwide. We investigated the impact of improved air quality during the economic lockdown during the SARS-Cov2 pandemic on emergency room (ER) admissions in Germany. Weekly aggregated clinical data from 33 hospitals were collected in 2019 and 2020. Hourly concentrations of nitrogen and sulfur dioxide (NO2, SO2), carbon and nitrogen monoxide (CO, NO), ozone (O3) and particulate matter (PM10, PM2.5) measured by ground stations and meteorological data (ERA5) were selected from a 30 km radius around the corresponding ED. Mobility was assessed using aggregated cell phone data. A linear stepwise multiple regression model was used to predict ER admissions. The average weekly emergency numbers vary from 200 to over 1600 cases (total n = 2,216,217). The mean maximum decrease in caseload was 5 standard deviations. With the enforcement of the shutdown in March, the mobility index dropped by almost 40%. Of all air pollutants, NO2 has the strongest correlation with ER visits when averaged across all departments. Using a linear stepwise multiple regression model, 63% of the variation in ER visits is explained by the mobility index, but still 6% of the variation is explained by air quality and climate change.

Impact of Ambient Ultrafine Particles on Cause-Specific Mortality in Three German Cities

Rationale: Exposure to ambient air pollution has been associated with adverse effects on morbidity and mortality. However, the evidence for ultrafine particles (UFPs; 10-100 nm) based on epidemiological studies remains scarce and inconsistent. Objectives: We examined associations between short-term exposures to UFPs and total particle number concentrations (PNCs; 10-800 nm) and cause-specific mortality in three German cities: Dresden, Leipzig, and Augsburg. Methods: We obtained daily counts of natural, cardiovascular, and respiratory mortality between 2010 and 2017. UFPs and PNCs were measured at six sites, and measurements of fine particulate matter (PM2.5; ⩽2.5 μm in aerodynamic diameter) and nitrogen dioxide were collected from routine monitoring. We applied station-specific confounder-adjusted Poisson regression models. We investigated air pollutant effects at aggregated lags (0-1, 2-4, 5-7, and 0-7 d after UFP exposure) and used a novel multilevel meta-analytical method to pool the results. Additionally, we assessed interdependencies between pollutants using two-pollutant models. Measurements and Main Results: For respiratory mortality, we found a delayed increase in relative risk of 4.46% (95% confidence interval, 1.52 to 7.48%) per 3,223-particles/cm3 increment 5-7 days after UFP exposure. Effects for PNCs showed smaller but comparable estimates consistent with the observation that the smallest UFP fractions showed the largest effects. No clear associations were found for cardiovascular or natural mortality. UFP effects were independent of PM2.5 in two-pollutant models. Conclusions: We found delayed effects for respiratory mortality within 1 week after exposure to UFPs and PNCs but no associations for natural or cardiovascular mortality. This finding adds to the evidence on the independent health effects of UFPs.

Using Parametric g-Computation to Estimate the Effect of Long-Term Exposure to Air Pollution on Mortality Risk and Simulate the Benefits of Hypothetical Policies: The Canadian Community Health Survey Cohort (2005 to 2015)

BACKGROUND

Numerous epidemiological studies have documented the adverse health impact of long-term exposure to fine particulate matter [particulate matter ≤2.5μm in aerodynamic diameter (PM2.5)] on mortality even at relatively low levels. However, methodological challenges remain to consider potential regulatory intervention's complexity and provide actionable evidence on the predicted benefits of interventions. We propose the parametric g-computation as an alternative analytical approach to such challenges.

METHOD

We applied the parametric g-computation to estimate the cumulative risks of nonaccidental death under different hypothetical intervention strategies targeting long-term exposure to PM2.5 in the Canadian Community Health Survey cohort from 2005 to 2015. On both relative and absolute scales, we explored the benefits of hypothetical intervention strategies compared with the natural course that a) set the simulated exposure value at each follow-up year to a threshold value if exposure was above the threshold (8.8 μg/m3, 7.04 μg/m3, 5 μg/m3, and 4 μg/m3), and b) reduced the simulated exposure value by a percentage (5% and 10%) at each follow-up year. We used the 3-y average PM2.5 concentration with 1-y lag at the postal code of respondents' annual mailing addresses as their long-term exposure to PM2.5. We considered baseline and time-varying confounders, including demographics, behavior characteristics, income level, and neighborhood socioeconomic status. We also included the R syntax for reproducibility and replication.

RESULTS

All hypothetical intervention strategies explored led to lower 11-y cumulative mortality risks than the estimated value under the natural course without intervention, with the smallest reduction of 0.20 per 1,000 participants (95% CI: 0.06, 0.34) under the threshold of 8.8 μg/m3, and the largest reduction of 3.40 per 1,000 participants (95% CI: -0.23, 7.03) under the relative reduction of 10% per interval. The reductions in cumulative risk, or numbers of deaths that would have been prevented if the intervention was employed instead of maintaining the status quo, increased over time but flattened toward the end of the follow-up period. Estimates among those ≥65 years of age were greater with a similar pattern. Our estimates were robust to different model specifications.

DISCUSSION

We found evidence that any intervention further reducing the long-term exposure to PM2.5 would reduce the cumulative mortality risk, with greater benefits in the older population, even in a population already exposed to low levels of ambient PM2.5. The parametric g-computation used in this study provides flexibilities in simulating real-world interventions, accommodates time-varying exposure and confounders, and estimates adjusted survival curves with clearer interpretation and more information than a single hazard ratio, making it a valuable analytical alternative in air pollution epidemiological research. https://doi.org/10.1289/EHP11095.

Temporal Heterogeneity of Short-Term Effects of Particulate Matter on Stroke Outpatients in Seven Major Cities of the Republic of Korea

Although particulate matter (PM) is a major risk factor for stroke, its effects on hospital outpatients admitted for stroke have not been documented in Korea. In addition, recent studies have reported that the effects of PM₁₀ on circulatory mortality changed over time. We aimed to estimate the effects of PM₁₀ on stroke and their temporal heterogeneity in seven major cities of Korea during the period 2002-2015. The study period was divided into five years of moving time windows, and city-specific PM₁₀ effects on ischemic and hemorrhagic stroke outpatients were calculated. We pooled the estimates using meta-analysis and plotted them into a sequence to identify their temporal trends. A 10 µg/m³ increase of PM₁₀ was significantly associated with increments in hospital outpatients admitted for ischemic stroke (0.24%, 95% CI: 0.04%, 0.44%), but not for hemorrhagic stroke (0.33%, 95% CI: -0.06%, 0.73%). Effect estimates for strokes increased during the period 2003-2013 but decreased after. For the first time, we have estimated the effects of PM₁₀ on hospital outpatients admitted for stroke in Korea. The observed temporal trend in PM₁₀ effects was similar to patterns of circulatory mortality, suggesting that the temporal heterogeneity in PM₁₀ effects might be due to systematic causes rather than random fluctuations.

Do temporal trends of associations between short-term exposure to fine particulate matter (PM2.5) and risk of hospitalizations differ by sub-populations and urbanicity-a study of 968 U.S. counties and the Medicare population

While associations between short-term exposure to fine particulate matter (PM_2.5) and risk of hospitalization are well documented and evidence suggests that such associations change over time, it is unclear whether these temporal changes exist in understudied less-urban areas or differ by sub-population. We analyzed daily time-series data of 968 continental U.S. counties for 2000-2016, with cause-specific hospitalization from Medicare claims and population-weighted PM_2.5 concentrations originally estimated at 1km × 1 km from a hybrid model. Circulatory and respiratory hospitalizations were categorized based on primary diagnosis codes at discharge. Using modified Bayesian hierarchical modelling, we evaluated the temporal trend in association between PM_2.5 and hospitalizations and whether disparities in this trend exist across individual-level characteristics (e.g., sex, age, race, and Medicaid eligibility as a proxy for socio-economic status) and urbanicity. Urbanicity was categorized into three levels by county-specific percentage of urban population based on urban rural delineation from the U.S. Census. In this cohort with understudied less-urban areas without regulatory monitors, we still found positive association between circulatory and respiratory hospitalization and short-term exposure to PM_2.5, with higher effect estimates towards the end of study period. Consistent with current literature, we identified significant disparity in associations by race, socioeconomic status and urbanicity. We found that the percentage change in circulatory hospitalization rate per 10 μg/m³ increase in PM_2.5 was higher in the 2008-2016 time period compared to the 2000-2007 period by 0.33% (95% posterior credible interval 0.22, 0.44%), 0.52% (0.33, 0.69%), and 0.67% (0.53, 0.83%) for low, medium and high tertiles of urban areas, respectively. We also observed significant differences in temporal trends of associations across socioeconomic status, sex, and age, indicating a possible widening in disparity of PM_2.5-related health burden. This study raises the importance of considering environmental justice issues in PM_2.5-related health impacts with respect to how associations may change over time.

Critical Periods, Critical Time Points and Day-of-the-Week Effects in COVID-19 Surveillance Data: An Example in Middlesex County, Massachusetts, USA

Critical temporal changes such as weekly fluctuations in surveillance systems often reflect changes in laboratory testing capacity, access to testing or healthcare facilities, or testing preferences. Many studies have noted but few have described day-of-the-week (DoW) effects in SARS-CoV-2 surveillance over the major waves of the novel coronavirus 2019 pandemic (COVID-19). We examined DoW effects by non-pharmaceutical intervention phases adjusting for wave-specific signatures using the John Hopkins University’s (JHU’s) Center for Systems Science and Engineering (CSSE) COVID-19 data repository from 2 March 2020 through 7 November 2021 in Middlesex County, Massachusetts, USA. We cross-referenced JHU’s data with Massachusetts Department of Public Health (MDPH) COVID-19 records to reconcile inconsistent reporting. We created a calendar of statewide non-pharmaceutical intervention phases and defined the critical periods and timepoints of outbreak signatures for reported tests, cases, and deaths using Kolmogorov-Zurbenko adaptive filters. We determined that daily death counts had no DoW effects; tests were twice as likely to be reported on weekdays than weekends with decreasing effect sizes across intervention phases. Cases were also twice as likely to be reported on Tuesdays-Fridays (RR = 1.90–2.69 [95%CI: 1.38–4.08]) in the most stringent phases and half as likely to be reported on Mondays and Tuesdays (RR = 0.51–0.93 [0.44, 0.97]) in less stringent phases compared to Sundays; indicating temporal changes in laboratory testing practices and use of healthcare facilities. Understanding the DoW effects in daily surveillance records is valuable to better anticipate fluctuations in SARS-CoV-2 testing and manage appropriate workflow. We encourage health authorities to establish standardized reporting protocols.

Temporal variations of short-term associations between PM10 and NO2 concentrations and emergency department visits in Shanghai, China 2008-2019

Levels and constituents of ambient air pollution have substantially changed in China over the last decade. Such changes may lead to the variations in health effects of air pollution. Very limited studies, however, have investigated the temporal variations in health effects of air pollution on a long-term scale, especially in China. We evaluated the temporal variations in short-term associations between PM₁₀ and NO₂ concentrations and emergency department (ED) visits during a 12-year period from 2008 to 2019 in Shanghai, China. A quasi-Poisson generalized linear regression was performed to assess the associations between PM₁₀ and NO₂ concentrations and ED visits during entire study period and three specific periods. We evaluated the temporal variations of period-specific associations with an interaction variable between pollutant concentrations and period indicators. We further investigated the concentration-response relationships for specific periods. The effects on specific subpopulations (males and females; 18-65 years old and >65 years old) were also examined. A 10 μg/m³ increase of PM₁₀ and NO₂ corresponded to 0.48% (95% CI: 0.36%, 0.59%) and 1.51% (95% CI: 1.25%, 1.78%) increase in ED visits at lag0-7 day for entire study period, respectively. The short-term associations between ED visits and NO₂ remained unchanged over time (P-value > 0.05), while the effects from PM₁₀ were significantly inconsistent (P-value < 0.05), with the highest effect observed during the intermediate period of 2012-2015 and the lowest effect observed during the initial period of 2008-2011. Similar temporal trends were found in subgroups, except for elderly group. Despite substantial reduction in ambient PM₁₀ and NO₂ concentrations, the short-term effects on ED visits for NO₂ remained stable and even increased for PM₁₀. More efforts were needed to reduce harmful components in air pollution mixture to reduce the health hazards of air pollution.

Effects of the implementation of a mass rapid transit system on mortality rates attributed to cardiorespiratory complications in Taipei

Although Taipei City has encountered a fall in ambient air pollutant levels since 1996, the year its mass rapid transit (MRT) system commenced operation, no apparent study investigated changes in risks of death attributed to respiratory, cardiovascular, and cerebrovascular diseases in Taipei during this 23-year period. In order to examine the relationship between MRT and occurrence of respiratory and cardiovascular illnesses attributed to air contaminants, exposure over the 23 year duration was subdivided into the following periods: reference period 1 (1992-1995); period 2 (1996-2004), a time when there was a total track length of 67 km; period 3 (2005-2015), when the total track length was lengthened to 131.1 km; and period 4 (2016-2020), when it was further extended to 146.2 km. Taichung City, no MRT system, was used as an external reference population. The effect of Taipei's MRT system on rates of cause-specific death rates was analyzed using robust generalized Poisson regression models. After adjusting for age-standardized rates (ASRs), a decrease in relative risks (RRs) was found for non-trauma death and respiratory disease from periods 2 to 4. Even though the RRs were greater than 1.0 for cardiovascular and cerebrovascular diseases for periods 2 to 4, a downward trend was still noted in these RRs in Taipei. These findings suggest a relationship exists between air pollutant exposure and mortality. In addition, data demonstrated that implementation of the MRT in Taipei exerted beneficial health effects as evidenced by lower mortality rates.

Temporal variation in association between short-term exposure to fine particulate matter and hospitalisations in older adults in the USA: a long-term time-series analysis of the US Medicare dataset

BACKGROUND

Short-term exposure to fine particulate matter (PM_2·5) is associated with increased risk of hospital admissions and mortality, and health risks differ by the chemical composition of PM_2·5. Policies to control PM_2·5 could change its chemical composition and total mass concentration, leading to change in the subsequent health impact. However, there is little ence on whether associations between PM_2·5 and health exhibit temporal variation. We investigated whether risks of hospitalisations from short-term exposure to PM_2·5 varied over time in the USA.

METHODS

We did a time-series analysis using a national dataset comprising daily circulatory and respiratory hospitalisation rates of Medicare beneficiaries (age ≥65 years) and PM_2·5 in 173 US counties from 1999 to 2016. We fitted modified quasi-Poisson models to estimate temporal trends of associations within a county, and pooled county-level estimates using Bayesian hierarchical modelling to generate an overall estimate.

FINDINGS

The study included 10 559 654 circulatory and 3 027 281 respiratory hospitalisations. We identified changes in the national average association between previous-day PM_2·5 and respiratory hospitalisation over time, with a U-shape that is robust under stratification, linear, and non-linear models. The change in risk of respiratory hospitalisation per 10 μg/m³ increase in previous-day PM_2·5 decreased from 0·75% (95% posterior credible interval 0·05 to 1·46) in 1999 to -0·28% (-0·79 to 0·23) in 2008, and then increased to 1·44% (0·00 to 2·91) in 2016. No statistically significant temporal change was observed for associations between same-day PM_2·5 and circulatory hospitalisation.

INTERPRETATION

Hospitalisation risk from PM_2·5 changes over time and has increased over the past 7 years in study, especially in northeastern USA. The temporal trend differs by cause of hospitalisation. This study emphasises the necessity of evaluating temporal heterogeneity in health impacts of PM_2·5 and suggests caution in applying association estimates to a different time period.

FUNDING

US Environmental Protection Agency and Yale Institute for Biospheric Studies.

Short-Term Exposure to Ambient Air Pollution and Increased Emergency Room Visits for Skin Diseases in Beijing, China

Skin diseases have become a global concern. This study aims to evaluate the associations between ambient air pollution and emergency room visits for skin diseases under the background of improving air quality in China. Based on 45,094 cases from a general hospital and fixed-site monitoring environmental data from 2014–2019 in Beijing, China, this study used generalized additive models with quasi-Poisson regression to estimate the exposure–health associations at lag 0–1 to lag 0–7. PM_2.5 and NO₂ exposure were associated with increased emergency room visits for total skin diseases (ICD10: L00-L99). Positive associations of PM_2.5, PM₁₀, O₃ and NO₂ with dermatitis/eczema (ICD-10: L20–30), as well as SO₂ and NO₂ with urticaria (ICD-10: L50) visits were also found. For instance, a 10 μg/m³ increase in PM_2.5 was associated with increases of 0.7% (95%CI: 0.2%, 1.2%) in total skin diseases visits at lag 0–5 and 1.1% (95%CI: 0.6%, 1.7%) in dermatitis/eczema visits at lag 0–1, respectively. For PM_2.5, PM₁₀ and CO, stronger annual associations were typically observed in the high-pollution (2014) and low-pollution (2018/2019) years. For instance, a 10 μg/m³ increase in PM_2.5 at lag 0–5 was associated with increases of 1.8% (95%CI: 1.0%, 2.6%) and 2.3% (95%CI: 0.4%, 4.3%) in total skin disease visits in 2014 and 2018, respectively. Our study emphasizes the necessity of controlling the potential health hazard of air pollutants on skin, although significant achievements in air quality control have been made in China.

Change in risk of hospital admissions for ischemic heart disease after the implementation of a mass rapid transit system in Taipei

Numerous epidemiologic studies demonstrated an association between an increase in levels of fine particles (particulate matter less than 2.5 um in diameter, PM_2.5) and elevation in the number of hospital admissions for cardiovascular diseases. Air pollution levels including PM_2.5 clearly decreased in Taipei City after the mass rapid transit (MRT) system began operations in 1996. The aim of this study was to investigate the extent of changes in the risk of daily hospital admissions for ischemic heart disease (IHD) over a 17-year period after the installation of a MRT system in Taipei. The full study was divided into Period 1 (1997-2000), total track length 65.1 km; Period 2 (2001-2008), total track length 75.8 km; and Period 3 (2009-2013), total track length 121.3 km. A time-stratified case-crossover analysis was conducted to estimate relative risk (RR) of hospital admissions for IHD for each 10 ug/m³ increase in PM_2.5 for different periods. On cool days, the associated RR of IHD for Period 3 was consistently lower compared to period 2 in both our single- and two-pollutant models. However, the daily risk for IHD admissions was found to be significantly higher for period 3 compared to period 2 in our single-pollutant model and in our two-pollutant models (PM_2.5+ SO₂) on warm days. The basis for this difference is unknown. Data suggests that an MRT system may provide substantial health benefits, a finding that may be helpful to urban communities, urban planners, and public health specialists.

Increasing cardiopulmonary effects of ultrafine particles at relatively low fine particle concentrations

Ultrafine particles (UFPs) are of concern because of their high pulmonary deposition efficiency. However, present control measures are generally targeted at fine particles (PM_2.5), with little effect on UFPs. The health effects of UFPs at different PM_2.5 concentrations may provide a basic for controlling UFPs but remain unclear in polluted areas. School children spend the majority of their time in the classrooms. This study investigated the different short-term effects of indoor UFPs on school children in Beijing, China when indoor PM_2.5 concentrations exceeded or satisfied the recently published Chinese standard for indoor PM_2.5. Cardiopulmonary functions of 48 school children, of whom 46 completed, were measured three times. Indoor PM_2.5 and UFPs were monitored in classrooms on weekdays. Measurements were separated into two groups according to the abovementioned standard. Mixed-effect models were used to explore the health effects of the air pollutants. Generally, UFP-associated effects on children's cardiopulmonary function persisted even at relatively low PM_2.5 concentrations, especially on heart rate variability indices. The risks associated with high PM_2.5 concentrations are well-known, but the effects of UFPs on children's cardiopulmonary function deserve more attention even when PM_2.5 has been controlled. UFP control and standard setting should therefore be considered.

Temporal variations of short-term effects of particulate matter on hospital admissions in the most densely populated city in Thailand

Short-term effects of ambient particulate matter (PM) on daily hospital admissions have been comprehensively elucidated, but very few studies evaluated the temporal variations of ambient PM associated with hospital admissions, especially in developing countries. This study aimed to explore the temporal changes of the short-term effects of PM₁₀ on hospital admissions in Bangkok, Thailand from 2006 to 2014. The overdispersed Poisson regression model was applied to related daily PM₁₀ concentrations to daily cardiovascular and respiratory hospital admissions by adjusting for temperature, humidity, long-term trend and seasonality, day of the week, public holiday, and population dynamics. The temporal variations of the effects of PM₁₀ on hospital admissions were assessed by adding an interaction term between PM₁₀ concentration and predefined time periods into the model. The relative risks per 10 μg/m³ increase in PM₁₀ were 1.0092 (95% CI: 1.0046, 1.0138) for cardiovascular admissions at lag 0-3 day and 1.0209 (95% CI: 1.0145, 1.0273) for respiratory admissions at lag 0-7 day over the entire study period. Despite non-homogenous decreasing trends in annual PM₁₀ concentrations during the study period, the effects of PM₁₀ on cardiovascular and respiratory admissions remained significant and even showed an increasing trend for cardiovascular admissions. Specifically, the relative risks of cardiovascular admission per 10 μg/m³ increase in PM₁₀ were 1.0050 (95% CI: 0.9965, 1.0135), 1.0086 (95% CI: 1.0000, 1.0174), and 1.0103 (95% CI: 1.0041, 1.0165) for the period of 2006-2008, 2009-2011, and 2012-2014, respectively (p-value for interaction <0.01). This finding indicated that estimated effects of PM₁₀ on cardiovascular admissions significantly changed over time, speculating that the composition of PM₁₀ might have changed and introduced the alterations of overall toxicity of PM₁₀. Therefore, the efforts on air pollution control need to be continued to reduce health effects of PM₁₀ in the future.

Acute effects of air pollution on all-cause mortality: a natural experiment from haze control measures in Chiang Mai Province, Thailand

BACKGROUND

Serious haze episodes have been a seasonal event in Chiang Mai province for more than a decade. In 2008, local government agencies introduced comprehensive measures to control haze and limit its impacts on public health. This study assessed the acute effects of ambient air pollutants on all-cause mortality before and after the introduction of those haze control measures.

METHODS

We obtained daily mortality counts and data on mass concentrations of particulate matter <10 micron in aerodynamic diameter (PM₁₀), gaseous pollutants (SO₂, NO₂, O₃, and CO), and meteorology in Chiang Mai Province between January 2002 and December 2016. We analyzed the data using a case-crossover approach adjusting for temperature, relative humidity, seasonality, and day-of-week. We assessed change in the excess risks of all-cause mortality associated with an increase in interquartile range (IQR) of pollutant concentration before and after control measures came into force.

RESULTS

We found decreased PM₁₀ levels and markedly reduced excess risks of daily mortality associated with an IQR increase in PM₁₀ concentrations in the years after haze-control measures were implemented (2009-2016). We found mixed results for gaseous pollutants: SO₂ showed no significant change in excess risk of daily mortality throughout the study period, while NO₂ and CO showed significant excess risks only in the period 2012-2016, and 8-h maximum O₃ showed a decrease in excess risk despite an increase in its atmospheric levels after the introduction of haze control measures in 2008.

CONCLUSIONS

The findings indicate that the government haze control measures first introduced in Chiang Mai province in 2008 have successfully reduced episodic PM₁₀ concentrations, which has led to a decrease in short-term all-cause mortality.

The interplay of haze characteristics on mortality in the Pearl River Delta of China

To estimate the mortality risk from haze and the modifying effects by three characteristics of haze (intensity, duration and timing), data on haze and mortality in the Pearl River Delta region from 2013 to 2016 were collected. We first estimated mortality risk during haze days compared with non-haze days. Then we classified haze into several categories by considering one or any two of the three haze characteristics together, and further calculated the mortality risks separately. The mortality risk increased 5.0% (95% confidence intervals (CI): 3.1%-6.9%) during hazy days compared with non-haze days, with larger effect for the elderly ≥ 85 years old (Excess risk (ER): 8.7%, 95% CI: 3.9%-13.6%) than other age groups. Mortality risk increased in longer haze (ER: 4.4%, 95% CI: 2.9%-6.0%) compared with shorter haze (ER: 1.9%, 95% CI: 0.7%-3.2%). The greatest effect of any two of haze characteristics was observed when haze was intense and long (ER: 4.8%, 95% CI: 3.0%-6.6%). Our study indicates that haze significantly increased mortality risk in the Pearl River Delta. The health effects of haze may be under-estimated when using a single air pollutant concentration during haze periods to assess health risk of haze events. The haze intensity, duration, and time of occurrence should be accounted for in appropriate risk assessment of haze.

Impact of Reductions in Emissions from Major Source Sectors on Fine Particulate Matter-Related Cardiovascular Mortality

BACKGROUND

Reductions in ambient concentrations of fine particulate matter (PM2.5) have contributed to reductions in cardiovascular (CV) mortality.

OBJECTIVES

We examined changes in CV mortality attributed to reductions in emissions from mobile, point, areal, and nonroad sources through changes in concentrations of PM2.5 and its major components [nitrates, sulfates, elemental carbon (EC), and organic carbon (OC)] in 2,132 U.S. counties between 1990 and 2010.

METHODS

Using Community Multiscale Air Quality model estimated PM2.5 total and component concentrations, we calculated population-weighted annual averages for each county. We estimated PM2.5 total- and component-related CV mortality, adjusted for county-level population characteristics and baseline PM2.5 concentrations. Using the index of Emission Mitigation Efficiency for primary emission-to-particle pathways, we expressed changes in particle-related mortality in terms of precursor emissions by each sector.

RESULTS

PM2.5 reductions represented 5.7% of the overall decline in CV mortality. Large point source emissions of sulfur dioxide accounted for 6.685 [95% confidence interval (CI): 5.703, 7.667] fewer sulfate-related CV deaths per 100,000 people. Mobile source emissions of primary EC and nitrous oxides accounted for 3.396 (95% CI: 2.772, 4.020) and 3.984 (95% CI: 2.472, 5.496) fewer CV deaths per 100,000 people respectively. Increased EC and OC emissions from areal sources increased carbon-related CV mortality by 0.788 (95% CI: -0.540, 2.116) and 0.245 (95% CI: -0.697, 1.187) CV deaths per 100,000 people.

DISCUSSION

In a nationwide epidemiological study of emission sector contribution to PM2.5-related mortality, we found that reductions in sulfur-dioxide emissions from large point sources and nitrates and EC emissions from mobile sources contributed the largest reduction in particle-related mortality rates respectively. https://doi.org/10.1289/EHP5692.

Spatial variation in the effects of air pollution on cardiovascular mortality in Beijing, China

Due to lack of data from multiple air quality monitoring stations, studies about spatial association between concentrations of ambient pollutants and mortality in China are rare. To investigate the spatial variation of association between concentrations of particulate matter less than 10 μm in aerodynamic diameter (PM₁₀) and nitrogen dioxide (NO₂) and cardiovascular mortality in Beijing, China, we collected data including daily deaths, concentrations of PM₁₀ and NO₂, and meteorological factors from January 1, 2009, to December 31, 2010, in all 16 districts of Beijing. Generalized additive model (GAM) and generalized additive mixed model (GAMM) were used to examine the citywide and district-specific effects of PM₁₀ and NO₂ on cardiovascular mortality. The citywide effect derived from GAMM was lower than that derived from GAM and the strongest effects were identified for 2-day moving average lag 0-1. For every 10 μg/m³ increases in concentrations of PM₁₀ and NO₂, the corresponding daily cardiovascular mortality increases in 0.31% (95%CI 0.15%, 0.46%) and 1.63% (95%CI 1.11%, 2.13%), respectively. The death risk associated with air pollutants varied across different geographic districts in Beijing. We found spatially varied adverse effects of air pollution on cardiovascular deaths in Beijing. But there was insufficient evidence to show the significant spatial heterogeneity in mortality effects of PM₁₀ and NO₂ in this study.

Temporal variations in ambient particulate matter reduction associated short-term mortality risks in Guangzhou, China: A time-series analysis (2006-2016)

Numerous studies have reported associations between ambient particulate matter (PM) and daily mortality; however, little is known about temporal variations in ambient air pollution associated mortality risks, particularly in developing countries with limited long time-series air monitoring data. In present study, we assessed the associations and temporal relationships between ambient PM and daily mortality in Guangzhou, China, during 2006-2016. With this unique 11-year dataset, we related daily concentrations of PM with aerodynamic diameter < 2.5 μm (PM_2.5), between 2.5 and 10 μm (PM_10-2.5) and <10 μm (PM₁₀) to daily mortality in Guangzhou. We applied overdispersed Poisson regression with adjustment for time trend and potential confounding factors. Multiple level sensitivity analyses were conducted to examine the robustness of main results. Between 2006 and 2016, annual concentrations of PM_2.5 decreased by 50.8% to 27.0 μg/m³, of PM_10-2.5 by 27.6% to 16.2 μg/m³, and of PM₁₀ by 44.1% to 43.3 μg/m³ in Guangzhou. In this study, per 10 μg/m³ increases in mean concentrations at current day and 6 prior days of death (lag06), we observed increases in total mortality risks of 0.55% (95% Confidence Interval (CI): 0.24%, 0.86%) for PM_2.5, 0.99% (95%CI: 0.48%, 1.50%) for PM_10-2.5, and 0.44% (95%CI: 0.22%, 0.65%) for PM₁₀. Stronger associations were observed for ambient PM on cardio-respiratory mortality and people at age ≥ 65 years. Despite drastic reductions in annual PM levels, PM_2.5 associated cardiovascular and respiratory mortality risks remained significant at 1.26% (95%CI: 0.19%, 2.35%) and 1.91% (95%CI: 0.25%, 3.60%) during 2014-2016. Further, PM_2.5 and PM₁₀ associated respiratory mortality risks showed increasing trend over time (p-value = 0.03 for PM_2.5). In summary, though ambient PM levels decreased substantially in Guangzhou in recent years, PM_2.5 and PM₁₀ associated cardio-respiratory mortality risks remained significant and respiratory mortality risks even increased. Our findings provide strong rationale for continuation of ambient air pollution control effort for public health protection in the future.

Temporal variability of short term effects of PM10 on mortality in Seoul, Korea

Health effects of PM₁₀ on mortality have been studies worldwide. However, not many studies have questioned possibility that short-term effects of PM₁₀ can be changed over time. Identifying temporal variability of the effects would be of help to getting more valid PM₁₀ effect estimates which are a major basis for public health policies. In this study, temporal variability of short-term effects of PM₁₀ for mortality was investigated from 2001 to 2015 in Seoul, Korea. A time series analysis was used to estimate the effects of PM₁₀ on all-cause, circulatory, and respiratory mortality. Study period was divided into five years of moving time window, and relative risks and its 95% confidence intervals were estimated using distributed lag model for each time window. The annual average of PM₁₀ in Seoul decreased from 52.6 μg/m³ in 2001 to 40.5 μg/m³ in 2015. There were significant temporal trends in PM₁₀ effects regarding each mortality. The effects of PM₁₀ tend to slightly increase in early of the study period and then dropped in recent years. An increase of 2 days of cumulative exposure of PM₁₀ was associated with 0.31% (95% confidence interval: 0.15, 0.46) increase in all-cause mortality for 2001-2005 period, 0.61% (95% confidence interval: 0.34, 0.89) increase in 2005-2009 period, and -0.06% (95% confidence interval: -0.38, 0.25) increase in 2011-2015 period. We found evidence that short-term effects of PM₁₀ on mortality have been changed over time in Seoul, Korea. The observed temporal trend might attributable from two factors which are change of PM₁₀ compositions and population vulnerability. If effects of PM₁₀ vary over time, considering its change would be necessary not only in the estimation of the PM₁₀ effect but also its application for a variety of public health policies.

Two-way effect modifications of air pollution and air temperature on total natural and cardiovascular mortality in eight European urban areas

BACKGROUND

Although epidemiological studies have reported associations between mortality and both ambient air pollution and air temperature, it remains uncertain whether the mortality effects of air pollution are modified by temperature and vice versa. Moreover, little is known on the interactions between ultrafine particles (diameter ≤ 100 nm, UFP) and temperature.

OBJECTIVE

We investigated whether the short-term associations of particle number concentration (PNC in the ultrafine range (≤100 nm) or total PNC ≤ 3000 nm, as a proxy for UFP), particulate matter ≤ 2.5 μm (PM_2.5) and ≤ 10 μm (PM₁₀), and ozone with daily total natural and cardiovascular mortality were modified by air temperature and whether air pollution levels affected the temperature-mortality associations in eight European urban areas during 1999-2013.

METHODS

We first analyzed air temperature-stratified associations between air pollution and total natural (nonaccidental) and cardiovascular mortality as well as air pollution-stratified temperature-mortality associations using city-specific over-dispersed Poisson additive models with a distributed lag nonlinear temperature term in each city. All models were adjusted for long-term and seasonal trend, day of the week, influenza epidemics, and population dynamics due to summer vacation and holidays. City-specific effect estimates were then pooled using random-effects meta-analysis.

RESULTS

Pooled associations between air pollutants and total and cardiovascular mortality were overall positive and generally stronger at high relatively compared to low air temperatures. For example, on days with high air temperatures (>75th percentile), an increase of 10,000 particles/cm³ in PNC corresponded to a 2.51% (95% CI: 0.39%, 4.67%) increase in cardiovascular mortality, which was significantly higher than that on days with low air temperatures (<25th percentile) [-0.18% (95% CI: -0.97%, 0.62%)]. On days with high air pollution (>50th percentile), both heat- and cold-related mortality risks increased.

CONCLUSION

Our findings showed that high temperature could modify the effects of air pollution on daily mortality and high air pollution might enhance the air temperature effects.

The spatial variation in the effects of air pollution on cardiovascular mortality in Beijing, China

Owing to lack of data from multiple air quality monitoring stations, studies about spatial association between concentrations of ambient pollutants and mortality in China are rare. To investigate the spatial variation of association between concentrations of particulate matter less than 10 μm in aerodynamic diameter (PM₁₀), nitrogen dioxide (NO₂) and carbon monoxide (CO) and cardiovascular mortality in Beijing, China, we collected data including daily deaths, concentrations of PM₁₀, NO₂ and CO, and meteorological factors from 1 January 2009 to 31 December 2010 in all 16 districts of Beijing. Generalized additive model (GAM) and generalized additive mixed model (GAMM) were used to examine the citywide and district-specific effects of PM₁₀, NO₂ and CO on cardiovascular mortality. The citywide effect derived from GAMM was lower than that derived from GAM, and the strongest effects were identified for 2-day moving average lag 0-1. The interquartile increases in concentrations of PM₁₀, NO₂ and CO were associated with 2.46 (95% confidence interval (CI), 1.22-3.72), 4.11 (95%CI, 2.82-5.42) and 2.23 (95%CI, 1.14-3.33) percentage increases in daily cardiovascular mortality by GAMM, respectively. The relative risk of each district compared with reference district was generally statistically significant. The death risk associated with air pollutants varies across different geographic districts in Beijing. The data indicate that the risk is high in suburban areas and rural counties. We found significant and spatially varied adverse effects of air pollution on cardiovascular deaths across the rural and urban areas in Beijing.

Has the risk of mortality related to short-term exposure to particles changed over the past years in Athens, Greece?

Although the health effects of short-term exposure to ambient particles have been well documented, there is a need to update scientific knowledge due to the continuously changing profile of the air pollution mixture. Furthermore the effect of the severe economic crisis in Greece that started in 2008 on previously reported associations has not been studied. We assessed the change in mortality risk associated with short-term exposure to PM₁₀ in Athens, Greece during 2001-12. Time-series data on the daily concentrations of regulated particles and all cause, cardiovascular and respiratory mortality were analyzed using overdispersed Poisson regression models, controlling for time-varying confounders such as seasonality, meteorology, influenza outbreaks, summer holidays and day of the week. We assessed changes in risk over time by inclusion of an interaction term between particles' levels and time or predefined periods, i.e. 2001-07 and 2008-12. While the related mortality risks increased over the analyzed period, the difference before and after 2008 was significant only for total mortality (p-value for interaction .03) and driven by the difference observed among those ≥75 years. An interquartile increase in PM₁₀ before 2008 was associated with 1.51% increase in deaths among ≥75 years (95% Confidence interval (CI): 0.62%, 2.40%), while after 2008 with a 2.61% increase (95%CI: 1.72%, 3.51%) (p-value for interaction .01). Our results indicate that despite the decline in particles' concentration in Athens, Greece during 2001-12 the associated mortality risk has possibly increased, suggesting that the economic crisis initiated in 2008 may have led to changes in the particles' composition due to the ageing of the vehicular fleet and the increase in the use of biomass fuel for heating.

Ultrafine and Fine Particle Number and Surface Area Concentrations and Daily Cause-Specific Mortality in the Ruhr Area, Germany, 2009-2014

BACKGROUND

Although epidemiologic studies have shown associations between particle mass and daily mortality, evidence on other particle metrics is weak.

OBJECTIVES

We investigated associations of size-specific particle number concentration (PNC) and lung-deposited particle surface area concentration (PSC) with cause-specific daily mortality in contrast to PM₁₀.

METHODS

We used time-series data (March 2009-December 2014) on daily natural, cardiovascular, and respiratory mortality (NM, CVM, RM) of three adjacent cities in the Ruhr Area, Germany. Size-specific PNC (electric mobility diameter of 13.3-750 nm), PSC, and PM₁₀ were measured at an urban background monitoring site. In single- and multipollutant Poisson regression models, we estimated percentage change (95% confidence interval) [% (95% CI)] in mortality per interquartile range (IQR) in exposure at single-day (0-7) and aggregated lags (0-1, 2-3, 4-7), accounting for time trend, temperature, humidity, day of week, holidays, period of seasonal population decrease, and influenza.

RESULTS

PNC_100-750 and PSC were highly correlated and had similar immediate (lag0-1) and delayed (lag4-7) associations with NM and CVM, for example, 1.12% (95% CI: 0.09, 2.33) and 1.56% (95% CI: 0.22, 2.92) higher NM with IQR increases in PNC_100-750 at lag0-1 and lag4-7, respectfully, which were slightly stronger then associations with IQR increases in PM₁₀. Positive associations between PNC and NM were strongest for accumulation mode particles (PNC 100-500 nm), and for larger UFPs (PNC 50-100 nm). Associations between NM and PNC_<100 changed little after adjustment for O₃ or PM₁₀, but were more sensitive to adjustment for NO₂.

CONCLUSION

Size-specific PNC (50-500 nm) and lung-deposited PSC were associated with natural and cardiovascular mortality in the Ruhr Area. Although associations were similar to those estimated for an IQR increase in PM₁₀, particle number size distributions can be linked to emission sources, and thus may be more informative for potential public health interventions. Moreover, PSC could be used as an alternative metric that integrates particle size distribution as well as deposition efficiency. https://doi.org/10.1289/EHP2054.

Fine particulate matters: The impact of air quality standards on cardiovascular mortality

BACKGROUND

In 1997 the U.S. Environmental Protection Agency set the first annual National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM2.5). Although the weight of scientific evidence has determined that a causal relationship exists between PM2.5 exposures and cardiovascular effects, few studies have concluded whether NAAQS-related reductions in PM2.5 led to improvements in public health.

METHODS

We examined the change in cardiovascular (CV) mortality rate and the association between change in PM2.5 and change in CV-mortality rate before (2000-2004) and after implementation of the 1997 annual PM2.5 NAAQS (2005-2010) among U.S. counties. We further examined how the association varied with respect to two factors related to NAAQS compliance: attainment status and design values (DV). We used difference-in-differences and linear regression models, adjusted for sociodemographic confounders.

FINDINGS

Across 619 counties, there were 1.10 (95% CI: 0.37, 1.82) fewer CV-deaths per year per 100,000 people for each 1µg/m3 decrease in PM2.5. Nonattainment counties had a twofold larger reduction in mean annual PM2.5, 2.1µg/m3, compared to attainment counties, 0.97µg/m3. CV-mortality rate decreased by 0.59 (95% CI: -0.54, 1.71) in nonattainment and 1.96 (95% CI: 0.77, 3.15) deaths per 100,000 people for each 1µg/m3 decrease in PM2.5 in attainment counties. When stratifying counties by DV, results were similar: counties with DV greater than 15µg/m3 experienced the greatest decrease in mean annual PM2.5 (2.29µg/m3) but the smallest decrease in CV-mortality rate per unit decrease in PM2.5, 0.73 (95% CI: -0.57, 2.02).

INTERPRETATION

We report a significant association between the change in PM2.5 and the change in CV-mortality rate before and after the implementation of NAAQS and note that the health benefits per 1µg/m3 decrease in PM2.5 persist at levels below the current national standard.

FUNDING

US EPA intermural research.

Associations between mortality and prolonged exposure to elevated particulate matter concentrations in East Asia

Previous epidemiological studies regarding mortality and particulate matter with an aerodynamic diameter of <10μm (PM₁₀) have considered only absolute concentrations of PM₁₀ as a risk factor. However, none have evaluated the durational effect of multi-day periods with high PM₁₀ concentrations. To evaluate the durational effect (i.e., number of days) of high PM₁₀ concentrations on mortality, we collected data regarding 3,662,749 deaths from 28 cities in Japan, South Korea, and China (1993-2009). Exposure was defined as consecutive days with daily PM₁₀ concentrations ≥75μg/m³. A Poisson model was used with duration as the variable of interest, while controlling for daily PM₁₀ concentrations, meteorological variables, seasonal trends, and day of the week. The increase in mortality risk for each additional consecutive day with PM₁₀ concentrations ≥75μg/m³ was 0.68% in Japan (95% confidence interval [CI]: 0.35-1.01%), 0.48% in South Korea (95% CI: 0.30-0.66%), and 0.24% in China (95% CI: 0.14-0.33%). The annual average maximum number of consecutive days with high PM₁₀ in Japan (2.40days), South Korea (6.96days), and China (42.26days) was associated with non-accidental death increases of 1.64% (95% CI: 1.31-1.98%), 3.37% (95% CI: 3.19-3.56%), and 10.43% (95% CI: 10.33-10.54%), respectively. These findings may facilitate the planning of public health interventions to minimize the health burden of air pollution.

Effects of NO2 exposure on daily mortality in São Paulo, Brazil

BACKGROUND

Recent reports have suggested that air pollution mixtures represented by nitrogen dioxide (NO₂) may have effects on human health, which are independent from those of particulate matter mass. We evaluate the association between NO₂ and daily mortality among elderly using one- and multipollutant models.

METHODS

This study was a daily time series of non-accidental and cause-specific mortality among the elderly living in São Paulo, Brazil, between 2000 and 2011. Effects of NO₂, particulate matter smaller than 10µm (PM10), carbon monoxide (CO) and ozone (O₃) were estimated in Poisson generalized additive models. The single lag effect at lags 0 and 1 days and the cumulative effect from 0 to lag 10 days were evaluated in one-, two-, three- and four-pollutant models. The cumulative risk index (CRI) recently proposed to analyze associations with health of multiple correlated pollutants was additionally estimated for each multipollutant model.

RESULTS

An association between NO₂, PM10, CO and O₃ exposures and non-accidental and cause-specific deaths was found in one-pollutant models. NO₂ effects remained significant in multipollutant models for non-accidental and circulatory deaths. The estimated CRIs suggested that circulatory deaths were mainly associated with NO₂, and respiratory deaths mainly with CO and O₃, regardless the lag. For non-accidental deaths, multipollutant models were associated with the highest CRI, with the main pollutants depending on the chosen lag.

CONCLUSIONS

The results suggest that air pollution mixtures represented by NO₂ have an effect on non-accidental and circulatory mortality, which is independent from PM10, CO and O₃. The CRI was always larger than the risks associated with single pollutants.

Analysis of Temporal Variability in the Short-term Effects of Ambient Air Pollutants on Nonaccidental Mortality in Rome, Italy (1998-2014)

OBJECTIVES

The association between short-term air pollution exposure and daily mortality has been widely investigated, but little is known about the temporal variability of the effect estimates. We examined the temporal relationship between exposure to particulate matter (PM) (PM₁₀, PM_2.5) and gases (NO₂, SO₂, and CO) with mortality in a large metropolitan area over the last 17 y.

METHODS

Our analysis included 359,447 nonaccidental deaths among ≥35-y-old individuals in Rome, Italy, over the study period 1998–2014. We related daily concentrations to mortality counts with a time-series Poisson regression analysis adjusted for long-term trends, meteorology, and population dynamics.

RESULTS

Annual average concentrations decreased over the study period for all pollutants (e.g., from 42.9 to 26.6 μg/m³ for PM₁₀). Each pollutant was positively associated with mortality, with estimated percentage increases over the entire study period ranging from 0.19% (95% CI: 0.13, 0.26) for a 1-Mg/m³ increase in CO (0–1 d lag) to 3.03% (95% CI: 2.44, 3.63) for a 10-μg/m³ increase in NO₂ (0–5 d lag). We did not observe clear temporal patterns in year- or period-specific effect estimates for any pollutant. For example, we estimated that a 10-μg/m³ increase in PM₁₀ was associated with 1.16% (95% CI: 0.53, 1.79), 0.99% (95% CI: 0.23, 1.77), and 1.87% (95% CI: 1.00, 2.74) increases in mortality for the periods 2001–2005, 2006–2010, and 2011–2014, respectively, and corresponding estimates for a 10-μg/m³ increase in NO₂ were 4.20% (95% CI: 3.15, 5.25), 1.78% (95% CI: 0.73, 2.85), and 3.32% (95% CI: 2.03, 4.63).

CONCLUSIONS

Mean concentrations of air pollutants have decreased over the last two decades in Rome, but effect estimates for a fixed increment in each exposure were generally consistent. These findings suggest that there has been little or no change in the overall toxicity of the air pollution mixture over time. https://doi.org/10.1289/EHP19.

Associations between ultrafine and fine particles and mortality in five central European cities - Results from the UFIREG study

BACKGROUND

Evidence on health effects of ultrafine particles (UFP) is still limited as they are usually not monitored routinely. The few epidemiological studies on UFP and (cause-specific) mortality so far have reported inconsistent results.

OBJECTIVES

The main objective of the UFIREG project was to investigate the short-term associations between UFP and fine particulate matter (PM)<2.5μm (PM2.5) and daily (cause-specific) mortality in five European Cities. We also examined the effects of PM<10μm (PM10) and coarse particles (PM2.5-10).

METHODS

UFP (20-100nm), PM and meteorological data were measured in Dresden and Augsburg (Germany), Prague (Czech Republic), Ljubljana (Slovenia) and Chernivtsi (Ukraine). Daily counts of natural and cardio-respiratory mortality were collected for all five cities. Depending on data availability, the following study periods were chosen: Augsburg and Dresden 2011-2012, Ljubljana and Prague 2012-2013, Chernivtsi 2013-March 2014. The associations between air pollutants and health outcomes were assessed using confounder-adjusted Poisson regression models examining single (lag 0-lag 5) and cumulative lags (lag 0-1, lag 2-5, and lag 0-5). City-specific estimates were pooled using meta-analyses methods.

RESULTS

Results indicated a delayed and prolonged association between UFP and respiratory mortality (9.9% [95%-confidence interval: -6.3%; 28.8%] increase in association with a 6-day average increase of 2750particles/cm(3) (average interquartile range across all cities)). Cardiovascular mortality increased by 3.0% [-2.7%; 9.1%] and 4.1% [0.4%; 8.0%] in association with a 12.4μg/m(3) and 4.7μg/m(3) increase in the PM2.5- and PM2.5-10-averages of lag 2-5.

CONCLUSIONS

We observed positive but not statistically significant associations between prolonged exposures to UFP and respiratory mortality, which were independent of particle mass exposures. Further multi-centre studies are needed investigating several years to produce more precise estimates on health effects of UFP.

Assessing responses of cardiovascular mortality to particulate matter air pollution for pre-, during- and post-2008 Olympics periods

BACKGROUND

The link between particulate air pollution and cardiovascular (CVD) mortality has been investigated. However, there is little direct evidence that reduction measures which decrease particulate air pollution would lead to a reduction in CVD mortality.

OBJECTIVES

In Beijing, China, air quality improvement strategies were developed and actions were taken before and during the 2008 Olympic and Paralympic Games. Taking advantage of this opportunity, the aim of the study was to assess the effects of changes in particulate air pollution before (May 20-July 20, 2008), during (August 1-September 20, 2008) and after (October 1-December 1, 2008) the Olympics period.

METHODS

Concentrations of air pollution, meteorology and CVD death counts were obtained from official networks and monitoring sites located on the Peking University campus. Air pollution effects with lags of 0-4 days as well as of the 5-day average on cause-specific CVD mortality were investigated for the complete study period (May 20-December 1, 2008) using Quasi-Poisson regression models. Different gender and age subgroups were taken into account. Additionally, effect modification by air mass origin was investigated. In a second step, air pollution effects were estimated for the three specific periods by including an interaction term in the models.

RESULTS

We observed large concentration decreases in all measured air pollutants during the unique pollution intervention for the Beijing 2008 Olympics. For the whole period, adverse effects of particulate air pollution were observed on CVD mortality with a 1-day delay as well as for the 5-day average exposure, e.g. an 8.8% (95%CI: 2.7-15.2%) increase in CVD mortality with an interquartile range increase in ultrafine particles. The effects were more pronounced in females, the elderly and for cerebrovascular deaths, but not modified by air mass origin. The specific sub-period analysis results suggested that the risks of CVD mortality were lowest during the Olympic Games where strongest reduction measures have been applied.

CONCLUSIONS

The results indicated that the reduction of air pollution due to air quality control measures led to a decreased risk of CVD mortality in Beijing. Our findings provide new insight into efforts to reduce ambient air pollution.

Effects of ambient air particles on mortality in Seoul: Have the effects changed over time?

BACKGROUND

Several studies have shown that there may be temporal variation in PM short-term effect on mortality. This temporal pattern may play an important role in evaluating air quality policies.

OBJECTIVES

We investigated temporal variation in the association between PM and mortality in Seoul, Korea, 1998-2011.

METHODS

We adopted a generalized additive model and a series of time windows of five years to analyze temporal variation in associations between PM and all-cause, cardiovascular, and respiratory mortality. This time-window approach offers not only a comparison between one and the other half period but also successive variation. Time-varying associations were estimated only for days without Asian dust (dust storm blown from the Gobi desert) intrusion.

RESULTS

Annual average PM10 and PM2.5 total mass decreased from 70.0 to 46.9 µg/m(3) and 44.4 to 23.4 µg/m(3), respectively, during 2001-2011. A 10 µg/m(3) increase in PM10 was associated with 0.16% (95% CI=-0.03% to 0.35%) additional all-cause deaths in 2002-2006 and it increased to 0.26% (95% CI=0.05-0.48%) in 2007-2011. For PM2.5, the association increased from 0.35% (95% CI=-0.02% to 0.71%) to 0.48% (95% CI=0.08-0.88%). For cardiovascular and respiratory mortality, increasing trends with stronger estimates were found.

CONCLUSIONS

The present study showed temporally increasing trends in associations between PM and mortality. Current policies may not be as effective to reducing health risks attributable to PM as expected. Air quality interventions should be encouraged in terms of causal factors for time-varying association between PM and mortality.

Short-term effects of air temperature on mortality and effect modification by air pollution in three cities of Bavaria, Germany: a time-series analysis

BACKGROUND

Air temperature has been shown to be associated with mortality; however, only very few studies have been conducted in Germany. This study examined the association between daily air temperature and cause-specific mortality in Bavaria, Southern Germany. Moreover, we investigated effect modification by age and ambient air pollution.

METHODS

We obtained data from Munich, Nuremberg as well as Augsburg, Germany, for the period 1990 to 2006. Data included daily cause-specific death counts, mean daily meteorology and air pollution concentrations (particulate matter with a diameter<10 μm [PM10] and maximum 8-h ozone). We used Poisson regression models combined with distributed lag non-linear models adjusting for long-term trend, calendar effects, and meteorological factors. Air pollutant concentrations were categorized into three levels, and an interaction term was included to quantify potential effect modification of the air temperature effects.

RESULTS

The temperature-mortality relationships were non-linear for all cause-specific mortality categories showing U- or J-shaped curves. An increase from the 90th (20.0 °C) to the 99th percentile (24.8 °C) of 2-day average temperature led to an increase in non-accidental mortality by 11.4% (95% CI: 7.6%-15.3%), whereas a decrease from the 10th (-1.0 °C) to the 1st percentile (-7.5 °C) in the 15-day average temperature resulted in an increase of 6.2% (95% CI: 1.8%-10.8%). The very old were found to be most susceptible to heat effects. Results also suggested some effect modification by ozone, but not for PM10.

CONCLUSIONS

Results indicate that both very low and very high air temperature increase cause-specific mortality in Bavaria. Results also pointed to the importance of considering effect modification by age and ozone in assessing temperature effects on mortality.

Health risks caused by short term exposure to ultrafine particles generated by residential wood combustion: a case study of Temuco, Chile

Temuco is one of the most highly wood smoke polluted cities in Chile; however, there is scarce evidence of respiratory morbidity due to fine particulate matter. We aimed to estimate the relationship between daily concentration of ultrafine particles (UFP), with an aerodynamic diameter ≤ 0.1 μm, and outpatient visits for respiratory illness at medical care centers of Temuco, Chile, from August the 20th, 2009 to June the 30th, 2011. The Air Pollution Health Effects European Approach (APHEA2) protocol was followed, and a multivariate semi-parametric Poisson regression model was fitted with GAM techniques using R-Project statistical package; controlling for trend, seasonality, and confounders. The daily UFP were measured by a MOUDI NR-110 sampler. We found that results of the statistical analyses show significant associations between UFP and respiratory outpatient visits, with the elderly (population ≥ 65 years), being the group that presented the greatest risk. An interquartile increase of 4.73 μg/m(3) in UFP (lag 5 days) was associated with respiratory outpatient visits with a relative risk (RR) of 1.1458 [95% CI (1.0497-1.2507)] for the elderly. These results show novel findings regarding the relevance of daily UFP concentrations and health risk, especially for susceptible population in a wood smoke polluted city.

Exposure and health impacts of outdoor particulate matter in two urban and industrialized area of Tabriz, Iran

Numerous studies have shown associations between air pollution and health effects on human. The aims of the present study were to provide quantitative data on variation of atmospheric particulate matter (PM) concentration and the impact of PM on the health of people living in Tabriz city. The approach proposed by the World Health Organization (WHO) was applied using the AirQ 2.2.3 software developed by the WHO European Centre for Environment and Health, Bilthoven Division. The concentration of particulate matter were measured at urban and industrial suburban sites in Tabriz, Iran, from September 2012 to June 2013. TSP and PM₁₀ samples were collected using high volume samplers. PM_2.5 and PM₁ were measured by Haz-Dust EPAM-5000 particulate air monitors. The annual average concentrations of TSP, PM₁₀, PM_2.5, and PM₁ in the urban site were 142.2 ± 76.3, 85.3 ± 43.9, 39 ± 19.1, and 28.4 ± 14.9 μg/m³ (mean ± SD), respectively. Also in industrial suburban, the total average concentrations of TSP, PM₁₀, PM_2.5, and PM₁ were measured as 178.7 ± 52.7, 109.9 ± 30.2, 40.0 ± 10.9, and 31.4 ± 9.1 μg/m³, respectively. The PM₁₀/TSP ratio for the whole study period ranged between 0.35-0.91 and 0.32-0.79 in the urban and suburban sites, respectively. Total mortalities associated with TSP, PM₁₀ and PM_2.5 concentrations were 327, 363, and 360, respectively. Furthermore, the cardiovascular mortalities for TSP and PM₁₀ were 202 and 227 individual, respectively. According to the attributable respiratory mortalities of 99 and 67 associated respectively with TSP and PM₁₀, it is clear that cardiovascular mortality resulted from PM might attributed to total mortality. The maximum 24-hour concentration of PM was observed during winter followed by autumn and the lowest one was during spring.

Short-term effects of PM2.5, PM10 and PM2.5-10 on daily mortality in The Netherlands

INTRODUCTION

Information on the relationship between levels of particulate matter (PM) smaller than 2.5 μm and mortality rates in Europe is relatively sparse because of limited availability of PM2.5 measurement data. Even less information is available on the health effects attributable to PM2.5-10, especially for North-West Europe.

OBJECTIVES

To investigate the relationship between various PM size fractions and daily mortality rates.

METHODS

Daily concentrations of PM from the Dutch National Ambient Air Quality Monitoring Network as well as all cause and cause-specific mortality rates in The Netherlands were obtained for the period 2008-2009. Poisson regression analysis using generalized additive models was used, with adjustment for potential confounding including long-term and seasonal trends, influenza incidence, meteorological variables, day of the week, and holidays. Different measures of PM (PM2.5, PM10 and PM2.5-10) were analysed.

RESULTS

PM10 and PM2.5 levels were statistically significantly (p<0.05) associated with all cause and cause-specific deaths. For example, a 10 μg/m(3) increase in previous day PM was associated with 0.8% (95% CI 0.3-1.2) excess risk in all cause mortality for PM2.5 and a 0.6% (CI 0.2-1.0) excess risk for PM10. No appreciable associations were observed for PM2.5-10. Effects of PM10, and PM2.5 were insensitive to adjustment for PM2.5-10, and vice-versa. PM10 and PM2.5 were too highly correlated to disentangle their independent effects.

CONCLUSIONS

PM10 and PM2.5 both were significantly associated with all cause and cause-specific mortality. We were unable to demonstrate significant effects for PM2.5-10, possibly due to the lower temporal variability and the higher exposure misclassification in PM2.5-10 compared to PM10 or PM2.5. The lack of effects of PM2.5-10 in our study should therefore not be interpreted as an indication that PM2.5-10 can be considered harmless.

The spatial characteristics of ambient particulate matter and daily mortality in the urban area of Beijing, China

Few epidemiological studies have reported the spatial characteristics of the association between particulate matter <10μm in aerodynamic diameter (PM(10)) and mortality in China. This study explored the spatial characteristics of the association between ambient PM(10) and mortality in the urban area of Beijing, China. We collected daily data on air pollution, weather conditions and mortality in the eight urban districts of Beijing from Jan. 1st 2008 to Dec. 31st 2009. A Poisson Generalized Additive Model (GAM) was used to examine the district-specific effects of PM(10) on cause-specific mortality. A Poisson Generalized Additive Mixed Model (GAMM) was used to examine the urban-wide association between PM(10) and cause-specific mortality while controlling for the random effects of districts, compared with GAM which did not control for the random effects of districts. The inter-quartile ranges (IQRs) of annual PM(10) ranged from 83.5 μg/m(3) (Chaoyang district) to 96.0 μg/m(3) (Shijingshan district). A 96.0 μg/m(3) increase of PM(10) was associated with a 7.52% (95%CI: 1.78%-13.56%) increase of cardiovascular mortality in Shijingshan district while an 87.0 μg/m(3) increase of PM(10) was associated with a 7.68% (95%CI: 0.08%-15.86%) increase of respiratory deaths in Dongcheng district. The urban-wide effects derived from GAMM showed that an 88.0 μg/m(3) increase of PM(10) was associated with an increase of 1.30% (95%CI: 0.45%-2.16%), 2.60% (95%CI: 0.14%-5.11%) in non-accidental and respiratory mortality, illustrating, higher results than those from the GAM. In conclusion, there is spatial variation in ambient PM(10) concentration as well as in the effects of PM(10) on cause-specific mortality in the urban area of Beijing. Additionally, GAMM model may be more effective in estimating the spatial association between urban-wide PM(10) and cause-specific mortality.

Diesel vehicle emission and death rates in Tokyo, Japan: a natural experiment

Evidence linking air pollution with adverse cardiopulmonary outcomes is accumulating. However, few studies have been conducted to evaluate whether vehicle emission control improves public health. We thus evaluated the effect of a diesel emission control law on mortality rates in 23 wards of Tokyo metropolitan area, Japan. We obtained daily counts of mortality and concentrations of nitrogen dioxide (NO(2)) and particulate matter less than 2.5 μm in diameter (PM(2.5)) from April 2003 to December 2008. Time-series and interrupted time-series analysis were employed to analyze the data in two periods: prior to the introduction of tighter restrictions (April 2003 to March 2006) and after the enforcement (April 2006 to December 2008). Concentrations of air pollutants gradually decreased during the study period: from 36.3 ppb (NO(2)) and 22.8 μg/m(3) (PM(2.5)) to 32.1 ppb and 20.3 μg/m(3), respectively. Air pollutants were positively associated with circulatory and pulmonary disease mortality, especially cerebrovascular disease. Each same-day PM(2.5) increase of 10 μg/m(3) was associated with a 1.3% increase in cerebrovascular mortality rate (95% confidence interval: 0.2-2.4). Rate ratios were attenuated after the enforcement in most of the outcomes, probably due to reduced toxicity of the pollutants. In the crude interrupted time-series analysis, reductions of standardized mortality rates after the enforcement were the greatest in high traffic areas. Even after adjustment of longer-time trend, mortality rate from cerebrovascular disease was reduced by 8.50% (p<.001) with dose-response relationship. However, the declines in other cause-specific mortality became equivocal. This natural experiment in Tokyo suggests that emission controls improved air quality. Although suggestive, further data are needed to conclusively demonstrate an impact on mortality rates.

What are distributed lag models of particulate matter air pollution estimating when there are populations of frail individuals?

The three-state (healthy, frail, and dead) population model is commonly used in time-series investigations of mortality displacement and particulate matter air pollution (PM). In this paper, the author proposes a new population model, called the mixture population model, that by allowing PM to have differential effects on individuals in the population, extends the population models currently used in investigations of mortality displacement. Using this new model, the properties of distributed lag models (DLM) of PM are investigated. In particular, the author derives a relationship between the parameters of the proposed population model and the estimates obtained from a DLM fitted to mortality arising from the model. This relationship provides insight into the interrelationships between the size of the frail population, the number of lags of PM included in a DLM and the proportion of the effect of PM on the healthy population that is estimable. The relationship will guide and contextualize future investigations by providing researchers with the knowledge to assess the consequences of the number of lags of PM included in a DLM in terms of what they can plausibly infer about the effect of PM on mortality based on this choice of lag.

Including viral infection data supports an association between particulate pollution and respiratory admissions

OBJECTIVE

To refine and revise previous air pollution, climate and health time series analysis in Christchurch, New Zealand, introducing viral identification data (positive identification count and outbreak, defined as two of more positive tests).

METHOD

The effects on daily respiratory admissions for five years (1998-2002) of air pollution (PM(10) ), climate and virology (incorporating actual counts and outbreaks of influenza A and B (INF), para influenza virus type 3 (PIV) and respiratory syncytial virus (RSV) were examined using generalised additive models (GAMs), which are one of semiparametric models. Results were also compared with a model that included climate and air pollution parameters but without the inclusion of virology data. The data were analysed aggregately and then stratified by age group and season.

RESULTS

Different virology data detected various association levels. The highest estimates were a 3.93% (CI: 2.69-5.17) and a 3.88% (CI: 2.65-5.12) rise in respiratory admissions for a rise of 10 µg/m(3) annual PM(10) with outbreak and actual counts of PIV respectively for 0-19 years old with a three-day lag.

CONCLUSION

Refining a statistical model with the addition of virology data gives a similar estimation of the association between PM(10) levels and respiratory admissions to previous research. Use of the indicator of an outbreak of viral infection appears to be similar to actual count of viruses detected.

Bootstrap-after-bootstrap model averaging for reducing model uncertainty in model selection for air pollution mortality studies

BACKGROUND

Concerns have been raised about findings of associations between particulate matter (PM) air pollution and mortality that have been based on a single "best" model arising from a model selection procedure, because such a strategy may ignore model uncertainty inherently involved in searching through a set of candidate models to find the best model. Model averaging has been proposed as a method of allowing for model uncertainty in this context.

OBJECTIVES

To propose an extension (double BOOT) to a previously described bootstrap model-averaging procedure (BOOT) for use in time series studies of the association between PM and mortality. We compared double BOOT and BOOT with Bayesian model averaging (BMA) and a standard method of model selection [standard Akaike's information criterion (AIC)].

METHOD

Actual time series data from the United States are used to conduct a simulation study to compare and contrast the performance of double BOOT, BOOT, BMA, and standard AIC.

RESULTS

Double BOOT produced estimates of the effect of PM on mortality that have had smaller root mean squared error than did those produced by BOOT, BMA, and standard AIC. This performance boost resulted from estimates produced by double BOOT having smaller variance than those produced by BOOT and BMA.

CONCLUSIONS

Double BOOT is a viable alternative to BOOT and BMA for producing estimates of the mortality effect of PM.

Toxic effects of brake wear particles on epithelial lung cells in vitro

BACKGROUND

Fine particulate matter originating from traffic correlates with increased morbidity and mortality. An important source of traffic particles is brake wear of cars which contributes up to 20% of the total traffic emissions. The aim of this study was to evaluate potential toxicological effects of human epithelial lung cells exposed to freshly generated brake wear particles.

RESULTS

An exposure box was mounted around a car's braking system. Lung cells cultured at the air-liquid interface were then exposed to particles emitted from two typical braking behaviours ("full stop" and "normal deceleration"). The particle size distribution as well as the brake emission components like metals and carbons was measured on-line, and the particles deposited on grids for transmission electron microscopy were counted. The tight junction arrangement was observed by laser scanning microscopy. Cellular responses were assessed by measurement of lactate dehydrogenase (cytotoxicity), by investigating the production of reactive oxidative species and the release of the pro-inflammatory mediator interleukin-8. The tight junction protein occludin density decreased significantly (p < 0.05) with increasing concentrations of metals on the particles (iron, copper and manganese, which were all strongly correlated with each other). Occludin was also negatively correlated with the intensity of reactive oxidative species. The concentrations of interleukin-8 were significantly correlated with increasing organic carbon concentrations. No correlation was observed between occludin and interleukin-8, nor between reactive oxidative species and interleukin-8.

CONCLUSION

These findings suggest that the metals on brake wear particles damage tight junctions with a mechanism involving oxidative stress. Brake wear particles also increase pro-inflammatory responses. However, this might be due to another mechanism than via oxidative stress.

A review of the urban development and transport impacts on public health with particular reference to Australia: trans-disciplinary research teams and some research gaps

Urbanization and transport have a direct effect on public health. A transdisciplinary approach is proposed and illustrated to tackle the general problem of these environmental stressors and public health. Processes driving urban development and environmental stressors are identified. Urbanization, transport and public health literature is reviewed and environmental stressors are classified into their impacts and which group is affected, the geographical scale and potential inventions. Climate change and health impacts are identified as a research theme. From an Australian perspective, further areas for research are identified.