Studies on the health effects of long-term ozone exposure remain limited with mixed results. One potential source of this inconsistency is the difference in exposure time metrics. This study aimed to investigate the association between long-term exposure to ambient ozone and mortality in South Korea, using different exposure metrics. We also examined whether heterogeneity between previous studies was due to the different exposure metrics. The study population comprised 179,806 participants from the National Health Insurance Service-National Sample Cohort (2002–2015) residing in seven major cities in South Korea. Several ozone exposure metrics (year-round 24-h, year-round 8-h, warm-season 24-h, and warm-season 8-h) were calculated. Time-varying Cox proportional hazards models were used to estimate the association between ozone and all-cause and cause-specific mortalities. Random-effect meta-analysis and meta-regression analysis were performed to pool the effect estimates of previous studies and examine whether the exposure metric can explain the between-study heterogeneity. The hazard ratios (HRs) per 10 ppb increment in year-round 24-h ozone for all-cause (HR, 1.18; 95% CI, 1.07–1.29) and circulatory (HR, 1.52; 95% CI, 1.25–1.84) mortality were higher than those of the other metrics. Year-round 8-h ozone exhibited the largest association with respiratory mortality (HR, 1.43; 95% CI, 1.04–1.96). A meta-analysis of 29 previous studies and the present study showed the largest HR for all-cause mortality from studies using year-round 8-h exposure (HR, 1.014; 95% CI, 0.994–1.033). The exposure metric was significantly associated with effect estimates in the multivariable meta-regression model. In conclusion, in the population-based cohort in South Korea, we found positive associations between several long-term ozone exposure metrics and mortality. The different ozone exposure metrics exhibited heterogeneous effect estimates. A year-round 24-h average ozone metric also could be considered an alternative long-term standard for ozone.

Children’s respiratory health are particularly vulnerable to outdoor air pollution, but evidence is lacking on the very acute effects of air pollution on the risk of acute upper respiratory infections (AURI) and acute lower respiratory infections (ALRI) in children. This study aimed to evaluate the risk of cause-specific AURI and ALRI, in children within 24 h of exposure to air pollution. We obtained data on emergency cases, including 11,091 AURI cases (acute pharyngitis, acute tonsillitis, acute obstructive laryngitis and epiglottitis, and unspecified acute upper respiratory infections) and 11,401 ALRI cases (pneumonia, acute bronchitis, acute bronchiolitis, unspecified acute lower respiratory infection) in Brisbane, Australia, 2013–2015. A time-stratified case-crossover analysis was used to examine the hourly association of AURI and ALRI with high concentration (95th percentile) of four air pollutants (particulate matters with aerodynamic diameter <10 μm (PM₁₀) and <2.5 μm (PM₂.₅), ozone (O₃), nitrogen dioxide (NO₂)). We observed increased risk of acute tonsillitis associated with PM₂.₅ within 13–24 h (odds ratio (OR), 1.45; 95% confidence interval [CI], 1.02–2.06) and increased risk of unspecified acute upper respiratory infections related to O₃ within 2–6 h (OR, 1.38, 95%CI, 1.12–1.70), NO₂ within 1 h (OR, 1.19; 95%CI, 1.01–1.40), and PM₂.₅ within 7–12 h (OR, 1.21; 95%CI, 1.02–1.43). Cold season and nigh-time air pollution has greater effects on AURI, whereas greater risk of ALRI was seen in warm season and daytime. Our findings suggest exposures to particulate and gaseous air pollution may transiently increase risk of AURI and ALRI in children within 24 h. Prevention measures aimed at protecting children’s respiratory health should consider the very acute effects of air pollution.

Urban turfgrass ecosystems are expected to increase at unprecedented rates in upcoming decades, due to the increasing population density and urban sprawl worldwide. However, so far urban turfgrasses are among the least understood of all terrestrial ecosystems concerning their impact on biogeochemical N cycling and associated nitrous oxide (N₂O) and nitric oxide (NO) fluxes. In this study, we aimed to characterize and quantify annual N₂O and NO fluxes from urban turfgrasses dominated by either C4, warm-season species or C3, cool-season and shade-enduring species, based on year-round field measurements in Beijing, China. Our results showed that soil N₂O and NO fluxes varied substantially within the studied year, characterizing by higher emissions during the growing season and lower fluxes during the non-growing season. The regression model fitted by soil temperature and soil water content explained approximately 50%–70% and 31%–38% of the variance in N₂O and NO fluxes, respectively. Annual cumulative emissions for all urban turfgrasses ranged from 0.75 to 1.27 kg N ha⁻¹ yr⁻¹ for N₂O and from 0.30 to 0.46 kg N ha⁻¹ yr⁻¹ for NO, both are generally higher than those of Chinese natural grasslands. Non-growing season fluxes contributed 17%–37% and 23%–30% to the annual budgets of N₂O and NO, respectively. Our results also showed that compared to the cool-season turfgrass, annual N₂O and NO emissions were greatly reduced by the warm-season turfgrass, with the high root system limiting the availability of inorganic N substrates to soil microbial processes of nitrification and denitrification. This study indicates the importance of enhanced N retention of urban turfgrasses through the management of effective species for alleviating the potential environmental impacts of these rapidly expanding ecosystems.

The response speed of ambulance calls is very crucial to rescue patients suffering immediately life threatening conditions. The serious health outcomes might be caused by exposing to extreme heat only several hours before. However, limited evidence is available on this topic. This study aims to examine the hourly association between heat and ambulance calls, to improve the ambulance services and to better protect health.Hourly data on ambulance calls for non-accidental causes, temperature and air pollutants (PM10, NO2, and O3) were collected from Brisbane, Australia, during 2001 and 2007. A time-stratified case-crossover design was used to examine the associations between hourly ambulance calls and temperature during warm season (Nov, Dec, Jan, Feb, and Mar), while adjusting for potential confounders. Stratified analyses were performed for sex and age groups.Ambulance calls peaked at 10am for all groups, except those aged <15 years at 19pm, while temperature was hottest at 13pm. The hourly heat-ambulance calls relationships were non-linear for all groups, with thresholds between 27 °C and 31 °C. The associations appeared immediately, and lasted for about 24 h. There were no significant modification effect by sex and age.The findings suggest that hot hourly temperatures (>27 °C) increase the demands of ambulance. This information is helpful to increase the efficiency of ambulance service then save lives, for example, preparing more ambulance before appearance of extremely hot temperature in combination with weather forecast. Also, people should better arrange their time for outdoor activities to avoid exposing to extreme hot temperatures.

Toxic organic substances and polar organic marker compounds, i.e. polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs) and their nitro-derivatives (N-PAHs), as well as dicarboxylic acids (DCAs) and sugars/sugar anhydrites (S/SAs) were analyzed in size-segregated PM samples (<0.49, 0.49–0.97, 0.97–3 and >3 μm) collected at two urban sites (urban traffic and urban background) during the cold and the warm season. The potential associations between the organic PM determinants and the adverse cellular effects (i.e. cytotoxicity, genotoxicity, DNA damage, oxidative DNA adduct formation, and inflammatory response) induced by the extractable organic matter (EOM) of PM, previously measured in Velali et al. (2016b), were investigated by bivariate correlations and Principal Component Analysis (PCA). Partial Least Square regression analysis (PLS) was also employed in order to identify the chemical classes mainly involved in the EOM-induced toxicological endpoints in the various particle size fractions. Results indicated that particle size range <0.49 μm was the major carrier of PM mass and organic compounds at both sites. All toxic organic compounds exhibited higher concentrations at the urban traffic site, except PCBs and OCPs that did not exhibit intra-urban variations. Conversely, wintertime levels of levoglucosan were significantly higher at the urban background site as a result of residential biomass burning. The PLS regression analysis allowed quite good prediction of the EOM-induced cytotoxicity and genotoxicity based on the determined organic chemical classes, particularly for the finest size fraction of PM. Nevertheless, it is expected that other chemical constituents, not determined here, also contribute to the measured toxicological responses.

In this study, the top-down NOx emissions estimated from satellite observations of NO2 vertical column densities over North Korea from 1996 to 2009 were analyzed. Also, a bottom-up NOx emission inventory from REAS 1.1 from 1980 to 2005 was analyzed with several statistics. REAS 1.1 was in good agreement with the top-down approach for both trend and amount. The characteristics of NOx emissions in North Korea were quite different from other developed countries including South Korea. In North Korea, emissions from industry sector was the highest followed by transportation sector in the 1980s. However, after 1990, the NOx emissions from other sector, mainly agriculture, became the 2nd highest. Also, no emission centers such as urban areas or industrial areas were distinctively observed. Finally, the monthly NOx emissions were high during the warm season.

Air pollution has been accepted as an important contributor to asthma development and exacerbation. However, the evidence is limited in China. In this study, we investigated the acute effect of air pollution on asthma hospitalization in Shanghai, China. We applied over-dispersed generalized additive model adjusted for weather conditions, day of the week, long-term and seasonal trends. An interquartile range increase in the moving average concentrations of PM10, SO2, NO2 and BC on the concurrent day and previous day corresponded to 1.82%, 6.41%, 8.26% and 6.62% increase of asthmatic hospitalization, respectively. The effects of SO2 and NO2 were robust after adjustment for PM10. The associations appeared to be more evident in the cool season than in the warm season. Our results contribute to the limited data in the scientific literature on acute effects of air pollution on asthma in high exposure settings, which are typical in developing countries.

Warm season (May–October) chloride concentrations were assessed in stream habitats of freshwater mussel species at risk in southern Ontario, Canada. Significant increases in concentrations were observed at 96% of 24 long-term (1975–2009) monitoring sites. Concentrations were described as a function of road density indicating an anthropogenic source of chloride. Linear regression showed that 36% of the variation of concentrations was explained by road salt use by the provincial transportation ministry. Results suggest that long-term road salt use and retention is contributing to a gradual increase in baseline chloride concentrations in at risk mussel habitats. Exposure of sensitive mussel larvae (glochidia) to increasing chloride concentrations may affect recruitment to at risk mussel populations.

This study reports a general assessment of the organic composition of the PM₂.₅ samples collected in the city of Augsburg, Germany in a summer (August–September 2007) and a winter (February–March 2008) campaign of 36 and 30 days, respectively. The samples were directly submitted to in-situ derivatisation thermal desorption gas chromatography coupled with time of flight mass spectrometry (IDTD–GC–TOFMS) to simultaneously determine the concentrations of many classes of molecular markers, such as n-alkanes, iso- and anteiso-alkanes, polycyclic aromatic hydrocarbons (PAHs), oxidized PAHs, n-alkanoic acids, alcohols, saccharides and others. The PCA analysis of the data identified the contributions of three emission sources, i.e., combustion sources, including fossil fuel emissions and biomass burning, vegetative detritus, and oxidized PAHs. The PM chemical composition shows seasonal trend: winter is characterized by high contribution of petroleum/wood combustion while the vegetative component and atmospheric photochemical reactions are predominant in the hot season.

Ambient ozone (O₃) pollution has become a big issue in China. Recent studies have linked long- and short-term O₃ exposure to several public health risks. In this study, we (1) characterize the long-term and short-term O₃-attributed health metric in China from 2015 to 2019; (2) estimate the surface O₃ trends; and (3) quantify the long-term and short-term health impacts (i.e. all-cause, cardiovascular and respiratory mortality) in 350 urban Chinese cities. In these 5-years, the national annual average of daily maximum 8 h average (AVGDMA8) O₃ concentrations and warm-season (April–September) 4th highest daily maximum 8 h average (4DMA8) O₃ concentrations increased from 74.0 ± 15.5 μg/m³ (mean ± standard deviation) to 82.3 ± 12.0 μg/m³ and 167 ± 37.0 μg/m³ to 174 ± 30.0 μg/m³ respectively. During this period, the DMA8 O₃ concentration increased by 1.9 ± 3.3 μg/m³/yr across China, with over 70% of the monitoring sites showing a positive upward trend and 19.4% with trends >5 μg/m³/yr. The estimated long-term all-cause, cardiovascular and respiratory premature mortalities attributable to AVGDMA8 O₃ exposure in 350 Chinese cities were 181,000 (95% CI: 91,500–352,000), 112,000 (95% CI: 38,100–214,000) and 33,800 (95% CI: 0–71,400) in 2019, showing increases of 52.5%, 52.9% and 54.6% respectively compared to 2015 levels. Similarly, short-term all-cause, cardiovascular and respiratory premature mortalities attributed to ambient 4DMA8 O₃ exposure were 156,000 (95% CI: 85,300–227,000), 73,500 (95% CI: 27,500–119,000) and 28,600 (95% CI: 14,500–42,800) in 2019, increases of 19.6%, 19.8% and 21.2% respectively compared to 2015. The results of this study are important in ascertaining the effectiveness of recent emission control measures and to identify the areas that require urgent attention.