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Abstract The World Health Organization sets up the Ambient Air Quality Guidelines mainly based on short-term and long-term health effects of air pollution. Previous studies, however, have generally revealed a non-threshold concentration-response relationship between air pollution and health, making it difficult to determine a concentration, below which no obvious health effects can be observed. Here we proposed a novel approach based on the concept of "number needed to treat", specifically, we calculated the reduction in air pollution concentrations needed to avoid one death corresponding to different hypothetical concentration standards; the one with the smallest value would be the most practical concentration standard. As an example, we applied this approach to the daily standard of ambient PM 2.5 (particulate matter with aerodynamic diameter ≤2.5 μm) in four Chinese cities. The calculation was based on the association between daily mortality and ambient PM 2.5 , which was examined by a generalized additive model with adjustment of important covariates. Significant associations were observed between PM 2.5 and mortality. Our analyses suggested that it is appropriate to have 50 μg/m3 as the daily standard of ambient PM 2.5 for the study area, compared to the current standard of which were directly adopted from the national standard of 75 μg/m3. This novel approach should be considered when planning and/or revising the ambient air quality guidelines/standards. Highlights • There is limited method for air pollution standard formulation. • The "number needed to treat" was proposed as one potential method. • We examined the acute association between PM 2.5 and mortality in four Chinese cities. • We then calculated the reduction in air pollution concentrations needed to avoid one death. • Finally, we suggested that 50 μg/m3 should be considered as daily standard of ambient PM 2.5 in the study area. Capsule This study proposes a new "number needed to treat" approach to help establish or revise daily ambient air quality standards. [ABSTRACT FROM AUTHOR]

Three bacterial strains capable of transforming pyrazosulfuron-ethyl, designated as D61, D66, and D713, were isolated from pyrazosulfuron-ethyl contaminated soils. According to the sequence analysis of the partial 16S rRNA gene, it is found that the strains D61 and D66 belong to Pseudomonas sp., and the strain D713 belongs to Bacillus sp. The effects of pyrazosulfuron-ethyl concentration, pH and temperature on biodegradation were examined. At a concentration of 10.0mgL−1, pyrazosulfuron-ethyl was completely degraded by Pseudomonas sp. D61 after 2d and by Pseudomonas sp. D66 after 5d. At a concentration of 90.0mgL−1, pyrazosulfuron-ethyl can be completely degraded by Pseudomonas sp. D66 and D61 after 12d. More than 85.9% degradation rate was observed with Bacillus sp. D713 after 12d. The growth of these three strains was inhibited at low pH buffers. The abiotic degradation occurs much faster at low pH than at neutral and basic pH conditions. The degradation rate of pyrazosulfuron-ethyl at 28°C was faster than those at 20°C and 37°C by these strains, except the highest degradation rate of Bacillus sp. D713 was obtained at 37°C. The pyrazosulfuron-ethyl biodegradation products were identified by liquid chromatography–mass spectroscopy with positive/negative modes and tandem MS–MS techniques. The main degradation product was detected and identified as 5-(N-(4,6-dimethoxypyrimidin-2-ylcarbamoyl)sulfamoyl)-1-methyl-1H-pyrazole-4-carboxylic acid based on mass spectral data and fragmentation patterns. [Copyright &y& Elsevier]

Previous research has reported the effects of long-term fine particulate matter (PM 2.5) pollution on years of life lost (YLL), but these effects may not represent the full impact. This study aims to estimate potential benefits in life time from adhering to daily ambient PM 2.5 concentration standards/guidelines. This study evaluated the relationship between daily ambient PM 2.5 level and YLL using a two-stage approach with generalized additive models and meta-analysis. Potential life expectancy gains were then estimated by presuming that daily PM 2.5 levels were in compliance with the Chinese and WHO standards. In addition, the attributable fraction of YLL due to excess PM 2.5 exposure was also calculated. During 2013–2016, 459,468 non-accidental deaths were recorded in the six cities of Pearl River Delta, China. Each 10 μg/m3 increment in four-day average (lag 03) level of PM 2.5 was related to an increment of 13.31 [95% confidence interval (CI): 5.74, 20.87] years of life lost. Implementation of the WHO guidelines might avoid 180,980.83 YLLs (95% CI: 78,116.07, 283,845.60), which corresponded to 0.39 (95% CI: 0.17, 0.62) years of increased life time per death. Additionally, an estimated 0.15% (95% CI: 0.06%, 0.23%) or 2.04% (95% CI: 0.88%, 3.20%) of YLLs could be attributed to PM 2.5 exposures higher than the Chinese or WHO guidelines, respectively. This study suggests that people might live longer by controlling daily PM 2.5 concentration and highlights the need to adopt stricter standards in China. • We estimated the life time gain by attaining daily PM 2.5 standards. • Life time might increase by 0.39 years for each death by attaining WHO's guideline. • Up to 2.04% of YLL could be ascribed to PM 2.5 exposure higher than WHO's guideline. • More ambitious target for PM 2.5 control should be employed to improve public health. [ABSTRACT FROM AUTHOR]

Heavy metals play an important role in inducing fine particulate matter (PM 2.5) related cardiovascular disease (CVD). However, most of the past researches concerned the associations between CVD mortality and the PM 2.5 mass, which may not reveal the CVD mortality risk contributed by heavy metals in PM 2.5. This study explored the correlations between individual heavy metals in PM 2.5 and CVD mortality, identified the heavy metals that significantly contribute to PM 2.5 -related CVD, heart disease (HD), and cerebrovascular disease (CEV) mortality, and attempted to establish corresponding source control measures. Over a 2-year study period, PM 2.5 was sampled daily in Guangzhou, China and analyzed for heavy metals. The airborne pollution and weather data, along with CVD, HD, and CEV mortality, were obtained at the same time. The excess risk (ER) of mortality was linked to the individual heavy metals using a distributed lag non-linear model. PM 2.5 and most heavy metals showed significant correlations with the CVD, HD, and CEV mortality; the largest cumulative ER (LCER) values of CVD mortality associated with an interquartile range increase in the levels of lead, cadmium, arsenic, selenium, antimony, nickel, thallium, aluminum, iron, and PM 2.5 were 2.43%, 2.23%, 1.66%, 2.39%, 1.19%, 1.21%, 2.69%, 3.29%, 1.74%, and 2.40%, respectively. Most heavy metals showed comparable LCER values of HD and CEV mortality. Heavy metals with the addition of PM 2.5 were divided into three groups following their LCER values; lead, cadmium, arsenic, antimony, thallium, zinc, aluminum, and iron, whose contributions were greater than or equal to the average effect of the PM 2.5 components, should be limited on a priority basis. These findings indicated that heavy metals play roles in the CVD, HD, and CEV mortality risk of PM 2.5 , and specific control measures which aimed at the emission sources should be taken to reduce the CVD mortality risk of PM 2.5. [Display omitted] • Daily levels of heavy metals in PM 2.5 were analyzed from a 2-year sampling. • Nine heavy metals in PM 2.5 were significantly associated with CVD mortality. • Precise source control of Pb, Cd, Se, Sb, Tl, Zn, Al, and Fe should be conducted. [ABSTRACT FROM AUTHOR]