Indoor air quality is critically important to the human as people spend most time indoors. Indoor PM₂.₅ is related to the outdoor levels, but more directly influenced by internal sources. Severe household air pollution from solid fuel use has been recognized as one major risk for human health especailly in rural area, however, the issue is significantly overlooked in most national air quality controls and intervention policies. Here, by using low-cost sensors, indoor PM₂.₅ in rural homes burning coals was monitored for ~4 months and analyzed for its temporal dynamics, distributions, relationship with outdoor PM₂.₅, and quantitative contributions of internal sources. A bimodal distribution of indoor PM₂.₅ was identified and the bimodal characteristic was more significant at the finer time resolution. The bimodal distribution maxima were corresponding to the emissions from strong internal sources and the influence of outdoor PM₂.₅, respectively. Indoor PM₂.₅ was found to be correlated with the outdoor PM₂.₅, even though indoor coal combustion for heating was thought to be predominant source of indoor PM₂.₅. The indoor-outdoor relationship differed significantly between the heating and non-heating seasons. Impacts of typical indoor sources like cooking, heating associated with coal use, and smoking were quantitatively analyzed based on the highly time-resolved PM₂.₅. Estimated contribution of outdoor PM₂.₅ to the indoor PM₂.₅ was ~48% during the non-heating period, but decreased to about 32% during the heating period. The contribution of indoor heating burning coals comprised up to 47% of the indoor PM₂.₅ during the heating period, while the other indoor sources contributed to ~20%. The study, based on a relatively long-term timely resolved PM₂.₅ data from a large number of rural households, provided informative results on temporal dynamics of indoor PM₂.₅ and quantitative contributions of internal sources, promoting scientific understanding on sources and impacts of household air pollution.

Both air pollution and dyslipidemias contributed to large number of deaths and disability-adjusted life lost years. Long-term air pollution exposure was related to changed blood lipids and risk of dyslipidemias. This study was designed to evaluate relationships between air pollutants, blood lipids and prevalence of dyslipidemias in a Chinese rural population exposed to high-level air pollution based on baseline data of The Henan Rural Cohort study. An amount of 39,057 participants from rural areas in China were included. The 3-year average exposure of air pollutants (PM2.5, PM10, NO2) was estimated by a spatiotemporal model. Logistic and linear regression models were employed to explore relationships between air pollutants, blood lipids (TC, TG, HDL-C and LDL-C) and prevalence of dyslipidemias. The three-year concentration of PM2.5, PM10 and NO2 was 72.8 ± 2.3 μg/m3, 131.5 ± 5.7 μg/m3and 39.1 ± 3.1 μg/m3, respectively. Overall, increased air pollution exposure was related to increased TC and LDL-C, while decreased TG and HDL-C. Each 1-μg/m3 increment of PM2.5 was related to 0.10% (0.07%–0.19%) increase in TC, 0.63% (0.50%–0.77%) increase in LDL-C, 2.93% (2.70%–3.16%) decrease in TG, 0.49% (0.38%–0.60%) decrease in HDL-C; and 5.7% (95%CI: 3.7%–7.6%), 4.0% (95%CI: 2.1%–6.0%) and 3.8% (95%CI: 2.5%–5.1%) increase in odds for hypercholesterolemia, hyperbetalipoproteinemia and hypoalphalipoproteinemia, respectively. Stronger associations were found in male and older participants. Findings suggest that air pollutants were associated with changed blood lipid levels and higher risk of dyslipidemias among rural population. Male and elder people should pay more attention to personal safety protection.

The association between temperature and mortality has been widely reported. However, it remains largely unclear whether inflammation-related diseases, caused by excessive or inappropriate inflammatory reaction, may be affected by ambient temperature, particularly in low-income areas.To explore the association between ambient temperature and clinical visits for inflammation-related diseases in rural villages in the Ningxia Hui Autonomous Region, China, during 2012─2015.Daily data on inflammation-related diseases and weather conditions were collected from 258 villages in Haiyuan (161 villages) and Yanchi (97 villages) counties during 2012─2015. A Quasi-Poisson regression with distributed lag non-linear model was used to examine the association between temperature and clinical visits for inflammation-related diseases. Stratified analyses were performed by types of diseases including arthritis, gastroenteritis, and gynecological inflammations.During the study period, there were 724,788 and 288,965 clinical visits for inflammation-related diseases in Haiyuan and Yanchi, respectively. Both exposure to low (RR: 2.045, 95% CI: 1.690, 2.474) and high temperatures (RR: 1.244, 95% CI: 1.107, 1.399) were associated with increased risk of total inflammation-related visits in Haiyuan county. Low temperatures were associated with increased risks of all types of inflammation-related diseases in Yanchi county (RR: 4.344, 95% CI: 2.887, 6.535), while high temperatures only affected gastroenteritis (RR: 1.274, 95% CI: 1.040, 1.561). Moderate temperatures explained approximately 26% and 33% of clinical visits due to inflammation-related diseases in Haiyuan and Yanchi, respectively, with the burden attributable to cold exposure higher than hot exposure. The reference temperature values ranged from 17 to 19 in Haiyuan, and 12 to 14 in Yanchi for all types of clinical visits.Our findings add additional evidence for the adverse effect of suboptimal ambient temperature and provide useful information for public health programs targeting people living in rural villages.

This study was designed to investigate the seasonal characteristics and apportion the sources of organic carbon during non-haze days (<75 μg m⁻³) and haze (≥75 μg m⁻³) events at Pinggu, a rural Beijing site. Time-resolved concentrations of carbonaceous aerosols and organic molecular tracers were measured during the winter of 2016 and summer 2017, and a Chemical Mass Balance (CMB) model was applied to estimate the average source contributions. The concentration of OC in winter is comparable with previous studies, but relatively low during the summer. The CMB model apportioned seven separate primary sources, which explained on average 73.8% on haze days and 81.2% on non-haze days of the organic carbon in winter, including vegetative detritus, biomass burning, gasoline vehicles, diesel vehicles, industrial coal combustion, residential coal combustion and cooking. A slightly lower percentage of OC was apportioned in the summer campaign with 64.5% and 78.7% accounted for. The other unapportioned OC is considered to consist of secondary organic carbon (SOC). During haze episodes in winter, coal combustion and SOC were the dominant sources of organic carbon with 23.3% and 26.2%, respectively, followed by biomass burning emissions (20%), whereas in summer, industrial coal combustion and SOC were important contributors. Diurnal contribution cycles for coal combustion and biomass burning OC showed a peak at 6–9 pm, suggesting domestic heating and cooking were the main sources of organic aerosols in this rural area. Backward trajectory analysis showed that high OC concentrations were measured when the air mass was from the south, suggesting that the organic aerosols in Pinggu were affected by both local emissions and regional transport from central Beijing and Hebei province during haze episodes. The source apportionment by CMB is compared with the results of a Positive Matrix Factorization (PMF) analysis of ACSM data for non-refractory PM₁, showing generally good agreement.

Persistent organic pollutants (POPs) including PCDD/Fs, PCBs and organochlorine pesticides (OCPs) are among the most important and hazardous pollutants of soil. Food producing animals such as chicken, beef, sheep and goats can take up soil while grazing or living outdoors (free-range) and this can result in contamination.In recent decades, large quantities of brominated flame retardants such as polybrominated diphenyl ethers (PBDEs), short-chain chlorinated paraffins (SCCPs) and per- and polyfluorinated alkylated substances (PFAS) have been produced and released into the environment and this has resulted in widespread contamination of soils and other environmental matrices. These POPs also bioaccumulate and can contaminate food of animal origin resulting in indirect exposure of humans.Recent assessments of chicken and beef have shown that surprisingly low concentrations of PCBs and PCDD/Fs in soil can result in exceedances of regulatory limits in food. Soil contamination limits have been established in a number of countries for PCDD/Fs but it has been shown that the contamination levels which result in regulatory limits in food (the maximum levels in the European Union) being exceeded, are below all the existing soil regulatory limits. ‘Safe’ soil levels are exceeded in many areas around emission sources of PCDD/Fs and PCBs. On the other hand, PCDD/F and dioxin-like PCB levels in soil in rural areas, without a contamination source, are normally safe for food producing animals housed outdoors resulting in healthy food (e.g. meat, eggs, milk).For the majority of POPs (e.g. PBDEs, PFOS, PFOA, SCCP) no regulatory limits in soils exist.There is, therefore, an urgent need to develop appropriate and protective soil standards minimising human exposure from food producing animals housed outdoors. Furthermore, there is an urgent need to eliminate POPs pollution sources for soils and to control, secure and remediate contaminated sites and reservoirs, in order to reduce exposure and guarantee food safety.

Inhalation exposure to atmospheric polycyclic aromatic hydrocarbons (PAHs) is posing a great threat to human health. Biomass combustion in rural areas contributes greatly to the total PAH emission in China. To conduct a comprehensive risk assessment of ambient PAHs in rural China, a nationwide air sampling campaign was carried out in this study. The 16 U.S. Environmental Protection Agency priority PAHs in tree bark, which was employed as a passive air sampler, were analyzed. The summation of the 16 PAHs ranged from 11.7 to 12,860 ng/m³ in the air of rural China. The national median benzo(a)pyrene equivalent (BaPₑq) concentration was 18.4 ng/m³, with the range from 0.334 to 2497 ng/m³. The total inhalation carcinogenic risks of individual PAHs, with the exception for naphthalene, were very low (<1 × 10⁻⁶) at most of the sampling sites. The national median excess lifetime lung cancer risk associated with inhalation exposure to atmospheric PAHs was 20.3 × 10⁻⁶, corresponding to a population attributable fraction (PAF) of 3.38‰. Our estimations using tree bark were comparable to those reported in other studies and the uncertainties of the variables in the dataset were within the acceptable levels, demonstrating that tree bark is feasible for assessing the atmospheric PAH pollution and associated health risks. We feel that the outputs from this study can assist decision-makers focusing on protecting human health against exposure to atmospheric PAHs in rural China.

Antibiotic resistance among gram-negative bacteria is increasingly becoming a problem of global concern. Particularly problematic is the emergence of resistance to last-resort antibiotics such as carbapenems and colistin. The increasing number of reports on the plasmid-mediated colistin resistance gene mcr-1 in isolates worldwide is raising concerns for the future usefulness of this class of antibiotics. Dissemination of mcr-1 is believed to have originated mainly from animal breeding, however, the role of the environment as a transmission source is not yet fully understood. In the current study, 89 extended-spectrum β-lactamase-producing Escherichia coli isolated from 231 samples from different environmental sources in 12 villages in a rural area of Shandong, China, were screened for mcr-1. 17 (19.1%) mcr-1-positive isolates were found from different environmental sources, aggregated in 6 villages. Plasmids of three different Inc-groups carrying mcr-1 were confirmed, indicating that the widespread geographical distribution of mcr-1 in the local area is due to a number of different plasmids. Additionally, almost a third (29.4%) of the isolates carried virulence factors associated to intestinal pathogenic E. coli. These results illustrate the high complexity of the transmission patterns of mcr-1 among different environmental matrices on a local scale and the potential for the environment to facilitate dissemination and emergence of antibiotic-resistant and virulent strains of bacteria.

Moss (as a reference material) and camphor (Cinnamomum Camphora) leaf, branch bark and bark samples were systematically collected across an urban-rural gradient in Guiyang (SW China) to determine the efficacy of using these bio-indicators to evaluate nitrogen (N) pollution. The tissue N concentrations (0.13%–2.70%) and δ¹⁵N values (−7.5‰ to +9.3‰) of all of these bio-indicators exhibited large spatial variations, as they recorded higher values in urban areas that quickly decreased with distance from the city center; moreover, both soil N concentrations and soil δ¹⁵N values were found no significant differences within each 6 km from the urban to the rural area. This not only suggests that the different N uptake strategies and variety of N responses of these bio-indicators can be reflected by their different susceptibilities to variations in N deposition but also reveals that they are able to indicate that urban N deposition is mostly from traffic and industry (NOₓ-N), whereas rural N deposition is mainly from agriculture (NHₓ-N). Compared to previously collected urban moss and camphor leaf samples, the significantly increased δ¹⁵N values in current urban moss and camphor leaf samples further indicate a greater contribution of NOₓ-N than NHₓ-N to urban N deposition. The feasibility of using the N concentrations and δ¹⁵N values of branch bark and bark as biomarkers of N deposition thus was further confirmed through the comparative use of these bio-indicators. It can be concluded that vascular plant leaves, branch bark and bark can be used as useful biomonitoring tools for evaluating atmospheric N pollution. For further study, quantitative criteria for the practical use of these bio-indicators in response to N deposition should be developed and the differences in the δ¹⁵N values of different plant parts should also be considered, particularly in urban environments that are severely disrupted by atmospheric pollution.

For human health benefits it is crucial to see if carcinogenic air pollutants like polycyclic aromatic hydrocarbons (PAHs) are reduced accordingly along with the control of the criteria pollutants including fine particles (PM₂.₅). A number of studies documented that enhanced temporary emission control during the 2014 Asia-Pacific Economic Cooperation summit (APEC) in Beijing resulted in substantial drops of observed ambient PM₂.₅, as well as PAHs, in urban areas of Beijing, yet it is not clear whether PM₂.₅-bound PAHs in the rural areas were also lowered during the APEC. Here filter-based PM₂.₅ samples were collected at a rural site in northeast of Beijing, and analyzed for 25 PAHs before (Oct. 27-Nov. 2, 2014), during (Nov. 3–12, 2014) and after (Nov. 13, 2014–Jan. 14, 2015) the APEC. Observed concentrations of PM₂.₅, OC and EC during the APEC dropped by about 30%, however, average PM₂.₅-bound PAHs and their incremental lifetime cancer risk (ILCR), 25.65 ng/m³ and 3.2 × 10⁻⁴, remained almost unchanged when compared to that of 25.48 ng/m³ and 3.5 × 10⁻⁴, respectively, before the APEC. After the APEC with the start of wintertime central heating in urban Beijing on Nov. 15, 2014, average total concentration of PAHs and their ILCR highly elevated and reached 118.25 ng/m³ and 1.5 × 10⁻³, respectively. Source apportioning by positive matrix factorization (PMF) revealed that coal combustion was the largest source that contributed 63.2% (16.1 ng/m³), 78.5% (20.1 ng/m³) and 56.1% (66.3 ng/m³) to the total PAHs before, during and after the APEC, respectively. Uncontrolled residential coal use during the APEC was found to be the reason for unabated levels of PAHs, and the largely aggravated PAHs after the APEC was resulted from increased coal consumption for wintertime residential heating. Our results suggested reducing emission from residential coal combustion is crucial to mitigate carcinogenic PAHs in ambient air, especially in rural areas.