The deep blue day is decreasing in China

Wang, Su; Huang, Gang; Hu, Kaiming; Lin, Wang; Dai, Tie; Zhou, Chunjiang

doi:10.1007/s00704-021-03898-1

Cited by 2 publications

(2 citation statements)

References 72 publications

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“…This set of standards could capture almost all well-known blue events in China (APEC Blue, etc.) (24). We calculated the number of blue days at baseline survey year as the measurement of blue day exposure.…”

Section: Blue Day Exposure Assessmentmentioning

confidence: 99%

Blue sky as a protective factor for cardiovascular disease

Tang

Zheng

Cao

et al. 2022

Front. Public Health

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ObjectiveBlue sky has been considered to boost outdoor physical activity and social interaction, ameliorate work pressure and life stress, and enhance people's sense of happiness. However, the direct association between blue sky exposure and cardiovascular disease (CVD) still lacks epidemiological evidence. In this study, we aimed to quantify their relationship via a nationwide prospective cohort in China.MethodWe extracted the baseline data from the China Hypertension Survey (CHS), by enrolling 22,702 participants aged ≥ 35 years without self-reported medical history of CVD from 14 provinces of China between 2012 and 2015 and followed up from 2018 to 2019. A blue day was marked out with no rain, low cloud cover ≤ climatological mean at each station, and visibility at 2 pm ≥ 21.52 km. We calculated the number of blue days at baseline survey year to evaluate the chronic individual blue day exposure. Cox proportional hazards models were employed to calculate the multivariable-adjusted hazard ratio (HR). We implemented subgroup analyses as well to identify potential effect modifications.ResultsA total of 1,096, 993, and 597 incident cases of all-cause mortality, fatal or nonfatal CVD, and stroke occurred during a median follow-up around 5 years, respectively. A 10-day increase in annual blue day exposure was associated with a 3% (95% confidence interval [CI]: 1–6%) and 7% (95% CI: 5–10%) decreased risk of fatal or nonfatal CVD and stroke, respectively. Compared with those exposed to the worst tertile of blue days at baseline, subjects who exposed to the best tertile had a 32% (95% CI: 19–43%) and 43% (95% CI: 29–55%) lower likelihood of developing fatal or nonfatal CVD and stroke, respectively. Negative consistent exposure–response relationships were generally observed between them in the restricted cubic spline model. In the stratified analyses, the cardioprotective effects of blue sky were stronger for females, rural residents, and individuals residing in heavily contaminated areas.ConclusionThis study indicates that blue sky may serve as an independent environmental protective factor against CVD, and informs future policies on fighting air pollution and protecting the blue sky in China.

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Section: Blue Day Exposure Assessmentmentioning

confidence: 99%

Blue sky as a protective factor for cardiovascular disease

Tang

Zheng

Cao

et al. 2022

Front. Public Health

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“…However, the low visibility events occur frequently despite the PM 2.5 mitigation (Xu et al., 2020). The deep blue day, which requires the visibility to be larger than 21.52 km, even decreased in China from 1980 to 2018 (S Wang et al., 2022), which indicates that the visibility repairment lags behind the reduction of PM 2.5 . PM 2.5 was brought down by 30% while the low visibility frequency in the Pearl River Delta regions decreased by only 5% (Xu et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Current Challenges in Visibility Improvement in Sichuan Basin

Zhao

Zhang

et al. 2022

Geophysical Research Letters

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Atmospheric visibility (VIS), reflecting the atmosphere transmittance, is an important indicator of air quality (Bäumer et al., 2008). Low visibilities exert significant influences on transportation, especially air traffic (Sun et al., 2021), and thus decrease society efficiencies. China has suffered from air pollution with the rapid economic growth over the past years and the visibility deterioration in China has raised public awareness (Guo et al., 2014). The Chinese government has made many efforts to improve haziness including various strategies of emission control since the issuing of the Air Pollution Prevention Control and Action Plan in 2013. PM 2.5 , NO x , and SO 2 were observed to reduce by 33%, 21%, and 59%, respectively (Zheng et al., 2018). However, the low visibility events occur frequently despite the PM 2.5 mitigation (Xu et al., 2020). The deep blue day, which requires the visibility to be larger than 21.52 km, even decreased in China from 1980 to 2018 (S Wang et al., 2022), which indicates that the visibility repairment lags behind the reduction of PM 2.5 . PM 2.5 was brought down by 30% while the low visibility frequency in the Pearl River Delta regions decreased by only 5% (Xu et al., 2020). The increased aerosol extinction efficiency hinders visibility improvement in Eastern China despite that the PM 2.5 level was reduced by 50.8 μg/m 3 (Yao et al., 2021). More efforts should be devoted to visibility repairment along with the reduction of PM 2.5 .By definition, visibility is the distance at which an observer can barely recognize a black object, and the basic formula of atmospheric visibility is VIR = Inε/σ where ε is a contrast threshold of the observer, and σ is the

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The deep blue day is decreasing in China

Cited by 2 publications

References 72 publications

Blue sky as a protective factor for cardiovascular disease

Blue sky as a protective factor for cardiovascular disease

Current Challenges in Visibility Improvement in Sichuan Basin

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