Sorely reducing emissions of non-methane short-lived climate forcers will worsen compound flood-heatwave extremes in the Northern Hemisphere

Non-methane short-lived climate forcer(SLCF)or near-term climate forcer(NTCF)emissions,as a significant driver of climate change,can be reduced to improve air quality.These reductions may contribute to additional warming of the climate system in the short term,thereby strongly affecting the likelihood of climate extremes.However,there has been no quantitative assessment of the impact of non-methane SLCF mitigation on compound flood-heatwave extremes(CFHEs).This study quantitatively investigates the changes in future(2031-2050 versus 1995-2014)CFHEs and the resulting population exposure in the Northern Hemisphere(NH)due to non-methane SLCF reductions.We used multi-model ensemble simulations under two future scenarios from the Aerosol and Chemistry Model Intercomparison Project(AerChemMIP)in the Coupled Model Intercomparison Project Phase 6(CMIP6).The two future scenarios share the same greenhouse gas(GHG)emissions but have weak(Shared Socioeconomic Pathway(SSP)3-7.0)versus strong(SSP3-7.0-lowNTCF)levels of air quality control measures.The results show that future non-methane SLCF reductions during 2031-2050 results in about a 7.3%±2.3%increase in grid exposure to CFHEs in the NH relative to the period 1995-2014.The frequency,intensity,and duration of CFHEs increase by varying degrees.During the period 2031-2050,the frequency of CFHEs across the NH increases by 2.9±0.9 events per decade due to non-methane SLCF reductions.The increases in CFHE frequency are more pronounced in East Asia,South Asia,Siberia,and northern and eastern North America.In East and South Asia,the in-tensities of both heatwaves and floods corresponding to CFHEs increase markedly,where heatwave magnitude(HWM)increases by 0.3±0.2 K in East Asia and weighted average precipitation(WAP)increases by 18.3%±15.3%and 12.0%±4.5%in East Asia and South Asia,respectively.In other regions,rising temperatures dominate the increase in CFHEs.With regard to the duration of CFHEs,future reductions in non-methane SLCFs increases the duration of CFHEs in the NH by O.3±0.1 d.Regionally,the sensitivity of CFHE frequency to global warming caused by non-methane SLCF mitigation is 1.2-1.9 times higher than that caused by GHG forcing.Non-methane SLCFs results in NH-averaged increases in population exposure to CFHEs of(5.0±2.0)×10^(5)person·event in the period 2031-2050.This study emphasizes the importance of considering the impacts of cleaner air in future responses to compound extremes and corresponding societal planning.

Sources of ambient non-methane hydrocarbon compounds and their impacts on O_(3) formation during autumn,Beijing

The field observation of 54 non-methane hydrocarbon compounds(NMHCs)was conducted from September 1 to October 20 in 2020 during autumn in Haidian District,Beijing.The mean concentration of total NMHCs was 29.81±11.39 ppbv during this period,and alkanes were the major components.There were typical festival effects of NMHCs with lower concentration during the National Day.Alkenes and aromatics were the dominant groups in ozone formation potential(OFP)and OH radical loss rate(L_(OH)).The positive matrix factorization(PMF)running results revealed that vehicular exhaust became the biggest source in urban areas,followed by liquefied petroleum gas(LPG)usage,solvent usage,and fuel evaporation.The box model coupled with master chemical mechanism(MCM)was applied to study the impacts of different NMHCs sources on ozone(O_(3))formation in an O_(3)episode.The simulation results indicated that reducing NMHCs concentration could effectively suppress O_(3)formation.Moreover,reducing traffic-related emissions of NMHCs was an effective way to control O_(3)pollution at an urban site in Beijing.

Evaluation of offline sampling for atmospheric C3-C11 non-methane hydrocarbons

The concentration variation of C3-C11 non-methane hydrocarbons(NMHCs)collected in several types of commercial flexible bags and adsorption tubes was systematically inves-tigated using a gas chromatography-flame ionization detector(GC-FID)system.The per-centage loss of each NMHC in the polyvinyl fluoride(PVF)bags was less than 5%during a 7-hr storage period;significant NMHCs loss was detected in aluminum foil composite film and fluorinated ethylene propylene bags.The thermal desorption efficiency of NMHCs for adsorption tubes filled Carbopack B and Carboxen1000 sorbents was greater than 95%at 300℃,and the loss of NMHCs in the adsorption tubes during 20-days storage at 4℃was less than 8%.The thermal desorption efficiency for C11 NMHCs in the adsorption tube filled with Carbograph 1 and Carbosieve SⅢabsorbents was less than 40%at 300℃,and pyrolysis of the absorbents at 330℃interfered significantly with the measurements of some alkenes.The loss of alkenes was significant when NMHCs were sampled by cryo-enrichment at-90℃in the presence of O3 for the online NMHC measurements,and negligible for enrichment us-ing adsorption tubes at 25℃.Although O_(3)scrubbers have been widely used to eliminate the influence of O_(3)on NMHC measurements,the loss of NMHCs with carbon numbers greater than 8 was more than 10%.Therefore,PVF bags and adsorption tubes filled Carbopack B and Carboxen1000 sorbents were recommended for the sampling of atmospheric NMHCs.

Relationships between emissions of toxic airborne molecules and type 1 diabetes incidence in children:An ecologic study

BACKGROUND Type 1 diabetes originates from gene-environment interactions,with increasing incidence over time.AIM To identify correlates of childhood type 1 diabetes in European countries using an ecological approach.Several environmental variables potentially influencing the onset of type 1 diabetes have been previously evaluated.However,the relationships between epidemiologic data and exposure to toxic airborne molecules are scarcely studied.METHODS We employed an ecological model to explore,in a wide time period(1990-2018),associations between type 1 diabetes incidence in 19 European countries(systematic literature review)and the nationwide production of five widely diffused air pollutants:particulate matter<10μm(PM10),nitrogen oxides(NO),non-methane volatile organic compounds(VOCs),sulphur oxide(SO2),and ammonia.RESULTS Data confirm a raising incidence of type 1 diabetes in 18 out of 19 explored countries.The average difference(last vs first report,all countries)was+6.9×100000/year,with values ranging from-1.4(Germany)to+16.6(Sweden)per 100000/year.Although the overall production of pollutants decreased progressively from 1990 to 2018,type 1 diabetes incidence was positively associated with the nationwide emissions of PM10,VOCs,and NO but not with those of SO2 and ammonia.Type 1 diabetes incidence was significantly higher in countries with high emissions than in those with low emissions of PM10(27.5±2.4 vs 14.6±2.4×100000 residents,respectively),VOCs(24.5±4.4 vs 13.2±1.7×100000 residents,respectively),and NO(26.6±3 vs 13.4±2.4×100000 residents,respectively),but not of SO2 or ammonia.CONCLUSION Evidence justify further studies to explore better links between long-term air quality and type 1 diabetes onset at the individual level,which should include exposures during pregnancy.In this respect,type 1 diabetes could be,at least in part,a preventable condition.Thus,primary prevention policies acting through a marked abatement of pollutant emissions might attenuate future type 1 diabetes incidence throughout Europe.

Emissions of C_2-C_(12) hydrocarbons in the Hsuehshan tunnel,Taiwan

The concentrations of 56 hydrocarbons from C2 to C12 were measured simultaneously in the southbound bore,the northbound bore and the exhaust air shafts of the Hsuehshan tunnel near Yilan,Taiwan for 12 days during 2007 and 2008.A total of 60 integrated air samples were collected using stainless steel canisters and analyzed using GC/FID and GC/MS.The five most abundant species in all samples were ethylene,acetylene,isopentane,propylene and toluene.The exit/entrance ratios of total non-methane hydrocarbons（NMHC） concentration were 7.8 and 4.8 for the southbound and northbound bores,respectively.Furthermore,the exhaust from the vertical shafts a？ects air quality in the neighborhood.The most abundant species of emission rate（ER） was toluene（21.93-42.89 mg/sec）,followed by isopentane,ethylene,propylene and 1-butene,with ER ranging from 2.50 to 9.31 mg/sec.The species in the three exhaust air shafts showed that the reactivities of these emissions are similar to those of vehicle emissions.Notably,the control of emissions in the vertical shafts of the vehicle tunnel will be important in the future.

Variation Characteristics of Ambient NMHCs at Shangdianzi and Lin’an Regional GAW Sites

In order to study the variation characteristics of concentration of the atmospheric non-methane hydrocarbons （NMHCs） in background area of China, the atmospheric concentrations of NMHCs were measured at Lin＇an （LA） regional GAW （Global Atmosphere Watch） Station （30°25＇N, 119°44＇E; 132.0 m ASL） and Shangdianzi （SDZ） regional GAW Station （40°19＇N, 117°07＇E; 286.5 m ASL） with the sorbent sorption/thermal desorption/gas chromatographic method. Totally 145 samples were collected during the period of October 2003 and July 2004. Among the 52 NMHC species of C2-C10 detected there were 26 alkanes, 17 alkenes, and 9 aromatics. The average concentrations of total NMHCs （TNMHCs） at LA and SDZ were （238.5±126.0） ×10^-9C and （278.7±185.5）×10^-9C, respectively. The results showed the ambient concentrations of TNMHCs at LA regional GAW Station increased notably over the last decade. The compositions of NMHCs at SDZ and LA were relatively similar. The proportions of alkanes, alkenes, and aromatics for SDZ and LA were in ranges of （27.3±4.0）%, （10.3±3.5）%, and （62.5±4.8）%, respectively, with features of vehicle exhaust emissions. The concentrations of NMHCs at the two sites showed obvious diurnal and seasonal variations. The TNMHC concentrations in October-November were high at the two sites, and relatively low in April and July. The diurnal variation patterns at the sites were different. The high TNMHC concentrations at SDZ normally appeared in evening and night, but appeared in morning at LA. The TNMHCs concentrations at the two sites were significantly influenced by the meteorological condition. The high TNMHC concentration associated with the local wind from the urban areas or traffic in upper reaches.