Effect Of Using Ventilation Hood During Cooking On Exposure To Fine Particulate Matter And The Potential Benefits In Indicators Of Platelet Activation

Objective:Epidemiological evidence suggested that using ventilation facilities during cooking was associated with alleviated mortality risk from household air pollution exposure.However,data from community-based trials to quantitatively evaluate the impact of ventilation intervention on individual exposure to indoor air pollution and the possible health benefits are lacking.To determine whether use of ventilation hood during cooking could reduce exposure to fine particulate matter(PM_2.5),and further alleviate platelet activation.Methods:We conducted a parallel controlled intervention study of using ventilation hood during cooking with clustered randomization at five adjacent,economically undeveloped villages in Yunnan province of southwest China.We recruited a total of 175villagers who were aged 18 years or older,without major disabilities and having no intention of leaving home within one year.During recruitment,we encouraged cooking members of each family to participate,and enrolled those not regularly cooking as well,with the assumption that cooking-generated air pollution would eventually expose the whole family.The unit for randomization was defined as household initially,and then increased to the village level among four of the five villages where the residents reacted particularly unfavorably when finding about the indiscriminating treatment between intervention and control groups.Four villages were randomly assigned to either the intervention（n=2;84participants）or the control group（n=2;32 participants）,while in the remaining village,31participants from 28 households were assigned to the intervention group,and the 28participants from 24 households to the control group.We conducted 24-hour personal PM_2.5exposure monitoring,physical examination and questionnaire survey at baseline during March 6^th to April 8^th,2019 and follow-up visit during November 6^th to December 2^nd,2019,respectively,right before and after the rainy season from May to October.Results:In total,151（86.3%）of 175 participants enrolled at baseline completed the trial.The meta-analysis of the effects from intervention within the participants randomized in unit of either village or household revealed that the change in the average and 95^th percentile personal PM_2.5 exposure levels were significantly lower in the intervention group compared with the control group(between-group difference:-26.20%[P=0.041,P_{heterogeneity}=0.530]and-44.64%[P=0.027,P_{heterogeneity}=0.782],respectively).We also found significant reductions in indicators of platelet activation by intervention,including mean platelet volume(MPV;4.30%reduction[P=0.001,P_{heterogeneity}=0.133]),platelet distribution width(PDW;4.88%reduction[P=0.060 P_{heterogeneity}=0.115]),platelet-large cell ratio(P-LCR;11.04%reduction[P=0.002P_{heterogeneity}=0.163]).Among solid fuel-using cooking participants,greater reduction in average(-32.95%[P=0.041,P_{heterogeneity}=0.417])and P⁹⁵(-58.11%[P=0.011,P_{heterogeneity}=0.583])PM_2.5 exposure level was observed.Favourable changes were also found in indicators of platelet activation(MPV:4.88%reduction[P=0.014,P_{heterogeneity}=0.780],PDW:6.67%reduction[P=0.067,P_{heterogeneity}=0.688],P-LCR:13.32%reduction[P=0.009,P_{heterogeneity}=0.699]).Considering that balance was not actually achieved between the intervention and control groups in this study,we performed additional sensitivity analysis further adjusting for the imbalanced covariates,and the results remained unchanged.Similar results were also shown in the per-protocol analysis.In addition,we observed that among baseline population per 10μg/m³ reduction in the 95^th percentile personal 24h personal PM_2.5exposure was associated with 0.17%decrease in PCT（P=0.048）.Conclusions:This study provided the first line of trial evidence that use of ventilation hood during cooking could effectively reduce personal PM_2.5 exposure,and further ameliorate platelet activation after long-term intervention.Our findings supported the prospect of promoting use of ventilation hood to cost-effectively reduce cooking-related PM_2.5exposure and improve health,particularly in economically deprived areas.