Most of these pyrethroids have been detected in house dust from several different studies . The majority of these studies were conducted with the general population and two were conducted with farm working communities; however there was little difference between pyrethroid concentrations in the house dust from the two types of populations. We observed lower detection frequencies and/or lower median concentrations of cis– and trans-permethrin than many of these studies . We also observed lower or comparable detection frequencies and median concentrations of cypermethrin in our study as compared to others . Deltamethrin and esfenvalerate were detected more frequently in the house dust from our study than in any other . Only two other studies looked at resmethrin in house dust, and neither was able to find detectable levels compared to the 29% detection in our study. The differences in detection frequencies in our study as compared to these other studies may be the result of different LODs. Additionally, our study population was restricted to only those families with young children, potentially causing differences in pesticide use practices when compared to a more diverse population containing people of differing ages, marital statuses, and living arrangements. Also, because we weighted our sample selection to those households whose participants already showed exposure to pyrethroids, a true random sampling from our study population may have exhibited lower detection frequencies than what has been reported here. We also did not observe the seemingly extreme outliers or maximum concentrations several orders of magnitude over the median concentration that some of the other studies reported. This may be due to our study population being better trained in pesticide use practices and precautions from work in agriculture than urban dwellers. We wanted to examine the potential reasons for the lack of correlations with the questionnaire data.
We used data from the main MICASA study questions on pesticide use, which were asked of the full cohort of 436 households in two interviews,hemp drying racks the first conducted from January 2006 to May 2007 and the second from February 2009 to June 2010. The consistency of responses to these pesticide use questions between the men and women from the same household was assessed and within-household levels of agreement were moderately high. Use was reported by both the man and the woman in 44% of the households in which either the man or the woman reported using outdoor pesticide sprays during the first interview. Assuming pesticides were actually applied if reported by either the man or the woman, asking only the man or the woman would misclassify many of the households that used pesticides as non-users, which may be partially responsible for the lack of correlation. Temporal comparisons from the same participant between the two interviews conducted approximately 3 years apart were also made. A larger fraction of the population reported using pesticides at the second interview than at the first interview, with only between 5.6 and 6.7% of individuals reporting use for both time periods. The low levels of agreement could be due either to actual changes in use patterns or due to differences in reporting and may also be partially responsible for the lack of correlation between questionnaire responses and house dust concentrations. Many previous studies have reported that residential pesticide use questions were ineffective at identifying exposure levels . We also saw a lack of consistency in the relationships between questionnaire data and measured levels of pyrethroids in the house dust . There was a positive correlation with reported outdoor pesticide use and pyrethroid levels in the house dust. However there was no relationship with indoor pesticide use. We found a slightly negative correlation with outdoor traps and levels of indoor pyrethroids, suggesting that families that use traps to reduce their pest problems use less pesticide in their homes.
A possible reason for the lack of correlations between reported pesticide use and pyrethroid levels found in the home is that the questionnaire asked about any pesticide products used for insect control, while we only measured five specific pyrethroid compounds. There are also likely to be large discrepancies in the amount of pesticide applied, as well as cleaning practices between participants. This information was not accounted for in our questionnaire. The most promising predictor of exposure was the pesticide inventory. There was a significant correlation between the pesticide inventory and the sum of pyrethroid concentrations found in the house dust. With traditional questionnaires, it is often difficult for participants to accurately recall pesticide use. The pesticide inventory on the other hand is relatively easy data to collect, requiring only a few minutes time for the interviewer to note the pesticide products present in the participant’s homes. Although neither method gives information on what, or the concentrations of, specific pesticides that may be found in the physical samples from the home, the pesticide inventory may be a more useful tool to predict possible pesticide exposure than the traditional participant recall. This study has many limitations. Data from households with higher levels of dust or whose children had higher pyrethroid metabolite levels in the urine were more likely to be analyzed, which can be expected to lead to a positive bias in our estimates of household pyrethroid levels. Our small sample size limited the statistical power and may have prevented us from observing statistically significant correlations in our data. Additionally, as mentioned above, there was a lack of consistent reporting of pesticide applications between husband and wife. In 2009, 1.3 billion people lacked access to electricity at home . At night, households with no access to electricity make do mostly with candles or kerosene lamps to satisfy their illumination needs. These sources of light provide poor illumination and, more importantly, emit high amounts of pollutants harmful for human health. In fact, indoor air pollution is the third leading risk factor for global disease burden, after high blood pressure and smoking .2 Given the stylized fact that lighting is one of the first uses of electricity in newly electrified areas , electrification is expected to decrease IAP levels by replacing traditional source of lighting, like kerosene, candles, and wood sticks.
These reductions and their potential health effects are often argued to be one of the main benefits of electrification, but there is no solid empirical evidence to date. Our paper contributes to filling this gap by providing the first experimental estimates of the relationship between household electrification and indoor air pollution. To answer this key question we collected,industrial rolling racks within the frame of a clean experimental design, a uniquely rich dataset that pairs minute-by-minute fine particulate matter concentration with detailed data on household members’ time allocation.The reductions in overnight PM2.5 concentration result in large and significant falls in acute respiratory infections among children under 6. Depending on the exact specification voucher recipients report 37 to 44% lower incidence of ARI in the four weeks preceding the survey than non-recipients. To assess further health implications of the observed reductions in PM2.5 concentration among the population over 6, in section 6.1 we use data from the time allocation module to estimate the change in daily exposure to PM2.5. The resulting reductions in exposure to PM2.5 are large but unequally distributed among household members. Adult males benefit the most, with 59% lower exposure. Since adult females are still exposed to high PM2.5 concentrations while cooking, they benefit the least, with reductions in exposure of 33%. The figures for children are 46% and 39% . The dose response function recently developed by Pope III et al. based on first and second-hand tobacco smoking associates the figures we find with large reductions in the relative risk of lung cancer, 25% for adult females, 33% adult males, with the respective figures for children falling 25% and from 30% . Although the composition of PM2.5 generated by kerosene combustion is not the same as the one generated by cigarette smoking, the current scientific evidence cannot reject that their health effects are similar. The mechanism behind the PM2.5 reductions in our study setting is a substitution away from kerosene lighting. Electrification caused large reductions in kerosene expenditures, while changes in other traditional lighting sources like candles are small in magnitude and not statistically significant. We find no evidence of changes in cooking practices either. The reduction in kerosene use has important health implications, because although kerosene is usually considered a cleaner alternative to biomass, emissions from kerosene-burning devices are considered extremely harmful for human health. Aside from PM2.5, kerosene emissions include carbon monoxide , nitric oxides , and sulfur dioxide . These pollutants can impair lung function and increase infectious illness, asthma, and cancer risks Lam et al. . The reduction in kerosene use also has important environmental consequences, since kerosene lighting is responsible for 7 percent of annual black carbon emissions globally . The reductions in PM2.5 concentration found in this study are not necessarily obvious ex-ante for four reasons. First, since households continue to use fuelwood forcooking, and woodsmoke produces higher IAP concentration than lighting fuels, the resulting reductions in IAP may have been small and thus irrelevant for policy. In fact, given that there is still scarce evidence in the specialized literature, the evidence of a strong, positive relationship between kerosene use and PM2.5 concentration in a sample in which 70% of households rely on fuel wood for cooking is a contribution to the environmental health literature.Second, it may be the case that only the heaviest kerosene users experience significant reductions, and thus the average reduction may just be an illusion.
We explore this issue and find even though the highest polluters indeed get the highest gains, 80% of households experienced significant reductions in overnight PM2.5 concentration. Third, voucher recipients may have not adopted electricity at a high enough rate, thus the relationship between receiving a voucher and connecting to the grid may be too weak to reflect in IAP measurements. Fourth, households may be effective in dealing with IAP from lighting sources.The study closest to ours is Bernard and Torero , in which the authors implemented a RED to study the effects of electrification in Ethiopia. We build on their work with four main differences. First, our main outcome of interest is PM2.5, which is not measured in their study. Second, our design allows to control for externalities in adoption of electric connections, which due to characteristics of the Ethiopian electrification program is not possible in their study. Third, our study allows to analyze dynamic effects of household electrification, since it includes a baseline and three follow-up follow-up survey.Our findings differ qualitatively from the typical findings in the literature on improved cook stoves in two dimensions. First, the effects found in field studies on improved cook stoves are null or small, especially when compared to the effects expected from laboratory or controlled field studies.The second dimension is that unlike the cook stove literature , the reductions in PM2.5 observed in our sample are steady over time. The time resilience of the effects we find strengthens the link between household electrification and human health discussed in the preceding paragraphs. The remainder of this document is organized as follows. Section 2 presents the study setting and discusses the data. Section 3 describes the conceptual framework that guides our study. Section 4 presents the econometric approach. We discuss the main results in section 5. In section 6 we combine the findings on PM2.5 concentration with time-use data to infer PM2.5 exposure and health implications. Section 7 presents a note on the profitability of replicating our by a private agent, and section 8 concludes. The study takes place during a recent grid extension and intensification program in northern El Salvador, designed to be rolled-out in three phases according to construction costs and accessibility. In this program, the El Salvadorian government covered all the installation costs up to the electric meter, and households had to pay for their internal wiring and a connection fee . The fee for the safety certification is of around US$ 100. It is non-trivial for a household, amounting to roughly 20% of annual per capita income in our sample.