Carter, EllisonNorris, ChristinaDionisio, Kathie L.Balakrishnan, KalpanaCheckley, WilliamClark, Maggie L.Ghosh, SantuJack, Darby W.Kinney, Patrick L.Marshall, Julian D.Naeher, Luke P.Peel, Jennifer L.Sambandam, SankarSchauer, James J.Smith, Kirk R.Wylie, BlairBaumgartner, Jill2018-01-182017Carter, E., C. Norris, K. L. Dionisio, K. Balakrishnan, W. Checkley, M. L. Clark, S. Ghosh, et al. 2017. “Assessing Exposure to Household Air Pollution: A Systematic Review and Pooled Analysis of Carbon Monoxide as a Surrogate Measure of Particulate Matter.” Environmental Health Perspectives 125 (7): 076002. doi:10.1289/EHP767. http://dx.doi.org/10.1289/EHP767.http://nrs.harvard.edu/urn-3:HUL.InstRepos:34651948Background: Household air pollution from solid fuel burning is a leading contributor to disease burden globally. Fine particulate matter (PM2.5) is thought to be responsible for many of these health impacts. A co-pollutant, carbon monoxide (CO) has been widely used as a surrogate measure of PM2.5 in studies of household air pollution. Objective: The goal was to evaluate the validity of exposure to CO as a surrogate of exposure to PM2.5 in studies of household air pollution and the consistency of the PM2.5–CO relationship across different study settings and conditions. Methods: We conducted a systematic review of studies with exposure and/or cooking area PM2.5 and CO measurements and assembled 2,048 PM2.5 and CO measurements from a subset of studies (18 cooking area studies and 9 personal exposure studies) retained in the systematic review. We conducted pooled multivariate analyses of PM2.5–CO associations, evaluating fuels, urbanicity, season, study, and CO methods as covariates and effect modifiers. Results: We retained 61 of 70 studies for review, representing 27 countries. Reported PM2.5–CO correlations (r) were lower for personal exposure (range: 0.22–0.97; median=0.57) than for cooking areas (range: 0.10–0.96; median=0.71). In the pooled analyses of personal exposure and cooking area concentrations, the variation in ln(CO) explained 13% and 48% of the variation in ln(PM2.5), respectively. Conclusions: Our results suggest that exposure to CO is not a consistently valid surrogate measure of exposure to PM2.5. Studies measuring CO exposure as a surrogate measure of PM exposure should conduct local validation studies for different stove/fuel types and seasons. https://doi.org/10.1289/EHP767en-USJournal Article2018-01-1810.1289/EHP767