Effect of wildfire smoke exposure on the development of tuberculosis and mortality due to COVID-19

Project Summary Wildfires are currently growing in size, frequency, and severity in many places globally. Consequently, increasingly large populations are being exposed to high concentrations of air pollution from wildfire smoke. Wildfire smoke exposure has been linked to numerous adverse health outcomes, particularly non-communicable pulmonary conditions. There is growing evidence that pollutants present in wildfire smoke are also associated with human immune cell changes that increase susceptibility to infection with both viral and bacterial respiratory pathogens. However, relatively few studies have directly examined the relationship between wildfire smoke exposure and infectious respiratory diseases. Given the enormous, overlapping populations affected by both wildfire smoke and infectious respiratory diseases, better understanding the relationship between these phenomena may have important health consequences. The aim of the proposed research is to use large, individual-level data sources to establish robust evidence on the impact of wildfire smoke exposure for two leading infectious respiratory diseases that each impact millions of people globally each year, tuberculosis (TB) and COVID-19. Aim 1 uses a surveillance dataset of every case of and death due to COVID-19 in six western US States over a two-year period to assess whether exposure to wildfire smoke close in time to infection with COVID-19 is associated with increased mortality risk. Aims 2 and 3 investigate the relationship between wildfire smoke exposure and TB. Aim 2 uses a detailed dataset of close contacts to individuals with TB in Los Angeles County over a nine-year period to assess whether wildfire smoke exposure that occurs close in time to exposure to TB is associated with increased risk of Mycobacterium tuberculosis infection and subsequent development of TB. Aim 3 uses a national surveillance dataset of TB cases in Brazil over a five-year period to assess whether wildfire smoke exposure is temporally associated with increased TB diagnoses using a case-crossover design. Results from these studies will contribute among the first individual-level data regarding the risks of wildfire smoke exposure for TB and COVID-19 outcomes. The proposed research will improve understanding of how trends in wildfires may exacerbate the burden of infectious respiratory diseases. This mentored Ruth L. Kirschstein National Research Service Award proposes to provide the trainee, a doctoral student in epidemiology at Boston University, with rigorous interdisciplinary training in both environmental and infectious disease epidemiology that is supplemental to the standard PhD curriculum. Guided by a team of senior mentors with diverse backgrounds in both fields, the trainee will gain the necessary skills and expertise to launch an academic career as an independent researcher generating novel evidence at the nexus of environmental health and infectious diseases. A detailed training plan, in conjunction with the proposed mentored research, provides dedicated time for the trainee to obtain supplemental training in relevant epidemiologic methods and sources of environmental data, and hands-on experience building interdisciplinary, multi-institutional research partnerships.