Rationale and Design of a Study to Test the Effect of Personal Protective Aids on Hypertension and Diabetes in People Living With High Levels of Air Pollution—Study Protocol

Abstract

Air pollution is the largest environmental cause of disease and premature death in the world today, disproportionally affecting low- and middle-income countries (LMIC) such as India. Studies have shown that exposure to particulate matter <2.5 μm (PM2.5) can contribute to cardiovascular disease and increase mortality. We hypothesise that the use of personal protective aids (home indoor air purifiers/N95 masks) can decrease systolic blood pressure (SBP) in people with hypertension and decrease fasting blood glucose levels (FBG) in those with diabetes. This is a prospective randomised crossover study in Dalkhola, India-an area of high ambient PM2.5 levels. Participants between 18-70 years of age with hypertension (n=128) and diabetes (n=33) will be invited to participate in the study. They will be randomised to either an intervention or control arm for 4 weeks, after which they will cross over to the other arm following a 2-week washout period. The intervention will consist of using an indoor air purifier at night and N95 mask when outdoors. The control period will involve using an identical air purifier and N95 mask with the filter removed (sham filtration). Participants and outcome assessors will be blinded to study arm assignment. The primary outcome of the study is the absolute reduction in SBP among people with hypertension and absolute reduction in FBG among people with diabetes. This is the first randomised controlled trial to evaluate the use of personal protective aids as a therapeutic measure in people with hypertension and diabetes exposed to high levels of PM2.5. Given the high burden of air pollution in LMIC, there is an urgent need for adaptation measures targeting people at high risk for mortality from this exposure. The results of our study will demonstrate whether personal protective aids can be a viable adaptation measure for people living with hypertension and diabetes in areas with a high burden of air pollution. This is clinicaltrials.gov Identifier: NCT04854187.