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Coal is used widely for domestic cooking in many regions of India, which contributes significantly to the particulate matter (PM < 2.5 μm) and CO levels in ambient and indoor air. Modeling and inventorization require the use of emission factors (EFs) for cookstoves, which are specific to fuel type and cookstove design. These are usually not available or are available for emissions under steady state combustion conditions following some protocols that are end-use-specific. In this study, two types of cookstoves are deployed, and PM < 2.5 μm and CO emissions are measured for a combustion cycle that includes an initial ignition stage, a flaming stage, and a smoldering stage. EFs are estimated for PM < 2.5 μm and CO for each of these stages of the combustion cycle and indicate a 5−9-fold increase for PM < 2.5 μm when emissions from the ignition stage are included. Elemental carbon and organic carbon analyses are presented for PM < 2.5 μm using two protocols, namely, IMPROVE_A and DIN-19539. The EFs developed for the complete combustion cycle may be used to better represent the impact of coal cookstoves on the ambient air quality and for a more realistic assessment of health effects for exposure in kitchens.

Due to the airborne nature of viral particles, adequate ventilation has been identified as one suitable mitigation strategy for reducing their transmission. While ‘dilution of air by opening the window’ has been prescribed by national and international health agencies, unintended detrimental consequences might result in many developing countries with high ambient air pollution. In the present study, PM 2.5 exposure concentration and probability of mortality due to PM 2.5 in different scenarios were assessed. A COVID airborne infection risk estimator was used to estimate the probability of infection by aerosol transmission in various commuter micro-environments: (a) air conditioned (AC) taxi (b) non-AC taxi (c) bus and (d) autorickshaw. The following were the estimated exposure concentrations in the four types of vehicles during pre-lockdown, during lockdown, and lost-lockdown: AC taxi cars (17.16 μg/m 3 , 4.52 μg/m 3 , and 25.09 μg/m 3 ); non-AC taxis: (28.74 μg/m 3 , 7.56 μg/m 3 , 42.01 μg/m 3 ); buses (21.79 μg/m 3 , 5.73 μg/m 3 , 31.86 μg/m 3 ) autorickshaws (51.30 μg/m 3 , 3.50 μg/m 3 , 75 μg/m 3 ). Post-lockdown, the probability of mortality due to PM 2.5 was highest for autorickshaws (5.67 x 10 -3 ), followed by non-AC taxis (2.07 x 10 -3 ), buses (1.39 x 10 -3 ), and AC taxis (1.02 x 10 -3 ). This order of risk is inverted for the probability of infection by SARS-COV-2, with the highest for AC taxis (6.10 x 10 -2 ), followed by non-AC taxis (1.71 x 10 -2 ), buses (1.42 x 10 -2 ), and the lowest risk in autorickshaws (1.99 x 10 -4 ). The findings of the present study suggest that vehicles with higher ventilation or air changes per hour (ACH) should be preferred over other modes of transport during COVID-19 pandemic.

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