Traffic-induced nanoparticle emissions and associated respiratory risk analysis using measurements conducted in a roadside environment

Air quality is a major concern for healthy living as particles present in air are directly associated with human health, especially in urban regions that are more vulnerable to different types of atmospheric pollutants. In this study, for the first time, the concentration of atmospheric nanoparticles in an urban roadside environment are analysed, and the deposition of these nanoparticles in human respiratory tract are quantified using Multiple-path particle dosimetry model for different age groups over Delhi. The measured seasonal mean nanoparticle concentration ranges from 24,000 to 41,000 particles cm^− 3. The seasonal sequence of deposition of nanoparticles is winter > monsoon > summer > autumn > spring. The deposition of nanoparticle in adults is 30 to 40% higher than in children and infants, and further, the deposition is higher in the alveolar region than in the bronchiole and trachea regions. About 90% of the particles get deposited in the alveolar regions, 6 to 8% in the bronchiole region, and 2% in the trachea region. The estimated deposition of nanoparticles for an individual working 8 h a day in the near road conditions is 338 µg/year in Delhi. The deposition increases almost linearly as a function of time, and is 3 times higher (1016 µg/year) for a person residing near the road throughout the day (24 h). The deposition fraction of particles ranges between 0.05 and 0.10 µg/day in the alveolar region, < 0.05 µg/day in the bronchiole region, and lies between 0.02 and 0.04 µg/day in the trachea. The nanoparticles deposited in the respiratory system can lead to the development of various diseases such as asthma, chronic obstructive pulmonary disease, and can lead to carcinogenicity. The new insights from the study gained on the deposition of nanoparticles in humans residing near roadside conditions are crucial to estimate the human health risk potential, and to formulate mitigation measures for exposure reduction which can result in a better and sustainable future.