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Despite its emerging significant public health concern, the presence of antibiotic resistance genes (ARGs) in urban air has not received significant attention. Here, we profiled relative abundances (as a fraction, normalized by 16S rRNA gene) of 30 ARG subtypes resistant to seven common classes of antibiotics, which are quinolones, β-lactams, macrolides, tetracyclines, sulfonamides, aminoglycosides, and vancomycins, in ambient total particulate matter (PM) using a novel protocol across 19 world cities. In addition, their longitudinal changes in PM2.5samples in Xi’an, China as an example were also studied. Geographically, the ARGs were detected to vary by nearly 100-fold in their abundances, for example, from 0.07 (Bandung, Indonesia) to 5.6 (San Francisco, USA). The β-lactam resistance gene blaTEMwas found to be most abundant, seconded by quinolone resistance gene qepA; and their corresponding relative abundances have increased by 178% and 26%, respectively, from 2004 to 2014 in Xi’an. Independent of cities, gene network analysis indicates that airborne ARGs were differentially contributed by bacterial taxa. Results here reveal that urban air is being polluted by ARGs, and different cities are challenged with varying health risks associated with airborne ARG exposure. This work highlights the threat of urban airborne transmission of ARGs and the need of redefining our current air quality standards in terms with public health.

In Northern Vietnam, smallscale cassava starch processing is conducted in densely populated craft villages, where processors face difficulties to expand their activities. Three different processing systems were studied among a cluster of three communes in the Red River Delta, producing up to 430 t of starch at 55 dry matter per day. The first system, type A, is a cylindrical rasper and a manual sieve, the second, type B, is a cylindrical rasper and stirringfiltering machine and the third, type C, used equipment for both the rasping and filtering stages. Moisture, starch, crude fibers and ash content analysis were carried out on samples collected from the ABC manufacturing processes to establish the mass balance of starch. Production capacity, water consumption, electrical requirements and capitallabor costs per tonne of starch 12 moisture were also reported. ABC manufacturing processes enabled 75 recovery of the starch present in fresh roots. No significant change was observed in the composition of starch. Upgrading from system A to B and subsequently to C resulted in an increase in the extraction capacities up to 0.9 t of peeled roots per hour, the extraction efficiencies during the extraction stage up to 93, and an increase in the water consumption and electrical power up to 21 m3and 55 kWh per tonne of starch, respectively. The highest amount of total solids carried in the wastewater was obtained with type C up to 17 of the dry weight of fresh roots, compared to 10 and 13 for type A and B, respectively. This may lead to a higher chemical oxygen demand COD and biological oxygen demand BOD in wastewater, which can result in more polluted wastewater than compared with the type A and B technologies. Upgrading the raspingextraction technologies also resulted in higher profits and reduction of labor per tonne of starch up to 18 US$ and 26 manhours respectively. The diagnosis proposed in this study can be applied in different contexts to recommend technological options by considering space, energy and capitallabor availabilities.