The amount of engineered nanoparticles is increasing at a rapid rate and more concerns are being raised about the occupational health and safety of nanoparticles in the workplace, and implications of nanotechnology on the environment and living systems. At the same time, diesel engine emissions are one of the serious air pollution sources in urban area. Ultrafine particles on the road can result in harmful effects on the health of drivers and passengers. Research on characterization, exposure measurement and control is needed to address the environmental, health and safety issues of nanoscale particles. We present results of our studies on airborne particles in workplaces and on the road.