Wind speed
The first emission scenario, causing 2% of emissions, results from the production of materials. Studies of a precious metals refinery found that the mining and refining of metals releases a significant amount of nanoparticles into the air. Further analysis showed concentration levels of silver nanoparticles far higher than OSHA standards in the air despite operational ventilation. Wind speed can also cause nanoparticles generated in mining or related activities to spread further and have increased penetration power. A high wind speed can cause aerosolized particles to penetrate enclosures at a much higher rate than particles not exposed to wind.