Roadside particulate levels at 30 locations in the Kathmandu Valley, Nepal

Roadside particulate levels (PM10) at 30 locations throughout the Kathmandu Valley, Nepal are reported. There were seven sampling cycles from January to December 1999. PM10 levels ranged between 1000 and 6000 mug/m(3) for 1-h sampling. There was no consistent trend in PM10 levels with respect to monitoring cycle, average precipitation or wind speed. There is no WHO guideline for PM10 (no safe exposure threshold), but the EPA 24-h standard is 150 mug/m(3). The major sources of roadside PM10 include dust resuspension from vehicular movement and human activity, and particulate emissions from old vehicles. Other sources of PM10 in the valley include cement and brick factories. Studies are currently being conducted to determine the lead content of PM10 from roadside samples. Additional studies are warranted to assess the potential adverse human health effects of acute or chronic exposure to high particulate levels reported in this study.