When the air is stagnant, pollution from fireworks may reach dangerous levels. On January 1, 2003, stagnant air triggered a "level red" exposure to fine particles that began during the evening hours as individuals set off fireworks in celebration of New Year's day. The Channelview monitor recorded pollution levels over 200 micrograms per cubic meter, and averaged about 74 ug/m³ for the day. (To put it in perspective, during the several days after the World Trade Center was destroyed, peak levels of pollution were measured in the 100-150 ug/m³ range, with average levels in the range of 25 ug/m³.) Similar episodes were noted in other cities that were experiencing similar weather patterns. There were no warnings, nor media coverage, of the pollution event. It was only discussed months later as an intellectual curiosity at a national air pollution conference. It has turned out to be the single worst episode for fine particle air pollution in many years.