Jun 19, 2013

of 3-hour psi 290 (very unhealthy)

The three-hour Pollutant Standards Index (PSI) reading soared to 290 at 9pm on Wednesday, setting a new all-time high and almost hitting hazardous levels of 301 and above. The last reading clocked at 8pm was 190, which was still in the "unhealthy" range. An hour later, however, the reading jumped 100 points to 290, entering the "very unhealthy" range.