Update: looks like the selling has stopped for now. NASDAQ OPTIONS MKT REOPENED FOR TRADING, SPOKESMAN SAYS
If one has no access to a market pricing service, perhaps the simplest and easiest way of testing if the market is down, is to check the NASDAQ market system status page. Usually, on down days, the NASDAQ just, well, breaks. As it did moments ago when it announced that trading in options with a symbol range A through M has been halted.