The Philippine peso and the Malaysian ringgit fell as interbank speculators added dollar holdings, while the Singapore dollar eased after an unexpected fall in industrial output.
Offshore funds sold the won, although the South Korean currency pared losses on demand from exporters for settlements.
Asian shares, the euro and commodities slid on concerns over Spain's hesitancy to request a bailout even as protests there turned violent.
"At this juncture, we are watchful over the potential for dollar/Asia currencies to explore higher ground given that a reality check seems to be enveloping the broader market in general as the euro zone and global growth concerns re-surface," said Emmanuel Ng, a foreign exchange strategist at OCBC Bank in Singapore.
Most emerging Asian currencies have risen so far this month as the Federal Reserve and the Bank of Japan eased monetary policies in hopes of spurring growth, while European policymakers took steps to tackle the now three-year old debt crisis.
But their gains were checked as investors shifted their focus to the sluggish global economy, which analysts and dealers said would boost chances of intervention by Asian authorities to slow down their currency appreciation and to protect their export competitiveness.
Some doubted if emerging Asia will enjoy much more inflows from a third round of quantitative easing by the Fed, while a Fed official warned that the easing may not work.
"The impact of QE3 on capital account inflows into NJA is arguably more difficult to estimate," said Barclays in a note, referring to non-Japan Asia.
Inflows to emerging markets have been modest year-to-date partly due to investors' expectations of modest total returns in the face of central bank intervention, relatively low yields and concerns about Chinese economic growth, it added.
Philadelphia Fed President Charles Plosser said on Tuesday that the Fed's latest stimulus will not do much to boost economic growth or lower unemployment and raise the risk of long-term inflation.
PHILIPPINE PESO
The Philippine peso weakened past a support line at 41.80 per dollar as interbank speculators covered dollar-short positions with some of them adding long bets.
A European bank dealer said the peso may head to 42.00 with global risk appetite dented, but he would the local unit around that level.
"The 42.00 is a great level to short dollars. Spain will eventually seek a bailout," said the dealer in Manila.
RINGGIT
The ringgit fell as traders scrambled for dollars to cover short positions in the greenback, while the euro's slide and Malaysian exporters took away bids for the local currency.
The Malaysian unit weakened 0.4 percent to 3.0820 per dollar, a notch firmer than 3.0835, the 50.0 percent Fibonacci retracement of its August-September appreciation.
The local currency may head to 3.0949, the 61.8 percent retracement level if it ends the day weaker than the 50.0 percent level.
But some traders were looking to buy the ringgit on dips.
SINGAPORE DOLLAR
The Singapore dollar tested 1.2322 to the US dollar, the 38.2 percent retracement of its appreciation between late August and mid-September, as industrial output data raised fears the trade-dependent economy will slip into recession this quarter.
The city-state's industrial production in August fell 2.2 percent from a year earlier, far missing a forecast of 1.1 percent growth, data showed earlier.
If the local currency closes to session softer than the 38.2 percent retracement, it may weaken to 1.2367, the 50.0 percent retracement.
WON
The won eased as offshore funds sold the South Korean currency with concerns over Spain hurting risk sentiment, while local importers bought dollars for payments.
But South Korean exporters took the slide as chances to buy it on dips for month-end settlements, limiting the local currency's downside, dealers said.