TAIPEI (Taiwan News) — Northeasterly monsoon winds are worsening air quality in southern Taiwan, with an orange alert indicating conditions are “unhealthy for sensitive groups” expected to persist through Thursday, according to the Ministry of Environment.

The Taiwan Air Quality Monitoring Network reported Tuesday that air quality levels in Tainan, Yunlin, Chiayi, Kaohsiung, and Pingtung have reached the orange alert level. The designation advises sensitive groups, including children, older adults, and people with heart or respiratory conditions, to limit outdoor activity, reduce physical exertion, or wear masks when outside.

Air quality in Hualien and Taitung was rated green, or “good,” on Tuesday, while most northern and central areas were listed as yellow, indicating “moderate” conditions.

Prevailing winds earlier this week moved in a northeasterly direction, carrying trace amounts of pollutants from overseas. As a result, western Taiwan, which lies on the leeward side, is more prone to pollutant accumulation, while eastern Taiwan, on the windward side, experiences better dispersion, per Liberty Times.

Northeasterly monsoon winds are expected to strengthen on Wednesday, bringing additional overseas pollutants that will affect Taiwan and its outlying islands. Early morning fog or low clouds may reduce visibility in central and southern Taiwan and the Matsu Islands, while cooler temperatures are forecast for northern and northeastern Taiwan.

As clouds and rain bands move eastward from southern China, increased moisture is expected to bring localized, brief showers to areas north of central Taiwan and the northeast. On Thursday, northeasterly monsoon winds are forecast to weaken, with daytime temperatures rising and air quality across Taiwan and its outlying islands expected to gradually improve.