TAIPEI (Taiwan News) — As Qiufen (秋分), the autumn equinox, begins today (Sept. 23), WeatherRisk Explore Inc. President Peng Chi-ming (彭啟明) has posted a forecast model projecting a large wave of pollution pouring into Taiwan over the next two days.

Peng said that air pollution from China has already begun to affect northern Taiwan and that some areas will potentially see a level of pollutants that is unhealthy for sensitive groups. Poor diffusion conditions in central and southern Taiwan combined with the photochemical reactions brought about by afternoon sunlight and pollution from China could cause air pollution to accumulate over the area.

A wave of northeasterly winds combined with a high-pressure system has brought pollutants to the east coast of China. The pollution is now wafting its way to northern and northeastern Taiwan, already triggering an orange alert in parts of Taoyuan City, Yunlin County, and Kaohsiung City to signal air that is unhealthy for sensitive groups.

Peng said that sensitive groups should be advised of potentially high concentrations of fine suspended particulates (PM2.5) in the air over the coming days. Those who are planning to spend extended periods of time outdoors are advised to monitor the Central Weather Bureau's (CWB's) Air Quality Index (AQI).

As diffusion conditions are poor for local pollutants in central and southern Taiwan, and as more arrives from China, much of Western Taiwan could see increased levels of air pollution. The CWB could issue orange alerts in more regions across the country later today and on Tuesday.

Autumn and Winter are characterized by stable weather and lead to poor pollution diffusion in central and southern Taiwan. Any source of air pollution, whether domestic and foreign, is more likely to accumulate during these seasons, said Peng.