TAIPEI (Taiwan News) — Taipei is advising those in the city planning to go outside on New Year's Eve and New Year's Day to wear face masks.

Taipei City’s environment bureau said the air quality in Taiwan’s north is expected to deteriorate on Sunday afternoon (Dec. 31), per CNA. The poor air quality is expected to remain until Monday morning.

The city has implemented an “orange alert” for air quality and recommended the public wear masks when going outdoors. An orange alert indicates the presence of “fine inhalable particles” in the air, at 2.5 micrometers in size.

The city also said the elderly, the immunocompromised, young children, and those with cardiovascular disease should avoid going outdoors as much as possible, and wear masks if they do.