SHiNE Pharmacy chief pharmacist Christina Wong said N95 and KN95 respirators offer better protection from fine particles than loose-fitting surgical masks. Song Plaza Caring Pharmacy pharmacist Wendy Tsai also recommended KF94 masks, which are available in adult and children’s sizes.

Both pharmacists stressed that fit matters. Parents were advised to keep young children indoors when air quality is poor, while older people and those with asthma or chronic lung conditions should take extra care outdoors.

For people who must go outdoors, the useful detail is fit: a well-sealed N95, KN95 or KF94 offers better particle protection than a loose face covering. Children, older people and anyone with asthma or heart or lung conditions should keep outdoor exertion down while the reading remains unhealthy.