Air in the breathing zone (about 30cm from the mouth) was sampled for each trip to measure PM concentrations.

If [sprays are] used, people can protect themselves by opening Windows, avoiding the application near the breathing zone, and by using masks or other types of personal respiratory protection.

The possibility of suck-back of fume cupboard exhaust gases into building air intakes, open Windows or the breathing zone of people working on the roof or in other buildings should be investigated.