Table 4. Assessment of respiratory protective equipment (RPE)
First author [ref.]DesignAgentType of RPEEffects of RPE
Muller-Wening [54]Laboratory challenge
Non-RCT study
Exposure: 1 h, not quantified
Organic farm allergensRPE with P2 filter: "Dustmaster" (n=21), "Airstream helmet" (n=4), "Airlite" (n=1)Suppression of symptoms in 11 out of 26, reduction in 15 out of 26, but 4 required inhaled bronchodilator
Reduction of the increase in airway resistance
Laoprasert [55]Laboratory challenge
RCT study with placebo
Exposure: 1 h, quantified
LatexLaminar flow HEPA–filtered helmetReduction of symptom score
Reduction of the decline in FEV1
Slovak [56]Workplace exposure
Non-controlled study
Exposure: 6 weeks, not-quantified
Laboratory animalsPowered helmet respirator with AS-23-3 filterWorsening of symptoms in 2 out of 8 (score not available)
Peak flow variation at work in 2 out of 8
Kongerud [57]Workplace exposure
RCT study
n=19 workers with nonsevere disease
Exposure: 2 weeks, not quantified
Aluminium pot roomAH60 Airsteam helmetReduction of symptom score in 10 out of 17 subjects (nonsignificant)
Improvement in the mean peak flow values
Taivainen [58]Workplace exposure
Non-RCT study
Exposure: 10 months, not quantified
FarmingPowered dust respirator helmet with P2 filterNo effect on respiratory symptoms with the exception of sputum, rhinitis symptoms, corticosteroid treatment, and number of sick leaves
Increase in morning peak flow and reduced daily peak flow variability
  • RCT: randomised controlled trial; HEPA: high-efficiency particulate arrest; FEV1: forced expiratory volume in 1 s.