2.2. Second Hand Smoke

Side-stream second-hand tobacco smoke was generated by allowing a lit cigarette to burn while placed inside a 2 m³ exposure chamber. Respirable particulate matter was collected from the chamber air on to 37 mm polycarbonate filters placed inside a Higgins Dewell type cyclone with air drawn through it at 2.2 L/min by a Casella Apex pump [18]. Particulate matter was removed from the filters by sonication in distilled water (25 mL) for thirty minutes. After sonication the filters were left to soak overnight before being removed and dried. The particulate solution was then freeze dried, weighed and a stock solution of known concentration prepared. The particulate solution was added to growth media.