Particle and Carbon Dioxide Concentration Levels in a Surgical Room Conditioned with a Window/Wall Air-conditioning System.

One of the most important functions of air conditioning systems in operating rooms is to protect occupants against pathogenic agents transported by air. This protection is done by simultaneously controlling the air distribution, temperature, humidity, filtration and infiltration from other areas etc. Due to their low price, simple installation, operation and maintenance, window/wall air conditioning system have largely been used in operating rooms in Brazil, even if these types of equipment only recirculate the air inside the room without appropriate filtration and renovation with outdoor air. In this context, this work aims to analyse the performance of the window/wall air conditioning systems on indoor air ventilation in operating rooms by measuring particle number concentrations and carbon dioxide concentrations during different surgical procedures, in a single surgical room and in the nearby areas (corridor) for two cases: single surgery and two subsequent surgeries. In addition, the efficiency of the analysed air conditioning system was evaluated by comparing the ventilation level calculated in the surgical room with the ventilation required in order to maintain the carbon dioxide concentration within acceptable levels. The results showed that this type of air conditioning system is not appropriate for use in operating rooms since it cannot provide an adequate level of ventilation. The CO2 concentrations during surgeries, in fact, significantly exceeded acceptable values and a simultaneous increase in particle number concentration was observed. The results also showed that there is a high risk of contamination between subsequent surgeries in the same surgical room, due to residues of contaminants transported by the particles emitted during the surgeries that were not removed from the operating room by the air conditioning system. The particle number concentration measured in the second surgery, in fact, was approximately six times higher than in the first surgery.

Sudden temperature changes and respiratory symptoms--an experimental approach.

BACKGROUND: Exposure to air-conditioning systems and allergic phenotypes are consistent risk factors to develop indoor air quality (IAQ) respiratory complaints. The aim of this study was to compare the role of allergic rhinitis on respiratory complaints in individuals exposed to sudden temperature changes. METHODS: To address this question, a case-control challenge study was performed in a laboratory of thermal comfort evaluation with twin isolated chambers set at 14 degrees C/57.2 degrees F (cold) and 26 degrees C/78.8 degrees F (hot) temperatures. A groups of 32 patients with persistent allergic rhinitis (rhinitis group) and 16 control subjects (control group) were exposed for 30 minutes, three times alternately in the chambers. Symptoms were reported using an analog visual scale and nasal and pulmonary peak flow measurements were taken during baseline at hot and cold temperatures and after the challenge. RESULTS: The rhinitis group reported increased itching and stinging eyes when compared with the baseline during exposure to hot and cold temperatures and they also reported increased breathlessness during hot air exposure. In addition, there was a significant decrease in expiratory flow rates in this group during exposure to hot and cold temperatures that persisted for 24 hours after challenge. CONCLUSION: This study suggests that individuals with allergic rhinitis have a lower threshold than controls to develop respiratory and ocular symptoms after air-conditioning-induced sudden temperature changes.

The role of allergic rhinitis in nasal responses to sudden temperature changes.

BACKGROUND: Air conditioning-induced rhinitis in allergic individuals is a common epidemiologic finding, but its physiopathology is still controversial. The aim of this study was to describe and compare the effects of experimental air conditioning temperature changes on the nasal mucosa of individuals with persistent allergic rhinitis compared with a control group. METHODS: A case-control challenge study was performed in a laboratory of thermal comfort with experimental twin challenge chambers set at a 12 degrees C difference in temperature. A group of 32 patients with persistent allergic rhinitis and a group of 16 control subjects were exposed for 30 minutes, 3 times alternately in each chamber. Nasal symptom scores were recorded and nasal samples collected before, immediately after, and 24 and 48 hours after the challenge. RESULTS: The rhinitis group showed a higher symptom score, epithelial shedding, percentage of eosinophils, total inflammatory cells, leukotriene C(4), eosinophil cationic protein, albumin, and tryptase levels compared with controls. There was also a significant increase in symptom score, total cells recovered, percentage of eosinophils, epithelial shedding, albumin, myeloperoxidase, and soluble intercellular adhesion molecule 1 in both groups compared with baseline levels. CONCLUSION: Sudden temperature changes led to a more pronounced inflammatory nasal response in the rhinitis group with the recruitment and activation of eosinophils. CLINICAL IMPLICATIONS: Persistent allergic rhinitis is a risk factor for developing sudden temperature change-related rhinitis even in the absence of allergen exposure.