We showed a higher percentage of neutrophils in the hospital and university groups than in the control and a decreased percentage of macrophages in the housekeeper and control groups than in the hospital and university. The percentage of lymphocytes increased in the university, hospital, housekeeper and control groups than in the hospital and university. A lower percentage of eosinophils was observed in the housekeeper group than in the hospital group among the workers with up to a year of cleaning service experience.
Our results reinforce those of previous studies in which cleaning activities were associated with work-related asthma, as well as studies that found an excess risk of asthma among cleaners .
As exemplified in a study on the inflammatory process in the airways of patients with allergic and non-allergic asthma, eosinophils play an important role in the allergic inflammatory process. In the airways, inflammation is the result of complex interactions between inhaled allergens, immune cells and structural cells, such as epithelial cells, endothelial cells and fibroblasts. These interactions are mediated through cell-cell contacts and the release of several mediators, such as cytokines, chemokines and neuropeptides. T lymphocytes may also have a central role in the initiation of the allergic immune response, besides contributing to the chronic airway inflammatory response, airway remodeling and respiratory symptoms . Neutrophils have also an important role in inflammation associated with asthma, including in the severe asthma phenotype where neutrophilic inflammation predominates .
The incidence of occupational respiratory diseases is underestimated both by the difficulty of diagnostic confirmation and by the reluctance of the worker who often does not seek medical care to confirm the diagnosis for fear of losing his or her job. Even so, the growing increase observed in the incidence of occupational diseases has drawn increasing health-related attention to the work environment .
Symptomatology in work-related respiratory disease is an extremely important factor to be considered by health professionals . Our findings revealed that major complaints such as wheezing, chest tightness, shortness of breath, coughing, sneezing, runny nose and rhinitis were present only in the cleaning worker groups. It should be noted that water-soluble cleaning products have the capacity to irritate the upper airways .
Our study also revealed that the prevalence of asthma was higher, not only among hospital employees or housekeepers but also among workers from all cleaning groups, showing that professional cleaning activities could be related to work-related asthma, since no professional in the control group was identified as having asthma. These results are consistent with those of many other studies .
Jaakkola et al.  evaluated the relationship between occupation and the risk of developing asthma in adulthood, classifying occupations according to the potential exposure to inhalants that cause asthma. Of the predominantly male occupations, work in areas involving metal exposure (odds ratio = 4.52, CI: 2.35–8.70) and forestry (odds ratio = 6.00, CI: 0.96–37.5) were among the most important determinants of the development of asthma. For women, the risk of developing asthma was higher among waitress activities (odds ratio = 3.03, CI: 1.10–8.31) than among work with cleaners (odds ratio = 1.42, CI: 0.81–2.48) and dental work (odds ratio = 4.74, CI: 0.48–46.5).
The performance of cleaning services as a risk factor for developing asthma was described in a study by Karjalainen et al.  that followed up with cleaning and office professionals for 12 years, noting that the odds ratio for asthma among cleaners was 1.5-fold (CI of 1.43–1.57) higher than that among professionals working in offices.
The number of women in our research was higher than the number of men in all groups of workers studied. Maçãira et al.  showed the importance of studying this population, given that the respiratory morbidity in internal cleaning workers in the metropolitan region of São Paulo reflected twice the length of exposure to risk factors for respiratory diseases, and the prevalence of inhaled accidents in women was three times higher than that in men.
Exposure to cleaning products is another known risk factor, and several studies show that an individual's susceptibility should also be taken into account, since although the work environment is the same for different individuals, some develop respiratory and other diseases do not .
Atopy and smoking are some of the characteristics described in the literature as factors that contribute to this scenario . It should be emphasized that in this protocol, all subjects were excluded from active tobacco use, with only a few former smokers, representing less than 2.5% of the population studied in our study (four individuals).
It is known that nasal and ocular symptoms are more important in the presence of high-molecular-weight agents than in the presence of lower-molecular-weight agents. Among cleaning workers, the use of low-molecular-weight products is more common, and many of these products are irritant .
Rhinitis of allergic origin may or may not induce the onset of asthma in people who have never had pulmonary diseases , such as in the study by Bauchau and Durham , who demonstrated that allergic rhinitis was more prevalent among cleaning professionals than in the general population. These data corroborate our findings, which demonstrated that individuals from the three groups of cleaning workers have more respiratory symptoms than office workers do.
The data found in our study on rhinitis demonstrated that both the presence of rhinitis-defining symptoms and self-reported rhinitis were greater among cleaners than among office workers. However, there was no relationship between these variables and the percentage of eosinophils or neutrophils. The absence of this relationship can be justified by the lack of specificity of the symptom questionnaires for the diagnosis of work-related rhinitis, since these are subjective and since we observed that there was an increase in the percentages of these cells.
The use of a score to assess the prevalence of asthma was validated by de Fátima Maçãira and co-workers , who used the ISAAC asthma module, which was composed of eight dichotomous aspects of asthma. The authors compared the responses between asthmatics with clinical diagnosis and healthy individuals (controls), with a sensitivity of 93% and specificity of 100% when using the cut-off score in the information set. Thus, despite the absence of clinical tests to prove the existence of asthma and rhinitis in our population, the high specificity and sensitivity of the scores justify the use of this instrument.
Folletti et al.  systematically reviewed 24 studies addressing the relationship between clean-up work and the risk of asthma and rhinitis and rephrased that an increased risk of asthma or rhinitis was demonstrated in 79% of the included epidemiological studies. Confirmation of this information was made mainly by objective tests, such as bronchial hyperreactivity or airflow obstruction. The specific causes associated with the onset of asthma and rhinitis were the level of exposure to cleaning products, sprays, bleach, ammonia, product mix and specific work tasks.
In our study the time of service as well as the hours worked were crossed with the information of respiratory symptoms. We identified that the service time between the groups studied was the same. After this, we evaluated the differences among 3 service time ranges (up to 1 year, 2 to 5 years and over 5 years) and asthma and rhinitis symptoms.
In the first evaluation, there was no difference in asthma symptoms among workers according to the length of service intervals. However, for rhinitis symptoms, university workers with less than 1 year of functioning had fewer symptoms than the others did. These results differ from those found by Slavin  that report that the incidence of rhino conjunctival symptoms with occupational aetiology is higher in the first 12 to 20 months of professional activity, with a progressive increase when the exposure is continuous for 24 months.
Having to work over 20 hours weekly was more common among hospital workers with asthma symptoms. We believe that a longer work time is directly linked to the occurrence of more symptoms; the same result was found when symptoms of rhinitis were evaluated and rhinitis was confirmed, with a higher number of working hours evidenced in hospital workers. However, the alterations found in our population did not express nasal cellularity. In the analysis of the correlation between the time of service and the percentage of eosinophils and neutrophils, no significant difference was found.
When the type of analysis was adjusted for comparison rather than correlation, we identified that hospital employees and day labourers with less than 1 year of professional performance differed from each other with respect to the percentage of eosinophils but not neutrophils. Hospital workers have lower percentages of eosinophils, followed by housekeepers, and finally, university workers have higher percentages of eosinophils. These results, together with the significant values found for the duration of symptoms in professionals working in hospitals, convey that this professional category is more affected in both symptomatology and cellularity.
Considering the eosinophil count results in subjects with rhinitis from previous studies [ and comparing these values to those found in our study, it can be verified that the rate of eosinophils does not correspond to that expected for individuals with rhinitis in all groups studied, i.e., greater than 5%. However, the percentages of the three groups of cleaning workers were higher than those found in the control group (hospital: 0.7 ± 2.4; university: 1.2 ± 3.4; housekeeper: 0.7 ± 1.7 control: 0.05 ± 0.1; percentages of eosinophils).
This same justification is exemplified in the study by Pal et al. , that showed that the difference in the mean eosinophil counts of patients with allergic rhinitis and controls was statistically significant, and a nasal smear eosinophil count of > 0.3 per high-power field (HPF) had 100% specificity and 100% positive predictive value for allergic rhinitis. Asthma was associated with allergic rhinitis in 40% of patients; an association was not found between nasal smear eosinophil count and the symptoms, duration, type, and severity of allergic rhinitis or coexistent asthma. These authors conclude that an eosinophil count of > 0.3 per HPF in nasal smears is a highly specific criterion for the diagnosis of allergic rhinitis. When grouping and comparing all cleaners who answered "yes" to the question of the presence of rhinitis and asthma regardless of length of service, these responses differed significantly for those who answered negatively to the same questions. As found in this study, evidence of changes in cell rates related to work-related rhinitis is described in several other studies .
Lovato et al.  compared a group of carpenters with non-exposed individuals to determine whether exposure to wood dust was correlated with specific patterns of inflammatory or infectious rhinitis. The authors identified that carpenters reported significantly more nasal symptoms than the control group (p = 0.0007). The nasal smears of the carpenter group contained significantly more neutrophils (p < 0.00001) and lymphocytes (p = 0.02) than did those of the control, indicating that nasal cytology was able to reveal chronic inflammatory rhinitis in a significant proportion of carpenters, highlighting the potential of the technique in the screening of this pathology.
Gelardi et al.  also agree with the potential of the nasal cytology technique and emphasize that it deserves it place in the arsenal of diagnostic techniques for chronic rhinitis because it is an easy, reliable and inexpensive method and in the absence of other diagnostic tools, it can be used to provide adequate treatment to patients.
When investigating inflammatory factors in children with rhinitis and asthma, Marcucci and co-workers  found significantly higher IgE levels in the nasal mucosa during the summer, although the allergen in question (mites) was more prevalent in the winter, as the authors state. In this way, the temperature itself of the environment in which the individual resides can be an important factor to consider.
A limitation in relation that no specific equipment was used to determine the levels of chlorine or other air components in the exposure atmosphere. The patients also did not undergo a clinical evaluation and classification in relation to symptoms was made according to the answers to the questionnaires.
As strengths of this study, we investigated associations between asthma and occupational exposure and several cleaning agents. We believe that further studies revealing the implicit risks of using cleaning products are of great value for this profession, which has been growing in recent years in large cities. We emphasize the importance of the continued investigation. In addition, future studies are necessary can clarify the risk of the use of these chemical agents, with the goal of greater adherence to the use of personal protective equipment, as well as preventive measures to minimize the risks to cleaning employees regardless of where they work.