Translation:About Efficiency of Individual Protection Equipment of Respiratory Organs as Prophylactics of Diseases (review)

Abstract: The review of publications evaluating the effectiveness of personal respiratory protection (RPE) as means of reducing morbidity (occupational and morbidity with temporary loss of ability to work) and indicators of degree of purification of the inhaled air is presented. It is revealed that with a high degree of probability, systematic studies in this field were not carried out and that in some cases the effectiveness was overestimated by incorrect justification.

Key words: RPE, efficiency, protection factor, occupational diseases

Introduction. The share of workplaces where workers are exposed to excessive exposure to harmful and / or dangerous production factors has increased significantly in the Russian Federation. This growth has made the use of personal protective equipment (PPE) an important way to protect the health of workers. However, there are few publications about how the usage of the respiratory protective devices (RPD) helps prevent the development of occupational diseases. Due to significant differences in the approaches to the choice of the respirators in RF and Western countries, the use of Western data for conditions in the RF will be incorrect. According to the instructions of professor V.F. Kirillov, a search was made for information on the effects of respirators on occupational morbidity (during the preparation of the survey [1]), but it ended in failure. This search was continued, and we dedicate this work to the blessed memory of professor Kirillov.

In order for the respirator to be able to effectively protect the worker, the following conditions must be met:

(1) An employee must use his/her RPE in a timely manner.

(2) The respirator must provide the worker with a breathable air, and

(3) The respirator should separate the respiratory organs from the surrounding polluted atmosphere.

Compliance with requirement No. 1 is hampered by the negative impact of PPE on the employee (deterioration of the field of vision, increased resistance to breathing, discomfort, etc.). Compliance with requirement No. 2 is hampered by the unreliability of the olfactory organ's reaction to the smell of a toxic substance (the appearance of odor is widely used in the RF as a sign of the need to replace gas filters). Compliance with requirement No. 3 is hampered by the formation of gaps between the mask and the face through which unfiltered air enters the mask and the respiratory system of the employee. These gaps appear more frequently in the workplace (and they are larger), but rarely in laboratory conditions. Therefore, employers (in Western countries) are obliged to use respirators only when other methods of protection are not sufficiently effective. Employers should choose respirators, given the fact that the air supply to the mask significantly improves the protective properties of respirators (this reduces or eliminates the reduced pressure in the mask during inhalation); significant difference between workplace and laboratory performance. Also, the employers is obliged to ensure the timely replacement of gas filters, and fit testing of masks.

Materials and research methods. We looked for such articles in which there was information about: (1) about occupational morbidity of workers before and after starting to usage of the RPE; (2) type / model of RPE; (3) air pollution (chemical composition and concentration; or the degree of excess of the maximum permessible concentration MPC); and (4) the degree of the air pollution was similar before and after starting to use the RPE.

At the first stage of the research, we studied the publications of the specialists of the occupational diseases and occupational safety and health. At stage 2, we studied the books of leading specialists of the RPD. This reduced the risk of missing important articles and the potential impact of a conflict of interest, as the RPD developers often tend to overestimate the consequences of the usage of their production.

Results and discussion. At the first stage, we checked ~ 28 journals and periodicals: (Table 1), including journals: Almanac of Clinical Medicine (publications for the period 1998-2016); Health risk analysis, (publications for the period 2013-2016); Safety in technosphere (2006-2016); Life Safety (2002-2016); Occupational health and safety (2006-2016); Worker protection from silicosis (1953-1986); Vektor Nauki of Togliatti State University (2009-2015); Siberian Journal of Science (2011-2016); Health Care of the Russian Federation (1957-2016); Health Care of Kazakhstan (1945-95; new name: Medicine; 2012-2016); Mining information and analytical bulletin (1992-2016); Medical and technical problems of personal protection of workers, 9 issues (1969-1982); Scientific work of the institutes of labor protection of the All-Union Central Council of Trade Unions (1960–1975); Occupational diseases of dust etiology (1967-1991); Radiation hygiene (2008-2016); Modern problems of science and education (2005-2016); Civil Protection Strategy: Problems and Studies (2011-2015); Civil Security Technology (2003-2016); Fundamental research (2004-2016); Chemical Industry Today (2000-2016); Human Ecology (1994–2016); and 362 collections of scientific articles. We did not find any suitable articles in 6 journals (2001-2016).

This search revealed 842 articles in which the authors at least mentioned the use of respirators. But the cases of reduced occupational morbidity, which were described in part of these articles, usually occurred due to the improving of working conditions, and the use of the respirators - at the same time. Therefore, it was impossible to highlight the contribution of respirators in reducing the occupational morbidity of workers. The authors ([2] p. 13) noted that occupational disease specialists rarely study personal protective equipment, and that there are very few publications on the impact of respirators on the occupational morbidity of workers ([3] p. 26).

Table
 * 1) If the article described the usage of 2 or more types of the respirators, then this article was converted: 1 article was divided into 2 or more separate articles with information about respirators of the 1 type.
 * 2) The number of articles before their conversion (described in paragraph 1 above) is shown at the top, and the number of articles after their conversion is shown below.
 * 3) The number of articles in which there were numerical indicators of the workers' health. The number of articles with more detailed information is shown at the top; the number of articles with less complete information is shown in brackets below (italics).
 * 4) The number of articles in which respirators showed low efficiency (opinion of the authors of the article; registration of high contamination of inhaled air inside the mask, exceeding the maximum permissible concentration; detection of inhalation intake of toxic substances, etc.). The number of such articles, from among the articles with more detailed information on the workers' health, is shown at the top (see paragraph 3 above). And below shows the number of such articles, among those with less complete information about the workers' health. The number of articles containing at least some information about the health of workers and the effectiveness of respirators at the same time is shown in brackets.

1. Evaluation of respirator effectiveness (stage 1) 

Articles were transformed: if there were estimates of different types of respirators in 1 article, then it was divided into 2 or three articles with information about respirators of the same type. So we got 965 articles. Information on the effectiveness of respirators and on the health of workers (simultaneously) was in 47 articles; and such information (but less complete on the health of workers) was in 48 articles.

The case of complete and sustainable (for 6 years) elimination of occupational diseases of workers is described in one article. It happened when applying the supplied-air respirator. These SAR supplied conditioned air to the facepiece (if the air in the workplace was heavily polluted); and if the air was slightly polluted, half-masks were used [4]. In addition to this article, 8 publications declared the high efficiency of respirators. Such declarations were made on the basis of: elimination of cases of acute poisoning; on the basis of some reduction of morbidity of workers; or it was the opinion of the authors (without information about the morbidity of workers; and / or if there is information showing the preservation of occupational morbidity of workers). In 86 other articles, the effectiveness of respirators was assessed as low. We compared the articles about respirators with the forsed air supply into the facepiece (pressure-demand air supply mode, continious flow air supply mode, or Powered Air Purifying Respirators PAPR), and without such supply (negative pressure). The share of publications, where the effectiveness was rated as high, was higher among articles on respirators of the first type than among articles on respirators of the second type (5.6 times: 50% and 8.9%).

The tendency was found: in those articles where there was no information on the workers' morbidity, the share of articles with (declared) high efficiency was significantly higher than in those where there was information on the workers' morbidity (4.9 times, 46.5% and 9.5%). This trend shows why many articles declare the high efficiency of respirators (since such articles very rarely contain information about the health status of workers).

If the authors did not use information on the workers' health, their declarations on the high efficiency of respirators can be caused by the previously published materials (in Russian), which declared high efficiency or respirators for decades (they are discussed below). A similar trend exists in the West. In developed countries, the use of respirators is limited by the Assigned Protection Factors (APF), developed for all types of respirator. If the concentration of harmful substances is higher than the product of the APF on the maximum permissible concentration (MPC), the respirator of this type is prohibited to use in such conditions. The values of APFs were developed on the basis of measurements of protection factors at the workplace (in the USA). In other countries, measurements of the PF in the workplace were conducted rarely, or not at all. The APFs values in the United States are lower than in other countries. For example, for negative pressure full face masks, APF in the US = 50, and in Germany 400; for negative pressure half-masks 10 and 30 [5,6]..

Measurements of the workplace protection factors of respirators (or measurements of degree of the ingaled air pollution, in mask) has been described in approximately 40 articles. Ten articles were published before 1961, and those respirator models were no longer used. Measurements of respirator's workplace protection factors help to determine the technical perfection of these device, but do not provide information about the health of workers. The results of measurements at workplaces were used in the West to prevent the issue of inefficient respirators to workers (due to the development and application of the APFs) [1,7]. Measurements of the workplace protection factors in the USSR and in the RF were carried out rarely and haphazardly (unsystematic). For comparison, about 70 studies were conducted in the West in 1972-2015. There are no information to determine the quality of measurements, described in those articles; significant systematic errors are possible [8]. The effectiveness of respirators was declared as high in 18 articles, but none of them contained any information about the occupational morbidity of workers.

In general, the low efficiency of respirators (as the means of preventing occupational diseases) can be explained by: the choice of respirators' type, that did not meet the working conditions in their protective characteristics; the mask did not match the shape and / or size of the face (no fit test); the late replacement of gas filters; and the fact that the workers did not always use their respirators in a polluted atmosphere. The conditions for the selection and use of respirators in the USSR and in the USA are different; but specialists in occupational morbidity of workers made similar conclusions:

(Academician A.Letavet [9] p. 5) “It is well known how ineffective ... trying to compensate the harmful workplace conditions with ... the use of respirators by employees”.

(Mark Nikas, p. 426 section "Conclusions" [10]) - about those workers who do not receive the required protection due to the instability of the protection factors of respirators: "Unfortunately, the only certain way of reducing the exceedance fraction to zero is to ensure that Co (note: Co - concentration of pollutants in the breathing zone) never exceeds the PEL value.”.

Evaluation of the effectiveness of respirators (stage 2) 

At stage 2, we studied 10 books of leading Soviet and Russian specialists on respiratory protection. In two books, occupational morbidity of workers was mentioned. In the book [3] references were made to articles published in Western journals. Since the conditions for the selection and use of respirators in the West are noticeably different, such links are incorrect. The authors of the books [3,11 ] also referred to the articles that we found at stage 1.

2.1 Matching sources: pneumoconiosis (in: [3] p. 28, source No. 1.1) 

Quote from the original source ([12] p. 90): “The incidence of cases of the pneumoconiosis decreased by 2.5, 2.7 and 7 times. ... This decline was due to the development and implementation of a large number of measures to improve working conditions, improve the health of workers, and improve their health care. The usage of dust respirators gives some effect. ”

For reference: according to the source ([13], p. 221) dust concentration in the coal mines (in the same region) decreased 3.4 times for the period 1963-1974.

How respiratory specialists cited this text in their book ([3], p. 28, reference No. 1.1): “... the incidence of cases of pneumoconiosis decreased 2.5–7 times in 20 years. According to the authors [12], the use of soviet filtering negative pressure half-mask respirators (that providing a protection factor of 100) reduced the coal dust inhalation ...”. Actually, there is no information about the contribution of respirators to reducing the incidence of cases of the pneumoconiosis (as the miners used respirators before) in [12]; there is no any information on workplace protection factors of miners’ half mask respirators; and authors of [12] unambiguously indicated that it was not possible to eliminate the incidence of cases of the pneumoconiosis among coal miners after continued use of the respirators by them.

2.2 The coincidence of sources: Ust-Kamenogorsk plant (Kazakhstan) 

Working conditions at the lead-producing plant worsened. This prompted to work on improving workplace conditions, and workers began to use respirators to protect against lead dust (negative pressure filtering half-mask “Lepestok”). As a result of improved workplace conditions, the number of cases of lead intoxication in one workshop decreased 5 times. As a result of the simultaneous improvement of working conditions and the use of a respirator, the frequency of lead intoxication in another workshop decreased 20 times [14]: «The filter media in the respirator «Lepestok» collect fine lead dust very effectively. For this reason, as well as due to the improvement of working conditions, the occupational morbidity of workers when exposed to lead was completely eliminated in the smelting shop; it was decreased in the sinter shop by 20 times compared with 1958. The decrease in occupational morbidity in the smelting shop in comparison with 1958 was small, 5 times, until a respirator was used at the beginning of 1958 year ... ».

After the publication of the article [14] describing occupational morbidity at this plant, another 12 articles were published on this problem at the same enterprise (for the period from 1964 to 1990). The authors of subsequent publications noted that the concentration of lead dust in the air continues to exceed the safe value. Also, these articles describe the reduction in the number and severity of occupational lead intoxications and reduction in overall morbidity, caused by improved workplace conditions. But cases of lead poisoning continued to occur, sometimes after a short period of work (2-3 years). With high probability we can say that it was not possible to achieve the timely use of a respirator «Lepestok» for 28 years.

How respirator specialists cited this text in [11] (p. 239): “The respirator «Lepestok» began to be used by workers everywhere. After that, the occupational lead intoxications decreased to zero in the smelting shop, and it decreased 20 times in the sintering shop. There is no doubt that the main reason for this decrease in incidence is the use of a respirator ... ”. This quotation distorted the meaning of the article [14]; and the respirator specialists did not quote no one of all other articles (on the occupational morbidity at this plant), publised before the their book [11].

2.3 Biological monitoring of exposure to the radioactive dust

The respirator specialists described a decrease in the inhalation intake of the plutonium dust for the employees in the nuclear industry plant, who began to use the «Lepestok» in the late 1950s - early 1960s ([11] pp. 246-249). In the two editions of this book, (published in 1984 and in 2015) they did not indicate: in which plant this study was conducted; if where was the replacement of workers with great work experience by new ones; and them did not indicate the concentration of the plutonium dust in the workplace air even once. The authors calculated (PF) under their assumption that the concentration of the plutonium dust in the air did not change for more than 5 years. The authors carried out calculations of the degree of purification of inhaled air when workers applied a respirator (table 8.1, for the each year over a period of 6 years). If one use the data from this table, and if he or she calculate the PFs for each year (not only mean value), one can get that PFs were below zero in 1957 and 1959. If one used the average value for 6 years, then PF = 33. The authors found it appropriate to use the average value, but only after its correction for the oral intake of plutonium in the body. In their opinion, oral intake was 2% of the potential inhalation intake (if respirators were not used). As a result of their correction, the mean PF = 100. If one apply this correction for the each of 6 years (not just to the average value) the PFs were below zero for 3 years out of 6.

The degree of air pollution by radioactive substances was very high in the initial stage of development of the atomic industry of the USSR. According to ([15] p. 235) there have been cases of exceeding the MPC up to 225 thousand times. A significant improvement in working conditions ([16] p. 36) led to a sharp decrease in occupational morbidity, and this decline began from 1955-1958. These facts do not agree with: the suggestion made by specialists in respirators that the concentration of the plutonium dust did not change in 1955-1961; not consistent with the lack of information on the concentration of the plutonium dust; and the lack of data on the location of the workplaces. For example, according to [17], there were cases of excessive exposure of radioactive substances to a part of workers during usage the «Lepestok» in the nuclear industry in the 1970s and later,. The authors [17] suggested that the reason is not using respirators by employees while working in a polluted atmosphere. According to ([15] p. 266), the contamination of the outer and inner sides of the respirator «Lepestok» differed 10-42 times. The degree of decrease in the concentration of the plutonium in the urine (measured using biological monitoring in the period 1958-1964) is 9 times [11]. This value is similar to the Assigned PF for negative pressure half mask respirators 10 (United States [5]) and is not similar to the PF = 100 ([11] calculated by the respirator specialists) and with the declared PF = 200 (the same model [18]).

2.4 Analysis of other results that were found in the second stage of work  The authors of the some of found articles justified the ability of respirators to prevent the appearance of occupational diseases, and them based this opinion on the PFs, measured on the workplaces. Some authors made such justification by taking measurements not in the workplaces, but in laboratory conditions (with the involvement of testers, with using dummies, as well as securing the respirator in a clip with a gasket that prevented penetration of the unfiltered air through the mask seal [18]. However, the respirators’ PFs are not the indicators of the health status of workers. Western researchers have conducted dozens of studies of PFs in the workplace. The results show that workplaces’ PFs can be ten times lower than in laboratories. For this reason, laboratory results cannot be used to estimate workplace PFs [11,19,20]. Measurements in laboratory conditions revealed cases of lowering the protection factors for the negative pressure half masks (for example, to 5.5-5.7 [21]); and it was recommended to limit their use to the low concentrations (≤ 10 MPC, [22] p. 80).

3. Other research results

The respirator «Lepestok» was widely used when working at the Chernobyl nuclear power plant after the disaster. The experts evaluated its effectiveness in these conditions (that was declared previously in the state standard [18]: PF = 200). The experts got different results. For example, according to the estimates of the All-Union Civil Defense Research Institute, the PFs were from 2 to 8 ([23] p. 11-12 ); the Institute of Biophysics estimate PFs from 5 to 10 [24]; and according to estimates of the Integrated Expedition at the Institute of Atomic Energy named after I.V. Kurchatov, PFs were from 3.3 to 10 ([25] p. 22). The laboratory of Lovelace Respiratory Research Institute (US Department of Energy) conducted independent tests on the «Lepestok». When the respirator was used by testers under laboratory conditions, the PFs exceeded the declared value (200) only in 20% of cases. For the 4 testers (total number = 25), the PFs exceeded 5; and the minimum value was 1.5. The representatives of the organization that developed this half mask respirator, commented these results as follows: “The fact that the PFs were above 200 in 20% of cases means that the total inward leakage did not exceed 0.5%. Therefore, the respirator «Lepestok-200» is fully consistent with the declared values of its effectiveness in [18].”

(Note: for this half mask negative pressure air purifying respirator, the expected (declared) protection factor is always indicated = 200, for example, standard [18]). The representatives of the organization that developed this respirator model, ignored all the results that were obtained not in the laboratory of the US Department of Energy.

The document ([27], p. 45) describes the conducting of the biological monitoring. The workers used negative pressure filtering respirators (with half mask facepieces). As a result, the concentration of metabolite of the toluylene diisocyanate in the urine decreased 10 times. This degree of reduction corresponds to the Assigned PFs (APF) of half mask respirators in the USA [5]. The result of this biological monitoring is also consistent with the results described in 8 articles (found at stage 1, published in the period from 1963 to 2012). These articles describe the histological analysis of the lungs tissues of the miners (which suddenly deceased due to accidents etc., but not due to occupational diseases). In general, there are data on more than 110 miners who regularly underwent medical examinations, and all were considered healthy. The lungs tissues analysis showed that all these miners had at least the initial signs of the pneumoconiosis. An assessment of the PFs of the respirators used in the uranium mine, yielded a result 1.2–2 [29]. Author used data from measurements of dust concentration in the mine, and measurements of the radiation from the samples of the lungs tissues of the 326 dead miners to calculate this result.

The overwhelming majority of the articles found (published in Russian) show that the effectiveness of respirators is low or insufficient. This corresponds to the point of view of Western experts (that the use of respirators is the least reliable way to protect workers), but does not agree with the opinion of some specialists on respirators (in the USSR and in the RF). We believe that the point of view of this part of respirator specialists is incorrectly justified.

The fact that workers do not use their respirators in a polluted atmosphere in all cases, partly explains their low reliability as a means of preventing occupational diseases. This problem exists in Western countries, and it is not fully resolved. There are a number of reasons in the RF that make this problem more frequent and stronger. The respirators, issued to workers, often do not meet the working conditions for their (assigned) protection factors; their half and full masks may not met to the shape and/or size of persons faces (fit test is not carried out); replacement of gas filters may be too late; all this has been going on for decades. For these reasons, a persistent conviction arose among (part of) workers in the RF that they were given respirators not for their health preservation but for the formal fulfillment of legal requirements (to report on compliance with the laws), «for show» only. This opinion of ordinary workers is also shared by a number of managers who are faced with the consequences of using «very reliable» respirators. We believe that if respirators are obviously insufficiently effective, do not correspond to the working conditions in their assigned PFs, then it is unrealistic to require workers to continuously use such respirators; and it is senseless and unethical.

Conclusions
 * 1) Probably, the systematic study of the impact of respirators on the occupational morbidity of workers was not a priority.
 * 2) In most cases, the use of respirators by workers does not eliminate the causes of chronic occupational diseases.
 * 3) The declared high efficiency of respirators often does not correlate with data on occupational morbidity; does not correspond to the modern level of world science; and is proved incorrectly.
 * 4) The current requirements for the certification of respirators, the requirements for their selection and use - do not exclude the choice and use of obviously insufficiently effective types of respirators in the Russian Federation, and de-motivate workers to use respirators in a timely manner.
 * 5) The development of requirements for the respirators and for their selection and use should be carried out with the active participation of occupational and safety spesialists, and trade unions to prevent conflicts of interest.

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