Microbiological Quality of Indoor Air in University Rooms

Original Research

Polish J. of Environ. Stud. Vol. 16, No. 4 (2007),

Introduction

Most people spend over 90% of their lives indoors:

in houses, offices, and schools [1], where they are exposed

to some indoor environmental factors (bioaerosol)

that influence their health and physical condition.

Therefore there has been a growing interest in indoor

microbe studies in recent years [1-14]. The aim of those

studies is not only estimation of the airborne microorganisms

but also their identification and the determination

of factors influencing bioaerosol composition inside

the rooms.

Biological contamination of indoor

air is mostly

caused by bacteria, moulds and yeast. They can be dangerous

as pathogenic living cells but they can also secrete

some substances harmful for health. These are different

kinds of toxic metabolism products, for example mycotoxins

[4, 11, 15,]. Epidemiological studies show that too

high concentration of microorganisms in the air can be

allergenic; however, sometimes even very low concentrations

of some particular microorganisms can cause

serious diseases. It is supposed that about 30% of health

problems relevant to the indoor air quality is the result of

a human organisms reaction to moulds [10]. Fungal flora

can be hazardous for health, particularly in rooms with

heating, ventilation and air-conditioning (HVAC) systems

[10, 11, 16-18] and can breed allergies [4, 5, 16-19], SBS

symptoms (“sick building syndrome”) causing irritation

of mucous membranes, bad physical condition, tiredness,

headaches, vertigo, decrease of concentration, memory

and intellectual work ability [10, 19, 20], dermatosis, respiratory

diseases (including asthma) [4, 8, 10, 12, 16, 17]

and cancers [4, 5, 9, 10, 12-14, 21]. The amount of pathogenic

microorganisms is higher in indoor than outdoor air

[1, 11, 22, 23].

Microbiological Quality of Indoor Air

in University Rooms

M. Stryjakowska-Sekulska, A. Piotraszewska-Pająk*, A. Szyszka, M. Nowicki,

M. Filipiak

Chair of Biochemistry and Microbiology, Poznań University of Economics,

al. Niepodległości 10, 60-967 Poznań, Poland

Received: September 27, 2006

Accepted: March 11, 2007

Abstract

A study on indoor air microbiological contamination in various rooms of university buildings in Poznań,

Poland, is presented. Investigations were conducted in the period September-October 2002 and the same

period in 2003. Air samples were taken twice a day: in the morning and in the afternoon. In all of the tested

places a multiple growth of bacteria and significant increase of mould spores was observed in afternoons.

The predominant bacteria and moulds isolated from investigated air samples were: Staphylococcus spp.,

Micrococcus spp., Serratia spp., Aspergillus spp., Penicillium spp., Rhizopus spp., Cladosporium spp. and

Alternaria spp. Among these microbes the presence of pathogenic and strongly allergenic microorganisms

was detected.

Keywords: indoor air, microbiological quality, airborne bacteria, airborne fungi, biomass

*Corresponding author; e-mail: a.pajak@ae.poznan.pl

623-632

624 Stryjakowska-Sekulska A. et al.

So far there have been no Polish standards or guidelines

for microbiological quality of indoor air. Furthermore,

there isn’t any European Union directive addressing this;

therefore, it is assumed to be based on particular European

countries’ requirements and scientific propositions [24].

According to current Swedish requirements the number of

500 colony-forming units (cfu) of bacteria and 300 cfu of

fungal spores in 1 m3 can be accepted in an indoor environment

[25]. Especially air contamination caused by fungi is

taken into consideration because of their extremely dangerous

influence on human health. However, it can be noticed

that during the last 20 years opinions concerning innocuous

fungal spore amounts in the indoor air of various kinds of

rooms have varied [26]. According to Berk et al., in 1979

exposure of 20 cfu/m3 to over 700 cfu/m3 has no harmful effect

[27]. Conclusions shown in The Netherlands Research

Methods in Biological Indoor Air Pollution (1989) describe

the amount of fungi over 104 cfu/m3 or the amount of particular

species of mould over 500 cfu/m3 as dangerous for

health. In 2001 the American Industrial Hygiene Association

(AIHA) published a proposition of guidelines for the

amount of fungal spores in different indoor environments,

for example residential and commercial buildings. Guideline

for residential buildings are less than 500 cfu/m3 and for

commercial buildings are less than 250 cfu/m3 [26]. Other

countries’ requirements are similar. In Brazil total amount

of airborne microorganisms (especially fungi) in enclosed

space shouldn’t exceed 750 cfu/m3 [28]. In Hong Kong

good microbiological class air should include less than 1000

cfu/m3 of bacteria. If it includes less than 500 cfu/m3 – air

is classified as excellent [29]. In Singapore requirements for

indoor air quality strictly describe concentration of bacteria

on the maximum level of 500 cfu/m3 [23].

The aim of this work is long-term observation of

microbiological quality of indoor air in selected rooms

of university buildings located in the centre of Poznań,

where thousands of people spend several hours studying

and working in enclosed spaces every day and

where microbiological quality of indoor air can influence

their health and physical condition. This publication

presents preliminary results of an indoor air study

conducted in 2002 and in 2003. The study embraced a

measurement of the concentration of bacteria and fungi

in the air of selected rooms and microbial composition

of the air.

Materials and Methods

Microbiological quality of indoor air was investigated

in select university rooms specified in Table 1.

Total number of mesophilic aerobic bacteria, yeast and

moulds in the air of selected rooms was determined using

Koch sedimentation method according to Polish Standard

PN 89/Z-04008/08 [30]. Air microorganisms were settled

gravitationally directly on the Petri plates filled with nutrient

media and exposed in sampling points for a period of

time. The number of microorganisms expressed as CFU/

m3 was estimated according to the equation [30]:

CFU/m3 = a · 10000/p · t · 0.2

where:

a – the number of colonies on the Petri plate

p – the surface of the Petri plate

t – the time of Petri plate exposure

Table 1. Characteristic of sampling rooms.

Investigated rooms Mark *

Characteristic of rooms Number of

Petri dishes

from one

point

Number of

Petri dishes in

one sampling

Number of

total Petri

dishes

Area

[m2] Cubature [m3] Number of

persons

Lecture room1 A 253 1391.5 230 24 (x 2) 10 480

Lecture room2 B 104.7 418.8 120 24 (x 2) 6 288

Chemical laboratory C 68.6 184.5 18 24 (x 2) 3 144

Library D 362.8 870.7 24 (x 2) 5 240

Reading room E 2064 9690 24 (x 2) 10 480

Dean’s office F 32.1 94.4 4 24 (x 2) 3 144

Canteen G 229.1 673.6 300 24 (x 2) 15 720

Toilets H 11 39.6 24 (x 2) 3 144

Corridor I 115.5 339.6 24 (x 2) 4 192

Total 48 59 2832

* Symbol used in figures 1 and 2

1 Lecture room with ventilation system

2 Lecture room without ventilation system

Microbiological Quality... 625

Results obtained by Koch sedimentation method are less

accurate then those from impaction methods with the use of

an air sampler. However, the sedimentation method is still

quite popular in Poland and some other countries [6, 12,

14, 31-33]. The method does not require expensive instrumentation,

it is cheap and simple and it is recommended by

Polish Standards. Sedimentation method does not permit

exact quantitative determination, some earlier observations

reported that results of sedimentation method are usually

higher than numbers obtained with the use of air samplers

[14, 31]. However, data collected by sedimentation method

allow the drawing of correct conclusions on types of microorganisms

present in the air and can give a rough approximation

of bacterial and fungal concentration.

For the determination of microorganisms in the air

of investigated rooms Petri dishes were exposed for 15

minutes. There were 12 series examinations made. All

samples were taken in September (before the beginning

of the academic year) and October (during academic year)

in two running years – 2002 and 2003. There were two

periods in a day of taking samples. The first one in the

morning from 730 a.m. to 8 a.m. (before the beginning of

lectures) and the second one in the afternoon from 230 p.m.

to 3 p.m. (before the end of lectures). The total number of

samples was 2,832.

The following microbiological media were used:

– Y east Extract Agar (Merck) to determine the total

number of bacteria;

– Sabouraud Agar medium with 2% of glucose (Merck)

for quantification of fungi;

– Czapek-Doxa Agar (BTL) for filamentous fungi identification.

Petri dishes were incubated for 24–48 hours at 37oC

(to determine the total number of bacteria) and for 10

days at 25oC (to enumerate fungi). Results were shown by

colony forming units in 1 m3 of air (cfu/m3).

Bacteria were identified by three arrays. The first one

– macroscopic estimation (description of colony). The

second one – microscopic estimation (dyeing by Gram

and Schaeffer-Fulton method). The third one – biochemical

tests according to bacteria classification according to

Bergey [34].

Diagnosis of filamentous fungi was based on estimation

of morphological features of growth on Czapek me-

Table 2. Microbiological air contamination inside university rooms.

Investigated rooms Time of taking

samples

Total number

of bacteria

[cfu/m3]

Number of

filamentous fungi

[cfu/m3]

2002 2003 2002 2003

Lecture room1

morning 3.9 x 102 6.3 x 102 5.2 x 102 3.3 x 102

afternoon 5.2 x 102 8.8 x 102 2.6 x 102 2.6 x 102

Lecture room2

morning 1.3 x 102 3.6 x 102 2.6 x 102 2.3 x 102

afternoon 3.2 x 102 8.8 x 102 5.2 x 102 2.6 x 102

Chemical laboratory

morning 1.2 x 102 1.1 x 102 1.6 x 102 0.9 x 102

afternoon 6.5 x 102 3.8 x 102 3.9 x 102 5.2 x 102

Library

morning 1.3 x 102 3.6 x 102 2.6 x 102 1.3 x 102

afternoon 2.6 x 102 2.6 x 103 2.6 x 102 3.0 x 102

Reading room

morning 1.3 x 102 8.7 x 102 1.3 x 102 1.1 x 102

afternoon 1.3 x 102 1.7 x 103 1.1 x 103 8.0 x 102

Dean’s office

morning 1.3 x 102 7.8 x 102 2.6 x 102 2.0 x 102

afternoon 1.3 x 102 9.1 x 102 3.9 x 102 4.0 x 102

Canteen

morning 2.6 x 102 6.6 x 102 1.3 x 102 1.3 x 102

afternoon 1.0 x 103 1.5 x 103 2.6 x 102 2.3 x 102

Toilets

morning 1.4 x 103 1.4 x 103 2.6 x 102 2.6 x 102

afternoon 2.3 x 103 3.3 x 103 7.8 x 102 5.6 x 102

Corridor

morning 2.6 x 102 1.1 x 103 1.0 x 103 2.0 x 102

afternoon 1.3 x 103 1.7 x 103 1.0 x 103 2.0 x 102

1 Lecture room with ventilation system

2 Lecture room without ventilation system

626 Stryjakowska-Sekulska A. et al.

dium as well as on microscopic observation according to

filamentous fungi estimation guide [35].

Results

Variation of Microorganism Concentrations in the

Air of University Rooms

The average level of microbiological air contamination

inside investigated university rooms is shown in Table

2. The number of microorganisms (bacteria and fungi)

in indoor air varied widely in the whole research period.

The total number of mesophilic aerobic bacteria in 2002

ranged from 120 to 2300 cfu/m3, while the total number of

fungi ranged from 130 to 1100 cfu/m3 and in 2003 it varied

from 110 to 3300 cfu/m3 and from 90 to 800 cfu/m3,

respectively.

Microorganism concentrations in the air varies not only

in the course of a season but also throughout the day.

Average number of bacteria and fungi present in indoor

air of different rooms in mornings and afternoons

during both years of studies were compared in Figs. 1 and

2. In 2002 a concentration of bacteria in investigated lecture

rooms was higher than fungal concentration, whereas

in 2003 a fungal domination was observed. In mornings

bacterial and fungal air contamination was always lower

than in afternoons. There was one exception – a ventilated

lecture room. Results of studies in this room showed

lower amounts of moulds in 1 m3 of air in afternoons than

in mornings (about 50% less in 2002 and 22% less in

2003). Very intensive bacterial growth in afternoons was

observed in the corridor (in 2002 bacterial concentration

in afternoons was 5 times higher than in mornings), in the

canteen (in 2002 about 4 times higher in afternoons than

in mornings), in the library reading room (in 2003 about

7 times higher in afternoons than in mornings) and in

the chemical laboratory (in 2002 almost 5.5 and in 2003

– 3.5 times higher in afternoons). The rest of air samples

presented lower bacterial growth during the day, i.e. 1.3

to 2.5 times higher in afternoons than in mornings. The

highest growth of fungal contamination during afternoons

was observed in the chemical laboratory (in 2003 – 5.8

times higher in afternoons than in mornings) and in the library

reading room (in 2002 – 8.5 and in 2003 – 7.3 times

Fig. 1. Concentration of bacteria in air inside selected university

rooms in 2002 (A) and in 2003 (B): A – ventilated lecture

room, B – non-ventilated lecture room, C – chemical laboratory,

D – library, E – reading room, F – Dean’s office, G – canteen,

H – toilets, I – corridor

Fig. 2. Concentration of filamentous fungi in air inside selected

university rooms in 2002 (A) and in 2003 (B): A – ventilated

lecture room, B – non-ventilated lecture room, C – chemical

laboratory, D – library, E – reading room, F – Dean’s office,

G – canteen, H – toilets, I – corridor

Microbiological Quality... 627

higher in afternoons than in mornings). In the remaining

air samples the level of fungal growth was lower, i.e. up

to 3 times higher than in mornings.

Variations in concentration of bacteria and fungi in the

air of selected rooms in both years of studies were shown

in Figs. 3 and 4. In 2003 a distinct increase of both bacteria

and fungi concentration in the lecture room was observed

on the date of the opening academic year (Fig. 3). Right

after this time the microbial concentration was lowered.

One year earlier, variations were not so deep. Dramatic

but transient increase of bacteria at the beginning of the

academic year was observed in both investigated years

in toilets (Fig. 4), whereas the fungal concentration was

stable and kept at a much lower level.

Simultaneous outdoor air studies [36] in the vicinity of

university buildings made it possible to estimate the I/O

ratio (the indoor/outdoor concentration ratio) for investigated

university rooms. The I/O ratios for both bacteria

and fungi in most investigated rooms were in the range of

0.1–0.7 and they were always lower in the mornings than

in the afternoons. Though there was an exception – a ventilated

lecture hall where I/O ratios observed in the afternoons

(0.4 in 2002 and 0.3 in 2003) were lower than in the

mornings (0.8 in 2002 and 0.4 in 2003). Extremely high

values of I/O ratios in afternoons reaching 1.3–3.5 were

found in 2003 in the following rooms: librarian lending

room and reading room, canteen, corridor and toilets.

Qualitative Analysis of Air in University Rooms

Microbiological quality of indoor air is created not only

by a total concentration of bacteria and fungi but by the

presence of some particular microorganism species, which

is very important for the health of people occupying the

room. Analysis of bacterial flora composition in investigated

university rooms revealed dominating contributions

of bacteria from the following genera: Micrococcus spp.,

Bacillus spp., Staphylococcus spp. (e.g. Staphylococcus

aureus), Sarcina spp., and Serratia spp. Also some Gram

negative bacteria belonging to Escherichia genus were

isolated from indoor air of toilets. Quality characteristics

of fungal flora isolated from the air of educational rooms

showed dominating contributions of such species of fungi

like: Cladosporium spp. (e.g. Cladosporium herbarum),

Penicillium spp. (e.g. Penicillium chrysogenum, Penicillium

viridicatum and Penicilluim expansum), Aspergillus

spp. (e.g. Aspergillus niger and Aspergillus flavus). Genera

Cladosporium herbarum, Alternaria alternata, Mucor

spp., Rhizopus nigricans and Epicoccum spp. prevailed

in a canteen and a corridor. Both qualitative as well as

quantitative variations of microflora during the day were

observed and this is presented in Figs. 5, 6 and 7 as a

percentage contribution of particular species of fungi in

tested rooms in mornings and afternoons.

Discussion

In the face of a lack of any official reference limit

for microbiological quality in indoor air it is difficult to

fully interpret our results. However, one of the valuable

proposals of reference data were so-called Residential

Limit Values (RLV) presented by Górny and Dutkiewicz

on the WHO Expert Meeting in Berlin, 2002 [22]. The

number of bacterial flora found in university rooms in

2002 hardly fitted an upper limit of these reference values,

whereas in 2003 they sometimes exceeded this limit

(5000 cfu/m3). The fungal concentration was not higher

than proposed RLV limit (5000 cfu/m3) but it overtook in

almost all cases the level of 250 cfu/m3 – the limit proposed

by the American Industrial Hygiene Association in

2001 [26].

Looking at the variations of microorganism concentrations

in the whole investigated period it is easy to notice

a sharp increase of fungi in the air of the lecture room

and bacteria in toilets at the time of the opening of the

Fig.3. Variations in microbial concentrations in ventilated lecture

room.

Fig.4. Variations in microbial concentrations in toilets.

628 Stryjakowska-Sekulska A. et al.

Fig. 5. Mould species dominating in the ventilated lecture room in 2002 (A, B) and 2003 (A1, B1):

A, A1 - in the morning; B, B1 - in the afternoon; A, B: 1 - Cladosporium spp., 2 – Penicillium spp., 3 - Monilia spp., 4 - Mucor spp.,

5 - Acremonium spp.; A1, B1: 1 - Cladosporium spp., 2 - Aspergillus spp., 3 - Penicillium spp., 4 - Mucor spp., 5 – Alternaria spp.,

6 - another species

Fig. 6. Mould species dominating in the students canteen in 2002 (A, B) and 2003 (A1, B1):

A, A1 - in the morning; B, B1 - in the afternoon; A, B: 1 - Cladosporium spp., 2 - Penicillium spp., 3 - Mucor spp., 4 - Rhizopus spp.,

5 - Aspergillus spp., 6 - Alternaria spp. ; A1, B1: 1 - Cladosporium spp., 2 - Penicillium spp., 3 - Aspergillus spp., 4 - Rhizopus spp.

Microbiological Quality... 629

academic year. This phenomenon is undeniably connected

with an appearance of a new significant microbiological

contamination source – students attending lectures.

The human body as well as clothing is a natural place for

growing microorganisms. Strong relationship between

occupant density, human activity and microorganisms

concentration in the indoor air was reported elsewhere

[12, 31, 37]. Toivola et al. [37] found the highest bacterial

concentration in heavily populated workplaces. In schools

the highest level of bacterial contamination was detected

in the corridor and in rooms. During lessons and after lessons

the number of microorganisms was much lower [12].

In this investigation just after the short period of high

microorganisms concentration in the air of investigated

rooms a gradual decrease of microbial contamination was

observed associated with its slow drop in the outdoor air

found in parallel studies near university buildings [36].

Examination of the outdoor air also showed that microorganism

concentrations in the outdoor changed within

the whole investigated period and in 2002 a prevalence

of fungi was observed. Higher mould concentrations in

investigated rooms in 2002 compared to 2003 can be

explained by their high concentration in the outdoor air.

Only the quality of bacterial and fungal flora in the air of

toilets (Fig. 4) was much less influenced by outdoor air

contamination. Contrary to outdoor air inside investigated

toilets significantly dominating microorganisms were bacteria

amounting couple of thousands cfu/m3, whereas the

level of mould spore concentrations reached the amount

of a few hundred cfu/m3. In 2003 bacteria dominated the

outdoor air, especially at the turn of September and October.

Bacteria concentration was about 5 times higher

in 2003 than in 2002. It is probably connected with the

weather conditions prevailing at that period of time, very

conducive to infections (i.e. rapid temperature decrease at

the beginning of studies period from 22°C to about 7°C in

the middle of this period and quite high relative humidity

at 70% [36]).

It is generally accepted that a microbiological concentration

in the indoor air is similar to the outdoor values,

which means that the indoor/outdoor concentration ratio

(I/O) is close to 1. In our studies the I/O ratios for both

bacteria and fungi in most investigated rooms were lower

than this value, especially in the morning time. The situation

observed in the ventilated lecture hall (where I/O

ratios in the afternoons were lower than in the mornings)

is evidence of a proper ventilation system. Extremely high

values of I/O ratios in the afternoons for librarian lending

room and reading room, canteen, corridor and toilets can

be explained by the fact that all these places are most of

the time overcrowded with visitors. It is a main source of

microbiological contamination there. However, by com-

Fig. 7. Mould species dominating in the reading room in 2002 (A, B) and 2003 (A1, B1)

A, A1 - in the morning; B, B1 - in the afternoon; A, B: 1 - Cladosporium spp., 2 - Penicillium spp., 3 - Mucor spp., 4 - Scopulariopsis

spp., 5 - Rhizopus spp.; A1, B1: 1 - Cladosporium spp., 2 - Alternaria spp., 3 - Mucor spp., 4 - Penicillium spp., 5 – Scopulariopsis

spp.

630 Stryjakowska-Sekulska A. et al.

paring obtained average values of I/O ratios with those

proposed by Siqueira (I/O ≤ 1.5 = good; I/O = 1.5 up to

2.0 = regular; I/O > 2 = poor indoor ambient conditions)

[28, 38] indoor ambient conditions in tested rooms can be

estimated as relatively clean.

In 2002 a significant growth of so-called “outdoor

moulds” spores Cladosporium spp. was observed in afternoons,

reaching sometimes even tens of percentages. In

this year Cladosporium spp. prevailed in the outdoor air.

In the air of university canteen relatively high concentration

of spores Rhizopus spp. was found in mornings, its

contribution in the air came up to 58% in 2002 and 33%

in 2003. Rhizopus spp. is a typical “indoor mould.” However,

an unusually high concentration of this mould in the

canteen came from fruits and vegetables used for preparation

of meals. In afternoons, microbiological composition

of the air in the canteen was dominated by other typical

“indoor moulds” genera like Penicillium spp., Aspergillus

spp., Mucor spp. and “outdoor mould” Cladosporium spp.

Also a second typical “outdoor mould” Alternaria spp.

appeared in the air of investigated halls in afternoons.

These spores of both genera Cladosporium and Alternaria

emerging and raising in the course of the day in the air of

lecture halls and other rooms occupied by many people

are evidence of continuous input of microorganisms from

outside via visiting people.

In the air of the library reading room a very specific

mould genus – Scopulariopsis spp. was always found but

only in mornings. It is difficult to explain this phenomenon

but more detailed research has to be involved to clear

this problem because Scopulariopsis spp. is a major cause

of onychomycosis [39-41].

Presented results provided evidence that high concentration

of fungi in atmosphere can influence microbiological

indoor air contamination. Before the beginning of the

academic year so-called “outdoor moulds,” i.e. Cladosporium

spp., and Alternaria spp. dominated the indoor

air of investigated rooms and their concentration remains

stable. However, during the academic year a significant

variation of fungal genera in the air was observed and

concentrations of both Cladosporium spp. and Alternaria

spp as well as so-called “indoor moulds” genera like Aspergillus

spp., Penicillium spp. or Mucor spp. was growing

steadily during the daytime. Increasing concentration

of fungal spores during lectures in the course of the day,

especially those from the genera Cladosporium spp. and

Alternaria spp., can have a bad influence on health and

mood of students and teachers staying in these rooms.

According to earlier studies the microbiological quality

of indoor air is formed by two main factors: microbiological

composition of outdoor air and indoor air microbial

sources [1, 2, 10-13]. Outdoor air is very much

influenced by environment, season, the weather and even

daytime.

Data presented in this work provides evidence that

people occupying or visiting enclosed spaces play a dominating

role in the creation of indoor air microbiological

environments. The highest growth of microorganism

numbers in the course of the day was noticed in the corridor,

canteen, chemical laboratory and the library – the

most overcrowded places. It means that all rooms attended

by many visitors will be extremely exposed to risk of

high microbial contamination. Obviously, the presence of

a good ventilation system inside buildings eliminates to

some extent the influence of indoor sources.

Conclusions

1. Indoor air contamination in investigated university

rooms caused by mesophilic aerobic bacteria varied

from 120 to 2300 cfu/m3 in 2002 and from 110 to 3300

cfu/m3 in 2003. Contamination caused by fungi varied

from 130 to 1100 cfu/m3 in 2002 and from 90 to 800

cfu/m3 in 2003.

2. The microbiological quality of the air in investigated

rooms was differentiated and changed significantly

in the course of the day. In afternoons the concentration

of bacteria and much more fungi increased a few

times. The only exception was the ventilated lecture

room, where the microbiological composition of the

air was stable within the day and even presented a

tendency to fall. The increased level of fungal flora

in sufficiently ventilated rooms could be a reason for

serious health problems of people occupying those

rooms.

3. In 27% of samples the number of bacteria in indoor

air exceeded the level of bacterial contamination of

outdoor air. Almost 23% of tested indoor air samples

showed higher fungal contamination than outdoor

air. Among isolated fungi there were also strongly

allergenic and toxic species such as Cladosporium

herbarum, Alternaria alternata, Aspergillus flavus,

Aspergillus versicolor, Aspergillus niger, and Penicillium

expansum.

References

1. ABDEL HAMEED A.A., FARAG S.A. An indoor bio-contaminants

air quality. International Journal of Environmental

Health Research 9, 313, 1999

2. DH ARMAGE S., BAILEY M., RAVEN J., MITAKAKIS

T., THIEN F., FORBES A., GUE ST D., ABRAMSON M.,

WALTERS E.H. Prevalence and residential determinants of

fungi within homes in Melbourne, Australia. Clinical and

Experimental Allergy 29, 1481, 1999

3. PIOTROWSKA M., ŻAKO WSKA Z., GLIŚCIŃSKA A.,

BOGUSŁAWSKA-KOZŁO WSKA J. The role of outdoor

air on fungal aerosols formation in indoor environment.

Proceedings of the II International Scientific Conference:

Microbial Biodegradation and Biodeterioration of Technical

Materials, 113-118, Łódź, Poland, 2001, [In Polish]

4. FLANNIGAN B. Microbial Aerosols in Buildings: Origins,

Health Implications and Controls. Proceedings of the II International

Scientific Conference: Microbial Biodegradation

Microbiological Quality... 631

and Biodeterioration of Technical Materials, 11-27, Łódź,

Poland, 2001

5. L A-SERNA I., DO PAZO A., AIRA M.J. Airborne fungal

spores in the Campus of Anchieta (La Laguna, Tenerife/Canary

Is.). Grana 41, 119, 2002

6. SARICA S., ASAN A., OTKU N M.T., TURE M. Monitoring

Indoor Airborne Fungi and Bacteria in the Different Areas

of Trakya University Hospital, Edirne, Turkey. Indoor

and Built Environ. 11, 285, 2002

7. PETERMAN T.K., JALO NGO M.R., LIN Q. The Effects of

Molds and Fungi on Young Children’s Health: Families’ and

Educators’ Roles in Maintaining Indoor Air Quality. Early

Childhood Education Journal 30(1), 21, 2002

8. Y AZICIOGLU M., ASAN A., ONES U., VATANSEVER

U., SEN B., TURE M., BOSTANCIOGLU M., PALA O.

Indoor Air Fungal Spores and Home Characteristics in Asthmatic

Children From Edirne Region of Turkey. Journal of

Allergy and Clinical Immunology, January, 2002

9. ROJAS T.I., MARTINEZ E., GOMEZ Y., ALVARADO Y.

Airborne spores of Aspergillus species in cultural institutions

at Havana University. Grana 41, 190, 2002

10. GUTAROWSKA B., JAKU BOWSKA A. The estimation

of moulds air pollution in university settings. In: Problems

of indoor air quality in Poland’2001, 103-112, ed. T.

Jędrzejewska-Ścibak, J. Sowa, Publishing House of Warsaw

University of Technology. Warsaw 2002, [In Polish]

11. D AISEY J.M., ANGEL W.J., APTE M.G. Indoor air quality,

ventilation and health symptoms in schools: an analysis

of existing information. Indoor Air 13, 53, 2003

12. K ARWOWSKA E. Microbiological Air Contamination in

Some Educational Settings. Polish J. Environ. Studies 12(2),

181, 2003

13. WÓJCIK-STOPCZYŃ SKA B., FLAKO WSKI J.,

JAKU BOWSKA B. Mikroflora of university canteen air.

PZH Annals 54 (3), 321, 2003, [In Polish]

14. FILIPIAK M., PIOTRASZE WSKA-PAJĄK A., STRYJAKO

WSKA-SEKUL SKA M., STACH A., SILNY W. Outdoor

and indoor air microflora of academic buildings in

Poznań. Progress in Dermatology and Allergology 21(3),

121, 2004

15. PIECKO VA E., KU NOVA Z. Indoor fungi and their ciliostatic

metabolites. Ann Agric Environ Med. 9, 59, 2002

16. FLANNINGAN B. Mycotoxins in the air. International Biodeterioration

23(2), 73, 1987

17. FLANINGAN B. Alergenic and toxigenic microorganisms

in houses. Journal of Applied Bacteriology Symposium Suplement

70, 61, 1991

18. L IPIEC A. Moulds – important environmental antigen.

Therapy 3, 27, 1997, [In Polish]

19. ZY SKA B. Biological hazards inside a building, ed. Publishing

house “Arkady”, Warsaw, 1999 [In Polish]

20. MORITZ M., PETERS H., NIPKO B., RUDE N H. Capability

of air filters to retain airborne bacteria and molds in

heating, ventilating and air-conditioning (HVAC) systems.

International Journal of Hygiene and Environmental Health

203, 401, 2001

21. THE CALIFORNIA DE PARTMENT OF HE ALTH SERVICES

ENVIRONMENTAL HE ALTH INVESTIGATIONS

BRANCH: Mold in my school: what do I do?, July,

2001

22. GÓRNY R.L., DU TKIEWICZ J. Bacterial and fungal aerosols

in indoor environment in Central and Eastern European

Countries. Ann Agric Environ Med 9, 17, 2002

23. O BBARD J.P., FANG L.S. Airborne Concentrations of Bacteria

in a Hospital Environment in Singapore. Water, Air and

Soil Pollution 144 (1), 333, 2003

24. GÓRNY R.L. Harmful biological factors: standards, recommendations

and proposals for admissible values. Basis

and Methods of Estimation of Work Environment 3(41), 17,

2004, [In Polish]

25. ABEL E., ANDE RSSON J.V., DAWIDO WICZ N., CHRISTOPHE

RSEN E., HANSSEN S.O., LINDÈN A-L., LINDVALL

T., PASANEN A-L. The Swedish key action “the

healthy building” – research results achieved during the

first three years period 1998-2000. In: Levin H, ed. Indoor

Air 2002. Proceedings: 9th International Conference on Indoor

Air Quality and Climate, Monterey, California, June

30 – July 5, 2002, . Santa Cruz, California p. 996-1001,

2002

26. www.wondermakers.com, Information Series Post-Remediation

Guidelines. Wonder Makers Environmental, Inc.,

December, 147, 2001

27. BERK J.B. et al. Field monitoring of indoor air quality. In:

1979 Annual report of the energy and environment division,

Berkeley, Lawrence Berkeley Laboratory, University of

California, 1980

28. DE AQUINO NETO F.R., DE GÓES SIQUE IRA L.F.

Guidelines for indoor air quality in offices in Brazil. Proceedings

of Healthy Buildings 4, 549, 2000

29. www.iaq.gov.hk/tables.html, IAQ Objectives for offices &

public places in Hong-Kong

30. POL ISH STANDARD PN 89/Z-04008/08

31. FLE ISCHE R M., BOBER-GHEK B., BORTKIEWICZ

O., RUSIECKA-ZIOLKO WSKA J. Microbiological control

of airborne contamination in hospitals. Indoor and Built Environment

15(1), 53, 2006

32. K RUCZALAK K., OL ANCZUK -NEY MAN K. Microorganisms

In the Air Over Wastewater Treatment Plants. Polish

Journal of Environmental Studies 13(5), 537, 2004

33. SIMSEKL I Y., GÜCIN F., ASAN A. Isolation and identification

of indoor airborne fungal contaminants of food production

facilities and warehouses in Bursa, Turkey. Aerobiologia

15, 225, 1999

34. HOL T. J.G., KRIEG N.R., SNETH P.H.A. STANLEY J.T.,

WILL IAMS S.T. Bergey’s Manual of Determinative Bacteriology,

9th ed., Williams and Wilkins, Baltimore, Maryland,

USA, 1994

35. FASSATIOVA O. Microscopic fungi in technical microbiology.

WNT, Warsaw 1983, [In Polish]

36. BUGAJNY A., KNOPKIEWICZ M., PIOTRASZE WSKAPAJĄK

A., STRYJAKO WSKA-SEKUL SKA M., STACH

A., FILIPIAK M. On the microbiological quality of the outdoor

air in Poznań/Poland. Polish Journal of Environmental

Studies 14(3), 287, 2005

37. TOIVOL A M., ALM S., REPONEN T., KOL ARI S., NEVALAINEN

A. Personal exposures and microenvironmental

632 Stryjakowska-Sekulska A. et al.

concentrations of particles and bioaerosols. Journal of Environment

Monitoring 4, 166, 2002

38. BRICKU S L.S.R., SIQUE IRA L.F.G., DE AQUINO NETO

F.R., CARDO SO J.N. Occurrence of Airborne Bacteria and

Fungi in Bayside Offices in Rio de Janeiro, Brazil. Indoor

Built Environment, 7, 270, 1998

39. HU NTER A., GRANT C., FLANNIGAN B., BRAVERY

A.F. Mould in buildings: the air spora of domestic dwellings.

International Biodeterioration 24(2), 81, 1988

40. GNIADEK A., MACURA A.B. Mycological flora in the environment

of social welfare homes and its influence upon

the skin their inhabitants. Annales Universitatis Mariae Curie-

Skłodowska Lublin – Poland, Sectio D 58(Suppl. 13),

411, 2003

41. MILLE R J.D., LAFLAMME A.M., SOBOL Y., LAFONTAINE

P., GREE NHALGH R. Fungi and fungal products

in some Canadian houses. International Biodeterioration

24(2), 103, 1988