There is potential for severe haze episodes to occur in Singapore, and the main air
pollutant in the event of haze is particulate matter (PM). Short-term exposure
(continuous exposure to unhealthy daily average PSI levels over a period of a few days)
to haze like the pattern seen in Singapore may cause irritation of the eyes, nose, and
throat in healthy individuals. Haze particles can also affect the heart and lungs,
especially in people who already have chronic heart or lung disease e.g., asthma, chronic
obstructive pulmonary disease (COPD), or heart failure.

Haze is a perennial problem in Singapore. Commercially available disposable particulate
respirators are typically certified for surgical and occupational use. The test standards
are specified according to adult breathing conditions and fit. As commercially available
disposable masks designed for occupational use are mainly for adults, such masks do not
fit well on children, they do not serve well as protection against Particulate Matter 2.5
(PM 2.5), an air pollutant found in transboundary smoke haze.

Commercially available disposable particulate respirators are typically certified under
the NIOSH and CE EN 149:2001+A1:2009 standards for surgical and occupational use. These
respiratory masks are tested to filter particulate matter in the air with varying degrees
of filtering efficiencies according to the respective categories, e.g. NIOSH KN95
certifies respirators to filter at least 95% of non-oil particulates. The test standards
are specified according to adult breathing conditions and fit.

Children's respiratory minute volume and rate are different from adults. As commercially
available disposable masks designed for occupational use are mainly for adults, such
masks do not fit well on children, they do not serve well as protection against
Particulate Matter 2.5 (PM 2.5). As haze is a perennial problem, and there is potential
for severe haze episodes to occur again, there is a need to consider the development of
disposable particulate respirator with enhanced safety and comfort specific for use in
children.

ST Engineering Innosparks Pte. Ltd. developed a new type of disposable particulate
respirator (hereon referred to as AIR+ KN95 Mask) that is suitable for use in both adults
and children, from ages 7 and above. The masks come in S, M and L sizes, and have been
tested according to the KN95 protocol for respirators.

Studies have shown that prolonged wearing of disposable particulate respirators may lead
to an increase in carbon dioxide (CO2) levels in the dead space of the respirator as well
as in the re-breathing of the expired air when wearing it. The increased CO2 levels may
result in headaches, increased irritability, and breathing difficulty. In addition, there
is some discomfort due to the accumulation of heat and humid air in the dead space of
between the respirator and face. However, the mask design is based on our previous AIR+
Smart Mask specifications, which was previously evaluated in a clinical trial performed
in collaboration with NUH and the data published in a peer-reviewed journal1, showing no
significant increase in CO2 retention and the mask was found to be comfortable at rest
and on mild exertion. The mask was commercially launched in 2015.

As the masks were developed specifically for school-going children, this study is
designed to explore whether the new disposable particulate respirator is safe and
effective for use in healthy children aged 7 to 14 years of age. This is through
measuring the variation of carbon dioxide levels in children whilst wearing the AIR+ KN95
Mask. End-tidal carbon dioxide pressure (ETCO2) is a good indicator of arterial carbon
dioxide pressure (PaCO2) in healthy adults and children and has been used for continuous
direct assessment of PaCO2 in clinical contexts. The normal range of PaCO2 is from 35 -
45 mmHg. As there is a slight margin of difference between ETCO2 and PaCO2 values during
measurement of about 1.6 +/- 4.3mmHg, this study defines 30 to 50mmHg as the acceptable
range for ETCO2 levels.