Introduction: Most health advisories related to outdoor physical activity during haze are general in nature. The advisories normally advise everyone to reduce or limit prolonged exertion or heavy exertion without mentioning the acceptable duration for performing outdoor physical activity causing difficulty for public to decide to stop or cancel a particular outdoor or sport event. The aim of this paper is to determine the acceptable duration for performing outdoor physical activity pattern during haze based on API level.
Methods: Health risk assessment approach that comprises of hazard identification, exposure assessment, dose-response, and risk characterization steps was used to determine the potential inhaled dose and risk associated with performing the physical activity during haze. We have considered many factors that include time spent for physical activity patterns for Malaysian adult, age and physical intensity-specific inhalation rate (m3/min), and the indoor/outdoor ratio of PM10. A hypothetical exposure scenario of PM10 was created using the breakpoints of PM10 concentration for the calculation of respective API levels during haze.
Results: The association between physical activity pattern, API level and risk quotient were presented in the form of risk radar diagram. Based on the 50th percentile inhalation rate, all prolonged exertion and heavy exertion should be avoided when API reach >201 (very unhealthy) and >175 (unhealthy) respectively. Below the said API, the duration for performing prolonged exertion and heavy exertion should be reduced according to the API level. When API reaches 140, high intensity physical activity should be limited to < 90 minutes. A football match which requires 90 minutes, should be postponed of cancelled if API > 140. Whereas, for the same API level, prolonged exertion (moderate intensity physical activity) should be limited to 4 hours.
Conclusions: Reducing the physical activity is an effective strategy to lower the dose of inhaled pollutants and reduce the health risk during poor air quality. Based on the assessment, taking into account the uncertainty of risk assessment methodology, we proposed all prolonged exertion should be avoided when API reach very unhealthy status (>201). Below the said API level, outdoor physical activity should be reduced according to the level of API respectively. The recommendation is not applicable for the sensitive groups. The computed risk radar provide a valuable guide for the public to organize or considering postponing an outdoor event during haze.
Introduction During haze, at what level should Air Pollutant Index (API) showed, public
or private school be closed is not without controversy and is very much
debated. Therefore, the aim of this paper is to objectively quantify the
potential inhaled dose of PM10 associated with exposure at school and home
microenvironments during haze. The result of the health risk assessment will
be used to propose the API level for closing the school during haze episode.
Methods A hypothetical haze exposure scenario was created using the breakpoints of
PM10 concentration for calculation of API and respective inhaled dose during
haze. To determine the potential inhaled dose, we have considered many
factors that include time spent for specific physical intensity at school and
home microenvironments, age-specific and physical intensity-specific
inhalation rate (m3/min), and the indoor/outdoor ratio of PM10. To calculate
risk quotient (RQ), the inhaled dose was compared with the health reference
dose computed based on the concentration of PM10 in the Malaysian
Ambient Air Quality Standard.
Results When considering the specific exposure at each microenvironment (school
and home), the potential inhaled dose of PM10 was substantially lower when
school is closed for both primary and secondary school. The calculated risk
quotient (RQ) indicates that primary school children are likely to be affected
at slightly lower PM10 concentration (equivalent to API of 197) as compared
to secondary school children. Short duration of high physical activity
intensity during school breaks has contributed to a large proportion of inhaled
dose among school children indicating the important to avoid physical
activities during haze.
Conclusion Based on the assessment, taking into account the uncertainty of risk
assessment methodology, we proposed school to be closed when API reach
190 for both primary and secondary schools. These findings and
recommendations are only valid for naturally ventilated school and applicable
in the context of the current API calculation system and the existing
Recommended Air Quality Guideline values in Malaysia.