Concerned parents are calling on the New South Wales Department of Education to do more to ensure schools are prepared to protect children from smoke and airborne pollution.

On Tuesday, parts of Sydney recorded air pollution 11 times higher than the level deemed hazardous, with health authorities recommending that people stay indoors and use air conditioning to help filter out pollution.

While some NSW schools have cancelled sports and outdoor playtime in response to the smoky conditions, parents are calling on the government to issue clearer guidelines to ensure children are not exposed to adverse health effects.

In a letter to state Education Minister Sarah Mitchell, Australian Parents for Climate Action organiser David McEwen asked what advice and training in dealing with hazardous air quality had been provided to teachers and principals, and what elevated precautions were being implemented for children with known respiratory conditions.

The NSW Department of Education provided The Feed with a one-page factsheet on "air quality considerations for schools during bushfires", which was sent to public school principals last month and reissued last week.

The fact sheet encourages schools to "look for ways to minimise exposure and adverse effects of bushfire smoke", such as staying indoors with air-conditioning turned on to filter air if possible.

Schools are also advised to "consider cancelling sporting events and unnecessary outdoor activities", and to closely monitor students with asthma or other diagnosed health conditions.

The factsheet does not mention the Air Quality Index, which is updated hourly to reflect current air pollution levels as well as advice on whether to avoid outdoor activity.

Tori Quine, a parent of six-year-old twins, told The Feed she was concerned that schools have not been given clear instructions about how to operate on days with hazardous air quality. She and a group of parents plan to protest outside Marrickville West Primary School on Thursday morning to draw attention to the issue.

"Why isn't there a blanket statement across NSW schools saying okay, it's a hazardous level, we're going to have to be indoors today? Nothing like that is happening," she said.

We want to have really clear-cut action, so ideally every principal every morning during this period is sent the pollution level, therefore please do x, y, z.

"We'd like to have a bit more authority about it, really taking it seriously. Because this is new territory for us as Australians -- we used to have a day or two like this here or there. But not back to back, not day to day."

'An overlooked health emergency'

Associate Professor Camille Raynes-Greenow works at the University of Sydney School of Public Health. She told The Feed that the problem of air pollution must be taken more seriously.

"Exposure to air pollution is an overlooked health emergency for children around the world. Breathing clean air is essential for children's healthy development," she said.

"School age children with pre-existing respiratory conditions such as asthma (which is prevalent in Australia) are also especially vulnerable."

In the short term, Raynes-Greenow said that key steps schools can take include restricting outdoor activities, using an air conditioner if available, and being mindful that younger children are more at risk.

In the long term, however, Raynes-Greenow said governments must prioritise the "main problem": reducing sources of air pollution.

We need leadership and planning at a national level to deal with this emergency.

Bigger focus needed on prevention, expert says.

Professor Lidia Morawska, Director of the International Laboratory for Air Quality and Health, agreed, and said that the government's response to the problem had so far been lacking.

"I don't think there's been anything done about this or to inform the public, or say what to do in these situations."

"In terms of what to do, the best thing -- which is obviously not a short-term solution -- is to prevent things like this."

"In China for example there's a lot of work done in preventing severe air pollution. In Australia we are talking about a different situation because this isn't an air pollution so much caused by sources operated by humans, but rather bushfires."

"Bushfires, however, are related to climate change which is affected by what people are doing. A longer term strategy is not to build more facilities to protect ourselves inside, but to reduce emissions as quickly as possible, to prevent this situation full stop."

Australian Parents 4 Climate Action have joined 228 parents' groups from 28 countries in signing an open letter calling on negotiators at COP25 to take urgent action against climate change.

The open letter was delivered to Australia's COP25 delegate Angus Taylor's office this week.