On the streets of Pakistan’s second biggest city, smog stings eyes and burns throats. Inside homes, few people can afford air purifiers to limit the damage of toxic particles that seep through doors and windows.

Lahore, a city of 14 million people stuffed with factories, regularly ranks among the world’s most polluted cities, but it has hit record levels this month.

Schools have closed in the main cities of Punjab province, of which Lahore is the capital, until November 17 in a bid to lower children’s exposure to pollution, especially during the morning commute when it is often at its highest. "The children are constantly coughing, they have constant allergies. In schools we saw that most of the children were falling sick,” said Rafia Iqbal, a 38-year-old primary school teacher in the city that borders India.

According to the international Air Quality Index (AQI) scale, an index value of 300 or higher is "hazardous” to health and Pakistan has regularly tipped over 1,000 on the scale.The World Health Organization (WHO) says air pollution can trigger strokes, heart disease, lung cancer and other respiratory diseases. It is particularly punishing for children, babies, and the elderly.