KARACHI: Some 20 per cent kitchens studied in district Central were found to have higher concentrations of carbon monoxide (CO), an odourless and colourless gas that can kill, says a study recently published in Pakistan Journal of Science.

The study “Carbon monoxide concentrations in kitchens of gas-fired burners, Karachi, Pakistan” was conducted by Prof Zafar Iqbal Shams and his team at the Institute of Environmental Studies, Karachi University (KU).

The study investigated the carbon monoxide concentrations in kitchens of middle-income inhabitants residing in 54 bungalows and 25 apartments in district Central

“While the study does highlight an issue of public health importance, the results may not be reflective of what’s happening at a larger scale in society,” explained Prof Shams, adding that the team could not widen its scope to lower income areas due to funds’ shortage.

28,000 deaths, 40m respiratory disease cases are reported annually due to indoor air pollutants in country

People living in small congested places, he said, were likely to be more at a risk of hazardous indoor pollution.

“Undetected or unsuspected carbon monoxide exposure can result in accidental deaths. It’s one of the leading causes of poisoning morbidity and mortality in the western world,” he said.

Citing the Murree tragedy that took scores of lives early this year, Prof Shams said people died of carbon monoxide poisoning when they stayed in cars with turned on heaters and fell asleep. “In the USA, more than half of accidental carbon monoxide poisoning deaths are caused by motor vehicle exhaust followed by domestic gas appliances.”

Study’s findings

The investigation showed that over 80 per cent of kitchens of the bungalows and apartments met the World Health Organisation (WHO) guidelines on carbon monoxide for maximum-time weighted permissible limit for one, eight and 24 hours’ of human exposure.

“However, carbon monoxide concentrations in some kitchens were substantially higher in both the housing categories for all the time-weighted categories.

“The higher carbon monoxide levels in some kitchens may be because of their inadequate ventilation or outdoor contaminated air,” the study says.

It also points out that the kitchens of the apartments demonstrated the highest eight-hour carbon monoxide concentration during evening hours, which may be due to greater fossil-fuel related business activities within and around the apartments such as roadside catering and higher vehicular traffic emissions.

“Appropriate ventilation of kitchens may reduce their CO concentrations to meet the guidelines for getting out of any health-related risk. The outdoor CO concentrations can be reduced by decreasing the vehicular traffic jam and catering activities around the apartments,” the study suggests.

It cites the World Bank 2006 report according to which 28,000 deaths and 40 million cases of respiratory diseases are reported annually due to indoor air pollutants in Pakistan.

It refers to a 2008 study on indoor carbon monoxide and PM 2.5 (particulate matter of 2.5 micrometres or smaller) concentrations conducted in Rehri Goth, which demonstrated that women involved in cooking with biomass were potentially vulnerable to exposure to high concentrations of CO and PM2.5.

Carbon monoxide is found in fumes produced any time when people burn fuel in cars or trucks, small engines, stoves, lanterns, grills, fireplaces, gas ranges, or furnaces. It can build up indoors and poison people and animals who breathe it.

According to experts, elevated ambient air concentrations of CO are hazardous because inhaled CO enters the bloodstream and reduces the amount of oxygen that the blood can deliver to the body’s organs (like the heart and brain) and tissues. At extremely high levels, the CO can cause death.

The most common symptoms of CO poisoning are headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion.

People who are sleeping or drunk can die from CO poisoning before they have symptoms.

Published in Dawn, April 20th, 2022