Study finds ‘heat wave’ like conditions in cars

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Risks for passengers include stress, strokes and fluctuation in blood pressure

  • The ambient temperature inside cars could shoot up to as much as 65°C and induce conditions akin to a heat stroke, says a study that measured temperature and relative humidity levels.
  • The objective of the study, led by researchers at the Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, was to assess “thermal comfort” (the degree of warmth that people deem as comfortable) in cars.
  • Along with the temperature and humidity, the study also evaluated people’s experience of thermal comfort in sedans, sports utility vehicles and hatchbacks, in Chandigarh.
  • The predicted mean vote (PMV) was observed to be the worst for sedans, the percentage of persons dissatisfied (PPD) was observed to be 100% in all cases, showing dissatisfaction for all car models. 
  • The concentration of carbon dioxide and carbon monoxide ranged between 113-1,127 parts per million and 0–3.9 ppm, respectively, for the front of the car.
  • The PMV and the PPD are metrics to measure thermal comfort.
  • The measurements showed that the front of the car showed a higher maximum temperature than the back, while relative humidity was observed to be lower in the front than the back for all models. 
  • The temperature recorded in a sedan was higher than in a SUV and in a hatchback. 
  • The higher temperature was due to ambient conditions on different days and also due to the colour of the car.
  • The higher temperature in a sedan may also be due to its black colour, which is a good absorber of heat while the SUV and hatchback were white, which has higher reflectance.
  • The conditions akin to a heatwave could manifest and — given changes in climate and higher average temperatures — would lead to several more ailments such as heat stress, heat strokes and fluctuation in blood pressure.
  • Understanding heat waves in micro-environments is also important given warming trends. Last year was the seventh warmest since record-keeping commenced in 1901. 
  • The annual mean surface air temperature, averaged over the country, was 0.36°C above average. 
  • The average is defined as the mean temperature from 1980-2010.
  • The highest warming observed over India was during 2016 or 0.71°C above the mean.
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