Air pollution in Christchurch “alarming”

Press, Volume CXV, Issue 33874, 20 June 1975, Page 1

Air pollution in Christchurch “alarming”

A warning that Christchurch can expect more deaths and hospital admissions as a result of the degree of air pollution which has occurred in the city recently was made hy a doctor yesterday.

Dr J. A. McLeod, a physician in the respiratory unit at the Princess Margaret Hospital, said after hearing about the maximum smoke-level readings for several days: “These figures are certainly alarming.”

A meeting of the Canterbury Regional Planning Authority’s airpollution committee was informed that the average smoke concentration in the central city for the 24 hours to 9 a.m. yesterday was 397 microgrammes of smoke per cubic metre of air.

In the inner suburbs for the same period the figure was 506, and in the outer suburbs, 270. For a two-hour period on Wednesday evening, smoke reached a maximum concentration of 1102 in the inner city and 3076 in the Lin-wood-Avonside area.

Dr McLeod said that by using World Health Organisation figures and taking into account sulphur dioxide levels, it could be expected that there would be an increased number of deaths and more hospital admissions when the level exceeded 500 for a 24-hour period.

When the level was more than 250, a deterioration in people with lung and heart diseases could be expected.

‘Stay indoors’

There was bound to be some obstruction of bronchial tubes when the level exceeded 1500, said Dr McLeod. “Even healthy joggers who were out in Avonside last evening could expect to experience some degree of obstruction to their breathing,” he said. On treatment or prevention, Dr McLeod said: “All we can say medically is. that patients in these smoky areas should stay indoors, and, if possible, breathe through their noses. The nose has a good filtering system.”

The chief chemicals inspector of the Department of Health (Mr D. R. Pullen) said that the 24-hour smoke readings for Wednesday evening were above the World Health Organisation regulations at all the 13 monitoring stations except Islington.

The two-hour readings reached a peak of 397 in the inner city between 6 p.m. and 10 p.m., and at the Lin-wood-Avonside station the level started to build up at 4 p.m. and reached the peak of 3076 between 10 p.m. and midnight. This was unusual, as the peak was normally two hours earlier. North-west airflow Mr Pullen said that for a two-hour period anything over 500 was considered to be high. For 24-hour averages, 120 and over was high. The reason for Wednesday evening’s particularly high smoke concentration was a north-west airflow above Christchurch, with an intense temperature inversion over the city, he said. Mr P. V. Neary, of the Clean Air Society, said he suspected that domestic smoke was worse medically than industrial smoke, be-

cause of the smaller particles. Dr McLeod agreed that this was correct. i Dr N. J. Peet, a senior lecturer in chemical engineering at the University of Canterbury, said that tests by the Clean Air Council showed that an open fire, even when carefully stoked, was capable of putting out 5 per cent of the weight of coal burnt in the form of smoke. When collected, this smoke did not look like black soot but a “mass of almost glistening tar.” Fairly simple arithmetic showed that if three-quarters of Christchurch households had coal fires on a cold evening, then 20 to 30 tons

of smoke could be emitted during the course of one evening. Dr Peet said he was concerned about the number of people who considered the “so-called energy crisis” the reason for using coal instead of electricity. The useful energy equivalent of all the coal burnt domestically was equal to about a quarter of 1 per cent of New Zealand’s total annual electricity generation. The Cook Strait power cable was running to capacity and the South Island lakes were full, and so further savings of electricity in the South Island would not bring increased benefits in oil savings.

The chief City Health Inspector (Mr A. P. Millthorpe) said that the high smoke concentrations had occurred on a number of days recently. "These figures and opinions that we now have should prove to the public and the authorities that there is an air-pollution problem here which has to be dealt with, and that there are some residents who are going to suffer meantime,” he said.

The chairman of the meeting (Mr D. F. Caygill) said that when a list of approved appliances mentioned by Mr Millthorpe was released, in perhaps two weeks or so, all that was lacking for the implementation of clean-air zones was information about what the Government intended doing by way of financial subsidy for those who had to convert open fires.